You can connect to the internal software of the DM24 over its output serial port and communicate with it.
To enter command mode from Scream!, right-click on the digitizer's icon and select Terminal... from the menu that pops up. A window will open, and once the digitizer and computer are communicating properly you will see the prompt
ok
If you prefer, you can use a terminal program on your computer (such as minicom on Linux, or hypertrm on Microsoft Windows) to connect to the DM24.
Whilst you are in terminal mode, data transfer will be interrupted; the digitizer may use any Flash memory as a temporary store, depending on how you have configured it. Some commands, such as SET-TAPS, require a reboot to take effect.
Güralp DCM and AM modules also allow you to send commands direct to the digitizer using the command-line tool gcli. For more information, please see the manual for your data module.
If you have problems connecting to the digitizer's console, you should check that the serial port's options and baud rate are set correctly in Scream! or your terminal program. As supplied, the DM24 expects connections at 19200 baud, with 8 data bits, no parity bit and 1 stop bit. No flow control is used.
The DM24 uses FORTH to implement its features. To issue a command in FORTH, you must supply the arguments before the command, for example:
3 SENSOR-TYPE
In FORTH, anything you enter is termed a word. New words (case insensitive) are placed on a stack. Some words are known to the system, and may represent commands; if a command finds itself at the top of the stack (e.g. because it is the last thing you typed), they will execute, remove themselves from the stack, and then remove further items from the stack to use as arguments. Thus, in the command
3 SENSOR-TYPE
the 3 has no immediate effect, so stays on the stack; SENSOR-TYPE takes itself and the previous item (here 3) off the stack, then performs its action on the 3 (here, setting the configured sensor type to 3, representing a CMG-3T sensor.)
If a command completes with nothing remaining on the stack, the digitizer will show the prompt ok. Otherwise, the prompt will remind you that the digitizer is waiting for you to complete the command. Some commands, such as SAMPLES/SEC, clear the stack automatically after they execute.
Some commands are interactive, and will ask you to provide extra information after you execute them. In the following sections, interactive commands are shown as example sessions, where information you enter is given in medium and messages returning from the DM24 are given in bold.
The DM24 has an on-board help system which can be accessed with the commands HELP and EXPLAIN.
HELP
Syntax: HELP
Lists all the commands which are recognized by the digitizer.
If the command you want is not listed:
The command may be in the extended dictionary. This dictionary contains certain advanced commands, as well as exposing internal digitizer functions and variables. To enable the extended dictionary, issue the command ok-1.
When you have finished using the extended dictionary, close it with the command [seal], so you do not inadvertently change the internal settings with subsequent commands.
Alternatively, the command may not be implemented in the firmware version you have installed. Check the Güralp Systems web site for updated firmware.
EXPLAIN
Syntax: EXPLAIN command
Displays a short message describing the syntax of command and its effect.
Syntax: SET-ID (interactive)
Sets the system identifier and serial number of the DM24 to values you supply.
SET-ID
System Identifier ? (e.g. ALPHA,) DM24, Serial # ? (e.g. 1234,00) 4507,00
The system identifier you supply may contain up to 5 alphanumeric (0-9A-Z) characters, and must have a comma after it.
The serial number you supply must contain exactly 6 alphanumeric (0-9A-Z) characters, and must include a comma after the fourth character.
Syntax: type SENSOR-TYPE
Tells the DM24 which kind of sensor is attached to it. This affects whether or not the digitizer exposes commands such as locking and centring.
type can be one of
1, for CMG-40T sensors,
2, for CMG-3ESP sensors,
3, for CMG-3T analogue sensors, or
4, for CMG-3TD sensors.
Syntax: type GPS-TYPE
Tells the DM24 which kind of GPS is attached to it.
type can be one of
0, if no GPS is available, or
2, for attached GPS equipment using the NMEA protocol.
HR-CYCLE
Syntax: interval HR-CYCLE
Sets the time to wait between GPS synchronizations.
To save power, the DM24 can switch off the attached GPS receiver once its internal precision clock has been successfully synchronized. The GPS receiver is reactivated every interval hours to ensure that the clock remains correct, and shut down again once the clock error has stabilized.
Setting interval to zero disables this function, i.e. the GPS will be powered all the time. This is the best setting to use in installations with access to mains (outlet) power. The maximum allowed value for interval is 23.
SET-CLOCK
Syntax: SET-CLOCK (interactive)
Sets the internal clock.
SET-CLOCK
Enter Date & Time -
YYYY MM DD HH MM SS
2006 02 01 12 53 25 Clock set to 2006 2 1 12:53:27 ok_SBHY
The time should be entered in the form year month day hour minute second, padding each field with zeroes so that they line up with the guide above.
If the DM24 does not recognize the time format you have used, it will output the message Invalid Time Entry.
This setting will be overridden when the GPS system next synchronizes the clock.
TIME?
Syntax: TIME?
Displays the current date and time.
LEAPSECOND
Syntax: yyyy mm dd LEAPSECOND
Manually notify the digitizer of an upcoming leap second. This command is not normally necessary, since GPS already has support for leap seconds. However, some units do not properly interpret the GPS signals. See SQPATCH, below.
The leap second is taken to be at the end of the day yyyy-mm-dd.
SQPATCH
Syntax: SQPATCH ENABLE or SQPATCH DISABLE
Enables or disables the internal patch for older GPS receivers based on Trimble Lassen SQ units. These units misinterpret the GPS system's advance notification of a leap second, and consequently run one second slow until the leap second occurs.
With SQPATCH enabled, the time reported by the digitizer is offset by 1 second to counteract this problem. If you have set LEAPSECOND, above, SQPATCH will automatically be disabled when the leap second occurs, and the digitizer will then run normally.
