Guralp Systems Limited
MAN-C24-0001 - CMG-CD24 Operator's Guide


1. Introduction 2. Setting up the CD24 3. Configuration & Control with Scream! 4. CD24 5. Command line interface 6. Updating the CD24 7. Appendices 8. Revision history

Section Index: 2.1. Connectors 2.2. Test installation 2.3. Setting up the Ethernet or wireless interface 2.4. Configuring the digitiser 2.5. Downloading data over FireWire 2.6. Receiving data in Scream!

Chapter 2. Setting up the CD24

This section gives an overview of how to set up a CD24 and begin recording data. We recommend that you set up a test digitiser in your office or laboratory as a “dry run” to gain a basic understanding of the system and to check that it is functioning as expected.

This test installation will use the digitiser's default settings. Data will be received using Güralp Systems' Scream! software, available from the website:

2.1 Connectors

The CD24's output connectors are located on the lid. The sensor input is located on the side. The digitiser can be supplied with a number of options, so not all the connectors may be present on your digitiser. The input connector is configured to connect directly to one of GSL's sensors and has all the necessary power and control functions.

All CD24s have a 19-pin mil-spec connector on the lid for connection to a supplied breakout box with the following connections:

You may need to attach a suitable connector to the power cable provided. The CD24 draws a nominal current of 55 mA from a 12 V supply when in use; thus, using a 12 V, 25 Ah sealed heavy-duty lead-acid battery, you should expect the digitiser to operate for more than a week without recharging.

The CD24 may also have connectors for the FireWire, Ethernet or Wi-Fi interfaces.

2.2 Test installation

To test the CD24, you will need access to a PC with a 9-pin serial port (RS232), a 12 V power source and a working sensor (e.g. CMG-3ESP, ESPC, 40T or 6T).

Install Scream! on your PC and run it.

Connect the wire from the breakout box to the CD24's 19-pin connector labelled: POWER DATA GPS.

Connect the 6-pin connector on the breakout box to the GPS unit using the GPS cable. Position the GPS so that it has a good view of the sky.

Note: If you do not have a view of the sky, you can operate the CD24 without a GPS unit, but timing information may be inaccurate.

Connect the sensor to the 26-pin connector on the side of CD24.

Connect the 6-pin data plug on the breakout box to the 9-pin serial port on your PC using the serial cable.

Use the power cable to connect the 10-pin power plug on the breakout box to a fused 10 – 28 V power source.

The CD24 and instrument are now fully operational and will already be producing data.

After a few seconds, you should see the CD24 digitiser appear under Network – Local – COM1 in the left-hand panel of Scream!'s main window. (If your PC has multiple serial ports, it may appear under some other COM port name.) Soon after, data streams will begin appearing in the right-hand panel. Streams with higher sample rates will appear sooner than those with lower sample rates:

If this does not happen, check all connections, and ensure the power supply is providing the correct voltage and current.

Each data stream has a Stream ID, a six-character string unique to it. Stream IDs normally identify the instrument, component and sample rate of each stream. Thus the stream 1026Z2 refers to a Z-component stream from instrument 1026, at tap 2. For more details on taps and sample rates, see section 3.1.2, page 27.

Data streams ending in 00 are status streams containing any extra information sent from the digitiser.

To view data, select a stream and then double-click to open a Waveview window.

You can view several streams at once by holding down SHIFT as you select, and then double-clicking the selection.


To start recording new data to a file, right-click on a stream or a selection of streams and choose Start recording from the pop-up menu. Recording settings, directories, etc., can be altered by selecting File → Setup... from the main menu and switching to the Recording tab.

To view status information, select the stream and right-click to open a pop-up menu. Select View.

The first few status blocks will consist of the CD24's start-up messages, including its software revision number and the data streams selected for downloading and triggering.

Later blocks give information on the GPS system (number of satellites visible, the location of the GPS antenna, time synchronization status, etc.) and the baud rates in use for each channel.

For more information on SCREAM! refer to the user manual available from the Güralp Systems' website:

2.3 Setting up the Ethernet or wireless interface

CMG-CD24 digitisers with Ethernet or Wireless features installed use an embedded Lantronix Wi-Port module to provide the network interface. Configuration of the Ethernet or Wireless interface is made using the Lantronix' DeviceInstaller utility for Microsoft Windows, using a DHCP server or the via the serial port. You will need a PC with a network or wireless interface installed or an RS232 connector,

You may find it easiest to gather together all the Wi-Fi hardware before taking it into the field and configuring it from a local wireless-enabled PC.

There are two types of wireless network topology supported by the Wi-Port.

2.3.1 Using DeviceInstaller

2.3.2 Using DHCP

If you cannot install DeviceInstaller on your PC, or you do not wish to, you can also get access to the CD24 using a standard DHCP server. In most cases you will need to have administrative privileges to do this.

2.3.3 Configuration with the web interface

Once you have access to the Wi-Port's Web interface, you can configure it with its proper settings. Wireless Settings Configuring the serial channels

2.3.4 Installing wireless hardware

The small antenna supplied with the CD24 is adequate for initial testing or temporary installations with an access point within 50m of the digitiser.

To send data over a larger distance, or if the line of sight between the antenna and the access point is blocked, you will need to use a larger and more powerful antenna.

In infrastructure mode, you can reduce the power requirements by using a directional antenna pointed at the location of the access point. The access point does not need to be permanently present. For example, you could set up an array of CD24 digitisers with antennas pointed towards a prominent natural feature with line of sight to all the digitisers, and access them all from this location using a laptop PC.

2.4 Configuring the digitiser

Autonomous CD24 installations will need to be configured before deployment. You can do this either

Both methods provide full access to the configuration options of the CD24.

In particular, the CD24 can operate in a number of transmission modes. These modes determine whether the unit stores data in its on-board Flash memory, sends it over the serial link in GCF format, or does some combination of these. See section 3.2.5 for more details.

2.5 Downloading data over FireWire

The easiest way to download data over FireWire is to connect a suitable disk to the FireWire port of the CD24 and power-cycle the unit.

If you have ordered a CD24 with the powered FireWire option, you can attach the disk directly to the CD24 with no additional connections. Otherwise, you will need to connect the disk to a power source through the supplied adapter.

When the digitiser restarts, it will automatically detect the disk and flush all new data to it.

If you do not want to restart the digitiser, you can also flush data to disk manually:

2.5.1 Reading CD24 disks

The CD24 uses a special disk format, DFD, for recording data. This format is also used by other Güralp digitisers such as the DM24.

You can read these data into a PC using Scream! or the Windows gcfxtract utilities, which are freely available from the Güralp Systems' web site. Linux and Solaris command line utilities are also available for reading data from a DFD disk.

The DFD format is not the same as that used by the Güralp Systems EAM data module, which uses either a FAT32-compatible journalling file system or an ext3 file system.

Güralp Systems can provide fully tested disks with FireWire and USB connectors. Alternatively, a third-party FireWire disk may be used (although compatibility is not guaranteed.) Reading CD24 Disks using SCREAM!

To read a disk with Scream!:

2.6 Receiving data in Scream!

There are several ways a CD24 digitiser can be connected to Scream!:

To connect to a CD24 over the network:


1. Introduction 2. Setting up the CD24 3. Configuration & Control with Scream! 4. CD24 5. Command line interface 6. Updating the CD24 7. Appendices 8. Revision history