Guralp Systems Limited

Chapter 1. Introduction

The CMG-DCM is a versatile Linux-based module for storing and transmitting data captured using Güralp Systems Limited's range of seismic measuring equipment. GCF data can be gathered from up to three compatible digitizers or digital instruments, and stored in its on-board Flash memory, from where it is written from time to time to a USB hard disk or to another device on your network. Once data is on the hard disk, you can connect to the DCM in various ways to retrieve it.

Depending on your site requirements, the DCM may be supplied in several formats. Although these look different, they all share the same internal features.

A DCM in any of these forms may be supplied in the configuration most suitable to your requirements, depending on how you wish it to be connected to your network, and how its USB interface is to be used. The two sets of options are independent.

Whichever set of options you choose, you can use any free RS232 port to connect the DCM to a single computer for local monitoring and configuration, or through it to a wider network using PPP/SLIP.

1.1 Inside the DCM

The DCM's configuration is maintained by an internal database. All of the flexibility of the unit is provided through this configuration database. Before you deploy the DCM, you will need to configure it for your needs, either using its on-board Web server or over a direct serial link.

The two main areas which need to be configured determine the different services which the DCM provides from its serial and network ports.

Serial port services

You can use either the DCM's console or its Web configuration interface to configure the serial data ports. The serial.x.service configuration option determines which service each port provides.

Network services

Because the DCM is a fully-fledged Linux machine, you will need to set up networking before you can use it. Advanced networking is beyond the scope of this manual. For a basic setup, you will need to perform the following actions:

See Section 2.4, page 15, for full details.

Once you have connected the DCM to your local network or to the Internet, you can use a wide range of methods to retrieve data from it.

In addition, the DCM can be configured to act as a data client, receiving GCF and CD1.0/1.1 data streams, combining these streams and storing or retransmitting them as appropriate. See Chapter 3, page 24, for full details.