GPS receivers with the latest firmware do not suffer from this problem.
To find out whether SQPATCH is currently enabled, issue the command
.SQPATCH
Syntax: instrument angle AZIMUTH
Some borehole digitizers can rotate incoming signals algorithmically as they are digitized. This feature allows you to compensate for an instrument being out of alignment with the North/South axis. To use it, first measure the orientation of the sensor, then connect to the digitizer and issue an AZIMUTH command, giving the angle you have measured.
instrument tells the digitizer which instrument to apply the rotation to; 0 for a 4-channel digitizer.
angle is the measured angle of deviation from the North/South axis, in tenths of a degree. The angle of deviation is the negative of the angle by which you want incoming signals to be rotated. Like all other parameters, it must be an integer (i.e. a whole number of tenths of a degree.)
You can measure the orientation of a borehole sensor by placing a reference sensor nearby and carrying out coherence calculations. An extension to Scream! is available which can do this for you. For details, see the manual for your sensor or for Scream!.
The AZIMUTH command only alters the digitizer's CMOS settings. You will need to re-boot the digitizer to transfer them to the DSP.
Syntax: channel CROSS
Alters the DSP's transformation matrix to invert one of the digitizer channels. channel is one of 0 (vertical), 1 (N/S), 2 (E/W) and 3 (auxiliary).
The CROSS command only alters the digitizer's CMOS settings. You will need to re-boot the digitizer to transfer them to the DSP.
If you need to set both AZIMUTH and CROSS, you must issue AZIMUTH first, since it overwrites the matrix.
Syntax: port baud-rate BAUD
Sets the baud rate for one of the serial ports on the DM24, in bytes per second. port can be
0, for the DATA OUT port,
1, for the GPS port, or
2, for the DATA IN port.
For example,
0 38400 BAUD
1 4800 BAUD
2 38400 BAUD
This will reset a standard single-sensor DM24 to its default configuration.
The allowable values for baud-rate are 4800, 7200, 9600, 14400, 19200, 38400, 57600, 115200 and 230400. For compatibility reasons, 1152 is also accepted, setting the baud rate to 115200.
GPS inputs should always be set to 4800 baud.
STOPBITS
Syntax: port number-bits STOPBITS
Sets the number of stop bits used for one of the serial ports on the DM24. port can be
0, for the DATA OUT port,
1, for the GPS port, or
2, for the DATA IN port.
By default, the DM24 uses 1 stop bit on all ports.
Syntax: +MODEM (interactive)
Instructs the DM24 to use a modem connected to the DATA OUT port to contact a remote device and transmit data stored in the Flash memory.
The DM24 will dial out every time it generates a heartbeat message, and also whenever a trigger occurs. You can change the interval between heartbeat messages with the HEARTBEAT command, below.
When you issue +MODEM for the first time, the digitizer will prompt you to enter a telephone number:
+MODEM
Phone# is not set Enter phone# 00441189819056
Phone# 00441189819056 Flash FIFO : Circular Configuration for dial out ok_DEMO00
If you have already configured a telephone number, the command will print out the current setting and ask if you want to change it.
+MODEM
Phone# 00441189819056 New number? y/n y
Enter phone# 00441189819943
Phone# 00441189819943 Flash FIFO : Circular Configuration for dial out ok_DEMO00
+MODEM also changes the filing mode of the digitizer to FILING, so that all incoming data is stored in Flash memory ready to be downloaded. When the dial-out takes place, all new data in Flash memory is transmitted. By configuring the DM24 to transmit only triggered streams, you can create a system which “wakes up” on a trigger, connects to a data centre using the modem, and delivers the triggered data in close to real time.
Syntax: -MODEM
Disables automatic modem dial-out. This command does not change the current filing mode, so if you have previously issued +MODEM, the DM24 will be left in FILING mode.
If you issue -MODEM over a dial-out modem link, you should make sure you have arrangements already in place for contacting the DM24 by other means, since the command will cause the connection to close.
Syntax: input-port +GCFIN
Instructs the digitizer to accept GCF input on either the GPS or the DATA IN port. input-port can be
1, for the GPS port, or
2, for the DATA IN port.
The GCF streams received will be combined with the DM24's own streams and output with them through the DATA OUT port or saved to Flash memory, according to the current filing mode.
Whilst GCF input is active, the normal function of each port (GPS or console access) is disabled.
Syntax: input-port -GCFIN
Instructs the digitizer to stop accepting GCF input on input-port, and to return that port to normal operation.
OPEN
Syntax:OPEN system-id stream-id-prefix (n.b.)
Opens a terminal session with a connected digitizer.
The DM24 scans all the ports which are currently accepting GCF input (see +GCFIN, above) to find a digitizer which matches system-id and stream-id-prefix.
For stream-id-prefix you should use the first 4 characters of the Stream IDs produced by this digitizer, i.e. without the component and tap designations.
A terminal connection is then made to the second digitizer, allowing you to issue commands.
To finish the session and return to the first digitizer's terminal mode, use the command GO.
This command is only available on units with the optional USB interface.
Syntax: port USBPORT
Instructs the digitizer to redirect input or output from port port to the USB interface. You can then attach the USB port to your computer with a suitable cable, where it will appear as an additional serial port with a significantly faster data transfer rate. port can be
0, for the DATA OUT port,
1, for the GPS port, or
2, for the DATA IN port.
The USB interface is provided by an internal FTDI245 chip, which is compatible with Microsoft Windows, Linux and Apple Macintosh systems.
You can only use the USB port to connect to a computer, not directly to a peripheral (e.g. a hard disk.) If you want to download data to a hard disk, you should specify the Firewire interface instead.
Syntax: tap-0 tap-1 tap-2 tap-3 samples/sec
The DSP software on the DM24 supports up to 7 cascaded filter/decimation stages. At each stage, the sample rate can be decimated by a factor of 2, 4 or 5. The ADC within the unit outputs data at 2000 samples/sec, so decimated data streams are available from 1,000, 500 and 400 samples/sec down to 1 sample/sec.
You can specify the sample rate to use at four of these stages, known as taps. You can also take output from any of these four stages. The DM24 will arrange the remaining stages according to your settings.
The arguments tap-0 to tap-3 are the sample rates at each tap in turn, starting with the highest. You must ensure that each rate is lower than the previous one by a factor of 2, 4, 5, 8 (= 2 then 4), 10 (= 2 then 5) or 16 (= 4 then 4). Non-integer values are not allowed.
For example:
1000 125 25 5 samples/sec
1000 500 100 10 samples/sec
500 100 20 4 samples/sec
400 40 10 5 samples/sec
As long as you specify the initial taps, you can omit later ones. The command fills in the value of the missing taps, using a decimation factor of 2 where possible. Thus, the following commands are equivalent:
400 40 20 10 samples/sec
400 40 samples/sec
Currently the DM software does not support the new GCF format for higher sample rates. It also does not properly support 250 samples/s, nor rates below 1 sample/s.
Syntax: tap components CONTINUOUS
Sets which components are output under normal conditions, and at which tap(s).
tap is the tap number at which to output the triggered stream. You can set which taps output which sample rate using the SAMPLES/SEC command, described above.
components is an integer below 16, whose binary bits represent the Z (1), N (2), E (4) and auxiliary (8) components respectively. Thus, for example,
0 1 CONTINUOUS will output the Z component only (1) at the first tap;
0 2 CONTINUOUS will output the N component only (2);
0 4 CONTINUOUS will output the E component only (4);
0 7 CONTINUOUS will output all three directional components (1 + 2 + 4 = 7);
0 12 CONTINUOUS will output the E component and the auxiliary component (4 + 8 = 12);
0 0 CONTINUOUS will output nothing at this tap.
Syntax: tap-0 tap-1 tap-2 tap-3 SET-TAPS
This is an alternative to the CONTINUOUS command, which allows you to set the outputs for all taps simultaneously.
tap-0 to tap-3 are integers below 16, whose binary bits represent the Z (1), N (2), E (4) and auxiliary (8) components respectively. Each one sets which components are output at that tap under normal conditions.
For example, if you issue
9 7 0 15 SET-TAPS
tap 1 will output Z and the auxiliary component ( 1 + 8 = 9 );
tap 2 will output all three directional components ( 1 + 2 + 4 = 7 );
tap 3 will not output anything; and
tap 4 will output all four components ( 1 + 2 + 4 + 8 = 15).
To set triggered output streams, you should use the TRIGGERED command detailed below.
Syntax: bits size COMPRESSION or NORMAL COMPRESSION
Sets the maximum amount of compression to use. Greater compression means the digitizer outputs data more efficiently, so more can be transmitted over a link with a given bandwidth. However, compressing streams uses processor power and can increase data latency.
The digitizer compresses data without loss, so compression is most effective when the data contains relatively little information. In most cases, when a seismic event occurs, the digitizer will need to decrease the compression level.
bits can be one of 8BIT, 16BIT and 32BIT. 8BIT (the default) is the maximum amount of compression; 32BIT denotes no compression.
size determines the maximum number of data samples in a GCF block. This must be between 20 and 250; the default is 250.
GCF blocks must be a whole number of seconds long. If you set size to a very small value, so that size samples is less than 1 second for some streams, the digitizer will output 1 block every second for those streams, ignoring the value of size.
Thus, if you issue 32BIT 20 COMPRESSION, streams with a sample rate of 20 samples/s and higher will output one block per second, whilst lower rate streams will output 20-sample blocks: every 5 seconds for 4 samples/s data, etc.
The special value, NORMAL COMPRESSION, returns the setting to its default value, and is equivalent to 8BIT 250 COMPRESSION.
LOWLATENCY
Syntax: LOWLATENCY
This is a special mode for applications requiring lower sample rate data in as close to real time as possible. In this mode, the digitizer takes a 200 samples/s stream and passes it through low-pass and decimation filters internally, before exposing it as a 20 samples/s stream at an increased rate of 1 block per second.
To enable low latency mode on all three components, first use SAMPLES/SEC to set Tap 0 to 200 samples/s, then issue the following commands:
NORMAL COMPRESSION
0 7 CONTINUOUS
0 1 BANDPASS
LOWLATENCY
7 TRIGGERS
If you want to enable low latency mode on some components only, replace the 7s above with another value (e.g. 1 = Z, 2 = N, 4 = E.)
To disable low latency mode, issue
0 1 BANDPASS
0 TRIGGERS
When LOWLATENCY is active, the TRIGGERS and BANDPASS commands have special meanings. Because of this, the STA/LTA triggering function is disabled. You can still use LEVEL triggering if you require (see below.)
SETDSS
Syntax: output-spec SETDSS
This command alters the way the DM24 outputs status streams.
In normal operation, the DM24 stores lines of status information until it has filled a 1K GCF block. For low latency applications, however, status information is required more frequently. In this mode, the DM24 will output a status block every minute. This mode is required by the DSS server distributed with Güralp Systems' CMG-DCM.
output-spec is an integer below 32, whose bits tell the digitizer which status lines to output.
Setting bit 0 (1) produces lines like
2006 9 4 13:13:00 2 MicroSeconds Fast Freq error 0 e-9
Auto 3D [-4]
showing the current internal clock offset, frequency error, and GPS fix type.
Setting bit 1 (2) produces lines like
2006 9 4 13:13:00 o/s= 340 drift= 0 pwm= 8382 Fix= "3D"
showing the current GPS offset, drift, PWM measure, and fix type.
Setting bit 2 (4) produces lines like
2006 9 4 13:13:00 Lat= "51'21.6526N" Long="001'09.8148W"
showing the GPS latitude and longitude.
Setting bit 3 (8) produces lines like
Boot Log : Power_cycles= 11 Watchdog_resets= 51
Last boot 2006 8 23 08:49:22 2006 8 23
08:50:40 Run 12Days 04:22:20
showing the number of times the digitizer has been reset, with the time of the last reset and the current up-time.
Setting bit 4 (16) produces lines like
2006 9 4 13:13:00 External supply : 14.3V Temperature
29.75'C
showing the current power supply voltage and temperature.
For example, issuing
6 SETDSS (= 2 + 4)
will cause the digitizer to begin outputting status blocks containing GPS timing and position information only:
2006 9 4 13:13:00 o/s= 340 drift= 0 pwm= 8382 Fix= "3D"
2006 9 4 13:13:00 Lat= "51'21.6526N" Long="001'09.8148W"
To use a DM24 with a DCM running a DSS server, you should issue
31 SETDSS
To return to normal operation, issue the command
0 SETDSS
Syntax: components TRIGGERS
Selects which component or components can generate an STA/LTA trigger. Only these components will be examined by the triggering algorithm.
components is an integer below 16, whose binary bits represent the Z (1), N (2), E (4) and auxiliary (8) components respectively as described above. Issuing 0 TRIGGERS will disable the triggering system.
When LOWLATENCY is active, this command is used to set the components which are output as low-latency streams. Issuing 0 TRIGGERS will disable the low latency mode.
GTRIGGERS
Syntax: components GTRIGGERS
Selects which component or components can generate a level trigger. Only these components will be examined by the triggering algorithm.
components is an integer below 16 with the same meaning as in TRIGGERS.
S/WTRIGGER
Syntax: S/WTRIGGER
Causes the digitizer to trigger immediately, and begin outputting triggered streams according to its configuration.
Syntax: tap components TRIGGERED
Selects which component or components will be output when a trigger is generated, and at which tap (sample rate).
tap is the tap number at which to output the triggered stream. You can set which taps output which sample rate using the SAMPLES/SEC command, described above.
components is an integer below 16, which represents which components to output in the same fashion as in the CONTINUOUS command, above.
(This command and the previous one have similar names; remember that a component TRIGGERS the system, whilst taps and components are TRIGGERED.)
Syntax: Z-secs N-secs E-secs X-secs STA
Sets the length of the “short-term” averaging period in the STA/LTA triggering algorithm.
Z-secs, N-secs, E-secs and X-secs are the time period over which to calculate the average for the Z, N, E, and auxiliary components respectively. If a component is not considered by the triggering algorithm (see TRIGGERS, above), the value you specify here will be ignored.
For example, 1 1 2 2 STA will calculate short-term averages over 1 s for the Z and N components, and over 2 s for the E and auxiliary components.
If you issue STA with only one argument, it is used for all four components. For example, 5 STA will calculate averages over 5 s of all components.
Syntax: Z-secs N-secs E-secs X-secs LTA
Sets the length of the “long-term” averaging period in the STA/LTA triggering algorithm.
Z-secs, N-secs, E-secs and X-secs are the time period over which to calculate the average for the Z, N, E, and auxiliary components respectively. If a component is not considered by the triggering algorithm (see TRIGGERS, above), the value you specify here will be ignored.
For example, 15 20 20 20 STA will calculate long-term averages over 15 s for the Z component, and over 20 s for the N, E and auxiliary components.
If you issue STA with only one argument, it is used for all four components. For example, 5 STA will calculate averages over 5 s of all components.
Syntax: Z-ratio N-ratio E-ratio X-ratio RATIOS
Sets the ratio of STA to LTA above which a trigger will be declared in the STA/LTA triggering algorithm.
Z-ratio, N-ratio, E-ratio and X-ratio are the time period over which to calculate the average for the Z, N, E, and auxiliary components respectively. If a component is not considered by the triggering algorithm (see TRIGGERS, above), the value you specify here will be ignored.
For example, 4 10 10 10 RATIOS will cause the DM24 to trigger if the STA/LTA ratio is above 4 for the Z component, or above 10 for the remaining components.
The arguments to this command must be integers. If you want to specify a fractional ratio, use the command FRATIOS instead.
Syntax: Z-ratio N-ratio E-ratio X-ratio FRATIOS
Sets the ratio of STA to LTA above which a trigger will be declared in the STA/LTA triggering algorithm.
This command is exactly the same as RATIOS, except that its arguments are divided by 10 before being entered into the system.For example, 25 100 100 100 FRATIOS will cause the DM24 to trigger if the STA/LTA ratio is above 2.5 for the Z component, or above 10 for the remaining components.
BANDPASS
Syntax: tap filter BANDPASS
Tells the DM24 which tap to use for STA/LTA triggering calculations.
Data is taken from this tap and passed through a band-pass filter before it is examined. This filtering maximises sensitivity within the frequency band of interest, and filters out noise outside this band.
The corner frequency of the band-pass filter depends on the values of tap and filter:
filter = 1 creates a filter with a corner at 10 % of the Nyquist frequency for tap tap (i.e. 5 % of its sample rate)
filter = 2 creates a filter with a corner at 20 % of the Nyquist frequency for tap tap (i.e. 15 % of its sample rate)
filter = 5 creates a filter with a corner at 50 % of the Nyquist frequency for tap tap (i.e. 25 % of its sample rate)
When LOWLATENCY is active, this command is used to set the tap used as the source of low-latency data. Data from this tap is decimated inside the DSP, and output on a separate stream at a rate 10 times slower than the configured rate.
MICROG
Syntax: level MICROG
Sets the output level above which a trigger will be declared in the LEVEL triggering algorithm. level is measured in counts.
HIGHPASS
Syntax: filter HIGHPASS
Instructs the DM24 to pass the stream(s) which generate LEVEL triggers through a high-pass filter before examining them. filter can be
1, for a 100 s high pass filter,
2, for a 300 s filter,
3, for a 1000 s filter, or
0, to disable the high pass filter.
Syntax: time PRE-TRIG
Sets the pre-trigger recording time. time is the number of seconds of data to output from before a trigger is declared.
Syntax: time POST-TRIG
Sets the post-trigger recording time. time is the number of seconds of data to output after a trigger condition lapses. If an event persists for some time, all triggering components must fall below the threshold before the trigger condition will lapse; only then will the post-trigger period begin.
Syntax: TRIGGERIN ENABLE | TRIGGERIN DISABLE
Enables or disables external trigger input, in instruments equipped with this option.
Enabling external trigger input allows you to trigger the DM24 from an external logic level supplied through its digital output port. This voltage can be between 5 and 10 V supplied between the Trigger In pin and signal ground. If the DM24 is triggered externally, it will behave exactly as if it had generated the trigger itself.
Syntax: TRIGGEROUT ENABLE | TRIGGEROUT DISABLE
Enables or disables external trigger output, in instruments equipped with this option.
Enabling external trigger output allows you to trigger other equipment through a relay contained within the DM24 whenever it triggers. The DM24's digital output port contains two pins (Trigger out, common and Trigger out, normally-open) which are connected when it triggers. In particular, you can connect a second digitizer with TRIGGERIN ENABLE in effect, in which case triggered data from both instruments will be transmitted whenever the DM24 triggers.
If a DM24 has both TRIGGERIN ENABLE and TRIGGEROUT ENABLE in effect, only triggers which the DM24 itself has generated will be output. Triggers received through the Trigger in port will cause the DM24 to output triggered streams, but will not be passed on to other digitizers.
POLARITY
Syntax: 0 POLARITY or 1 POLARITY
Sets the sense of the Trigger In pin on the DATA OUT port.
With 0 POLARITY set, the Trigger In pin is active low, i.e. a trigger will be generated if this pin is connected to ground. 1 POLARITY switches the pin to be active high.
You must issue TRIGGERIN ENABLE to enable external trigger input.
Syntax: component freq-or-period unit SINEWAVE
Instructs the DM24 to inject a sine-wave calibration signal, starting on the zero crossing.
component specifies which component is to be calibrated, one of Z, N/S, E/W, or ALL. Some sensors use only the Z calibration loop for all three components.
freq-or-period and unit together determine the frequency of the calibration signal. If unit is HZ, then freq-or-period is taken as a frequency, in Hz; if SECOND, then it is interpreted as a period, in s. For example:
N/S 4 HZ SINEWAVE
freq-or-period must be an integer; if you want to specify a period of, for example, 0.5 s, you should specify it as 2 HZ instead.
The calibration signal will be automatically disconnected after 2 minutes if you have not altered the setting using the MINUTE command, described below.
Whilst calibration is in progress, the fourth (auxiliary, or X) data channel is switched to monitor the returning calibration signal.
Syntax: component SQUAREWAVE
Instructs the DM24 to inject a square-wave (step function) calibration signal, consisting of a positive step on the start of the next clock minute, followed by a negative step some minutes later (by default, 2). The calibration is disconnected the same number of minutes after the negative edge.
component specifies which component is to be calibrated, one of Z, N/S, E/W, or ALL. Some sensors use only the Z calibration loop for all three components.
You can alter the duration of each step using the MINUTE command, described below.
Whilst calibration is in progress, the fourth (auxiliary, or X) data channel is switched to monitor the returning calibration signal.
Syntax: component RANDOMCAL
Instructs the DM24 to inject a white-noise calibration signal generated by an onboard pseudo-random number generator.
component specifies which component is to be calibrated, one of Z, N/S, E/W, or ALL. Some sensors use only the Z calibration loop for all three components.
The calibration signal will be automatically disconnected after 2 minutes if you have not altered the setting using the MINUTE command, described below.
Whilst calibration is in progress, the fourth (auxiliary, or X) data channel is switched to monitor the returning calibration signal.
The pseudo-random number generator produces true white noise over the entire passband, as shown in the power spectral density plot below:
The different coloured lines show the results of experiments which measure the power spectral density over several frequency bands. Together, the results show a flat noise level over the entire passband to within experimental error.
Syntax: duration MINUTE
Sets for how long the next SINEWAVE or RANDOMCAL calibration signal will be injected, or the period of the next SQUAREWAVE calibration signal.
duration is the desired interval, in minutes. If you now issue a SINEWAVE or RANDOMCAL command, the calibration will last duration minutes; if the next calibration command is SQUAREWAVE, a positive step of duration minutes will be generated, followed by a negative step of a further duration minutes.
If you do not issue MINUTE, calibration signals will default to 2 minutes.
Because of the way FORTH works, you can insert MINUTE commands into SQUAREWAVE, SINEWAVE or RANDOMCAL commands, for example:
N/S 4 HZ 5 MINUTE SINEWAVE
E/W 10 MINUTE SQUAREWAVE
Syntax: value %AMPLITUDE
Sets the relative amplitude of the signal, as a percentage. For SQUAREWAVE and RANDOMCAL calibrations, the default of 100% is normally suitable. If you have a high-gain sensor, you may have to use a lower value. For SINEWAVE calibrations, you may have to adjust the %AMPLITUDE setting to suit the frequency of the calibration signal.
You can insert %AMPLITUDE commands into calibration commands as described above, e.g.:
Z 3 MINUTE 50 %AMPLITUDE RANDOMCAL
Syntax: LOCK or LOCK MONITOR
Locks the sensor mass(es) of the instrument connected to SENSOR A.
If you issue LOCK, the command returns immediately, allowing you to close the terminal connection and follow the progress of the lock from the data streams.
If you issue LOCK MONITOR, the system displays the mass position for each component, measuring one position each second (i.e. one reading every 4 seconds for each component of a 4-component instrument.) The process returns when locking is complete.
The mass positions are measured to 16-bit accuracy, with full deflection corresponding to values around ±32000 counts.
Syntax: UNLOCK
Unlocks the sensor mass(es) of the instrument connected to SENSOR A.
UNLOCK returns immediately, whilst UNLOCK MONITOR monitors the progress of the unlock by displaying mass positions, as for LOCK MONITOR (above.)
Syntax: CENTRE
Centres the sensor mass(es) of the instrument connected to SENSOR A.
CENTRE returns immediately, whilst CENTRE MONITOR monitors the progress of the unlock by displaying mass positions, as for LOCK MONITOR (above.)
When the masses are correctly centred, the mass positions should read less than ±1000 counts.
MASSES?
Syntax: MASSES?
Begins reporting the current mass positions for all three components, once per second, until you press a key. Mass position information is also output on Mux channels M8, M9 and MA, if you have enabled them.
Over time, and especially if the temperature changes significantly, the sensor masses may drift off centre. If this is not corrected, velocity output will eventually be lost.
%AUTO-CENTRE
Syntax: distance %AUTO-CENTRE
Instructs the DM24 to perform a round of centring whenever a mass position drifts further than distance from zero. distance is measured as a percentage of full scale.
Setting distance to zero disables automatic centring.
Syntax: component value O/SNULL
Remove any DC offsets in a stream by applying a counter-offset in software. As manufactured, for technical reasons, the ADC nulling offset is set to around 75000 counts. You should only need to change this if the digitizer's CMOS RAM becomes corrupted; it is always better to zero the instrument by levelling and centring as far as is possible, or by adjusting potentiometers (in sensors where these are present.)
component specifies which component to adjust: 0, 1, 2, and 3 denote the Z, N, E and X components of SENSOR A, and 4, 5, 6 and 7 are the corresponding components of SENSOR B.
value specifies the adjustment to apply to the component.
This command is in the extended dictionary: to use it, first type ok-1 and finish with [seal].
This command is only available in units with a precision real-time clock module fitted.
Syntax: RE-SYNC ON|OFF
RE-SYNC ON instructs the DM24 to resynchronize the real-time clock module to GPS time when a GPS fix is next obtained.
RE-SYNC OFF cancels a previous RE-SYNC ON instruction, so that attaching a GPS module will no longer cause the DM24 to resynchronize.
This command is only available in units with a precision real-time clock module fitted.
Syntax: ?LITHIUM
Query the current status of the RTC's internal battery. This command is in the extended dictionary: to use it, first type ok-1 and finish with [seal].
Syntax: RE-BOOT (interactive)
Causes the DM24 to reset after a delay of 2 s.
RE-BOOT
Confirm with 'y' ? y
Responding to the confirmation message with anything other than y will abort the reset.
Syntax: SHOW-FLASH
Reports status information about the Flash memory in the DM24, if fitted. For example:
SHOW-FLASH for a new system with 8 × 64Mb chips fitted:
512MB Flash File buffer : 16 Blocks Written 0 Unread 524,288 Free
Oldest data [16] Blank
Read point [16] Blank
Latest data [16] Blank
File Replay [16] Blank
SHOW-FLASH for a system in use with 1 × 64Mb chip fitted:
64MB Flash File buffer : 65,536 Blocks Written 65,532 Unread 4 Free
Oldest data [36,272] GURALP TESTZ1 2003 12 3 20:20:41
Read point [36,272] GURALP TESTZ1 2003 12 3 20:20:41
Latest data [36,268] GURALP TESTX2 2003 12 4 10:09:12
File Replay [36,272] GURALP TESTZ1 2003 12 3 20:20:41
The first line displays general status information, namely the quantity of Flash memory available (64MB Flash File buffer), how many 1k GCF blocks have been written (65,536 Blocks Written), how many remain to be transmitted (65,532 Unread), and how much space (in 1k blocks) remains (4 Free).
The next lines show, in turn,
the stream and timestamp of the oldest data in memory,
the current position of the read pointer,
the stream and timestamp of the latest data in memory, and
the current position of the replay point.
The read pointer normally points to the oldest data in the file; however, if all the data up to the replay point has already been downloaded, the read pointer is set to the replay point and the number of blocks remaining Unread is updated. Downloads where a time-period is not specified always start from the read pointer.
RESET-FLASH
Syntax: RESET-FLASH
Resets the Flash memory pointers. The DM24 will start overwriting old data from the beginning of memory. You can still access this data, if it has not been overwritten.
Syntax: ERASEFILE (interactive)
Removes all data from the Flash memory, and resets all pointers to the beginning. You will be asked for confirmation before you do this, as all data will be destroyed.
If you have been running the DM24 with a Firewire disk attached, remember that there will be some data still in Flash memory awaiting transfer, up to the amount you last set with MBTRANSFER. You should make sure this data is transferred with the DISKMENU command before you ERASEFILE.
Depending on the amount of Flash memory installed, ERASEFILE may take several minutes to complete.
Syntax: event-specification EVENTSLIST
Displays details of triggered events. event-specification can have several forms:
RECENT, to display the most recent events. By default, 16 events are displayed. You can double or halve this number by prefixing RECENT with either SHORTER or LONGER. You can use several of these commands, e.g.
LONGER LONGER RECENT EVENTSLIST
will display 64 events. The DM24 remembers this setting, so a further LONGER RECENT EVENTSLIST would display 128 events.
EARLIER, to display the previous set of events of the currently-configured length, e.g. if RECENT EVENTSLIST displays the 16 events #30 to #45, EARLIER EVENTSLIST will display the 16 events #14 to #29.
COMPLETE, to display all events currently held in Flash memory.
yyyy mm dd hh mm SEARCH, to look for events in the 10-minute period defined by yyyy mm dd hh mm, e.g.
2005 12 26 04 13 SEARCH EVENTSLIST
will display events between 04:10 and 04:20 on 2005-12-26. The time format is the same as for FROM-TIME and TO-TIME, above.
If an event occurs, but nothing is filed (e.g. because the digitizer is in DIRECT mode), it will be listed with the message No File.
two numbers event-id number-of-events, to display number-of-events starting at event number event-id.
RESET-LIST
Syntax: RESET-LIST
Empties the events list. You will no longer be able to see event information with the EVENTSLIST command, or download events with EVENTS (see below.)
This command does not delete any data. If you empty the events list, and the digitizer is in a suitable filing mode, you can still download event data using the commands in Section 5.10, “Downloading over the serial port“.
Syntax: DIRECT
Instructs the DM24 not to use Flash memory for storage. Instead, all data is transmitted directly to clients. A temporary RAM buffer allows clients to request blocks they fail to receive using the Block Recovery Protocol.
Syntax: FILING
Instructs the DM24 not to transmit blocks to clients, but to store all digitized data in the Flash memory. The memory is used in circular fashion, i.e. if it becomes full, incoming blocks begin overwriting the oldest in memory.
Syntax: DUPLICATE
Instructs the DM24 to transmit all new data directly to clients (as in DIRECT mode) as well as storing it in Flash memory (as in FILING mode). If a client fails to acknowledge a block, the digitizer does not attempt to retransmit it.
DUAL
Syntax: DUAL
Instructs the DM24 to transmit any continuous streams directly to clients (as for DIRECT mode) but to store triggered data into Flash storage (as for FILING mode.)
If you choose this mode, the instrument will send heartbeat messages in addition to any continuous streams you have configured. Scream! can pick these up and download new data as necessary.
Syntax: ADAPTIVE
Instructs the DM24 to transmit current blocks to clients if possible, but to store all unacknowledged blocks in the Flash memory and re-send them when time allows. This differs from DIRECT in the following ways:
the client does not have to keep track of which blocks it has not received, and
the entire Flash memory can be used for blocks awaiting retransmission, rather than a temporary RAM buffer.
Adaptive mode is best suited for installations where the link between digitizer and client is intermittent or difficult of access.
Syntax: FIFO
Instructs the DM24 to begin writing new blocks to Flash memory as for FILING, but also to transmit data to clients. Data is transmitted in strict order, oldest first; the DM24 will only transmit the next block when it receives an acknowledgement of the previous block. Once a block is transmitted, it is marked as such in the Flash memory, and may be overwritten later.
Syntax: interval HEARTBEAT
When the DM24 is in FILING mode, it outputs status messages periodically over the RS232 port (see Section 6.1, page 82.) This command changes how often these messages are produced.
If the digitizer has been configured to dial out over a modem link (see +MODEM, above), it will dial out whenever it generates a heartbeat message.
interval is measured in units of 30 ms. For example, issuing
600 HEARTBEAT
will cause the DM24 to output heartbeat messages every (600 × 30) = 18000 ms = 18 s.
Alternatively, you can insert the word HOUR and specify interval in hours:
5 HOUR HEARTBEAT
The maximum value allowed for HEARTBEAT is 300 000 000 (= 2500 HOUR).
If you connect to a digitizer in FILING mode using Scream!, Scream! will not detect the digitizer until it has sent a heartbeat message. Therefore, you should use a relatively short heartbeat interval if you have a continuously-connected instrument.
MS-GAP
Syntax: interval MS-GAP
Sets the interval the digitizer should wait for a GCF ACK (acknowledged) message, before assuming that the block could not be transmitted.
If a period of interval passes without an acknowledgement, the digitizer's behaviour depends on the current filing mode (see above.)
interval is measured in milliseconds. The default is 150. If the value is greater than the average time between blocks being generated, and an outage occurs in the return communications link, the digitizer will be producing data faster than it can transmit it, and gaps will start to be observed. However, systems using slower communications links (e.g. radio links) may be unable to acknowledge blocks in under 150 ms. You should choose a value for interval which is suitable for your particular installation.
RE-USE
Syntax: RE-USE
Instructs the DM24 to use its Flash memory as a circular buffer, overwriting the oldest data when it becomes full.
In this mode, the Flash memory will always contain the latest data.
WRITE-ONCE
Syntax: WRITE-ONCE
Instructs the DM24 not to overwrite data in the Flash memory when it becomes full Instead, when the digitizer runs out of space, it switches to DIRECT filing mode and will leave the Flash memory untouched.
MODE?
Syntax: MODE?
Displays the current disk usage mode (RE-USE = Circular; WRITE-ONCE = Write Once.)
Syntax: DOWNLOAD
Sets up a data transfer from the Flash memory over the serial connection. Which data is downloaded depends on various parameters you can set, which allow you to select a particular stream, streams of a specified sample rate, or streams within a certain time window. You can set parameters separately, or string the definitions before the DOWNLOAD command, e.g.
ALL-FLASH STREAM HPA0N1 DOWNLOAD
2004 12 01 00 00 FROM-TIME ALL-DATA DOWNLOAD
100 S/S ALL-TIMES DOWNLOAD
DOWNLOAD (starts another download with the same parameters as last time)
See below for full details of the parameter commands.
The DOWNLOAD command returns immediately, so that you can issue more commands if required. To close the connection and begin downloading, issue the GO command. You can pause the download by entering terminal mode, and restart with another GO or abort with END-DOWNLOAD.
Syntax: ALL-FLASH
Sets the read point to the oldest data held by the DM24. This command does not alter which streams are to be transmitted; you should specify streams or use the ALL-DATA command in addition to this one.
Syntax: ALL-DATA
Instructs the DM24 to transmit all the data streams it holds next time a DOWNLOAD is issued. This command does not alter the read point or time period; you should specify a time period or use the ALL-FLASH command in addition to this one.
Syntax: STREAM stream-id (n.b.)
Instructs the DM24 to transmit only the stream with ID stream-id. Stream IDs are normally a 4-character device code (e.g. HPA0) followed by a component letter (N) and a tap number (1).
Unlike most FORTH commands, the stream-id parameter goes after the command.
Syntax: STATUS-ONLY
Instructs the DM24 to transmit only status streams (text streams, normally with stream IDs ending in 00.)
Syntax: rate S/S
Instructs the DM24 to transmit only streams with sample rates equal to rate. If rate is zero, only status streams are transmitted.
Note that this command should not be confused with the SAMPLES/SEC command.
Syntax: ALL-TIMES
Clears any time selection in force, allowing you to download all data held by the DM24. This command does not alter which streams are to be transmitted; you should specify streams or use the ALL-DATA command in addition to this one.
Syntax: yyyy mm dd hh mm FROM-TIME
Instructs the DM24 to transmit only data more recent than yyyy-mm-dd hh:mm, where
yyyy is a four-digit year (1989 – 2069);
mm is the month number (1 – 12);
dd is the day of the month (1 – 31);
hh is the hour of the day (0 – 23); and
mm is the minute of the hour (0 – 59).
Syntax: yyyy mm dd hh mm TO-TIME
Instructs the DM24 to transmit only data older than yyyy-mm-dd hh:mm, where yyyy, mm, dd, hh and mm have the same meanings as in FROM-TIME, above.
Syntax: event-specification EVENTS
Instructs the DM24 to transmit only data recorded during triggered events. event-specification can have several forms:
RECENT, to download the most recent events. By default, 16 events are displayed. You can double or halve this number by prefixing RECENT with either SHORTER or LONGER. You can use several of these commands, e.g.
LONGER LONGER RECENT EVENTS
will download 64 events. The DM24 remembers this setting, so a further LONGER RECENT EVENTS would download 128 events.
EARLIER, to download the previous set of events of the currently-configured length, e.g. if RECENT EVENTS downloads the 16 events #30 to #45, EARLIER EVENTS will download the 16 events #14 to #29.
COMPLETE, to download all events currently held in Flash memory.
yyyy mm dd hh mm SEARCH, to look for events in the 10-minute period defined by yyyy mm dd hh mm, e.g.
2005 12 26 04 13 SEARCH EVENTS
will download events between 04:10 and 04:20 on 2005-12-26. The time format is the same as for FROM-TIME and TO-TIME, above.
If an event occurs, but nothing is filed (e.g. because the digitizer is in DIRECT mode), it will be listed with the message No File.
two numbers event-id number-of-events, to download number-of-events starting at event number event-id. You can find out event-id using the command EVENTSLIST (above.) Thus, if EVENTSLIST returns
# 7 Filed @ 63,772 PLPGG SBHYZG 2006 1 4 16:07:50
# 8 Filed @ 63,812 PLPGG SBHYZG 2006 1 4 16:22:24
# 9 Filed @ 63,952 PLPGG SBHYZG 2006 1 5 10:14:59
# 10 Filed @ 64,005 PLPGG SBHYZG 2006 1 5 10:16:49
# 11 Filed @ 64,039 PLPGG SBHYEG 2006 1 5 10:17:45
you can instruct the digitizer to download these 5 events with the command
7 5 EVENTS
Once you have specified the events to be downloaded, issuing DOWNLOAD will make the DM24 begin transmitting data as soon as your terminal session is ended.
Syntax: GO
Closes terminal mode, and begins the download you have set up. You can pause the download by re-entering terminal mode, and restart with another GO or abort with END-DOWNLOAD.
Once the download has completed, the DM24 will carry on transmitting real-time data, if you have so configured it.
Syntax: END-DOWNLOAD
Aborts any downloads which were in progress at the time you entered terminal mode.
Syntax: DISKMENU (interactive)
Allows you to select various options for downloading data over the optional FireWire interface. When you issue this command you will see the message
Plug in FireWire cable
and the DM24 will wait for you to plug in a compatible disk. When it detects one, it will print out information about the disk:
FireWire Connecti