CMG-DCM / AM - Güralp Systems Limited
CMG-DCM / AM - Güralp Systems Limited
CMG-DCM / AM - Güralp Systems Limited
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>CMG</strong>-<strong>DCM</strong> Data Communications Module<br />
and one using 802.11 connections, or a mixture of the two.<br />
Once the 802.11 system is running, you will need to run a DHCP<br />
service on your network, or manually set the IP address of the <strong>DCM</strong> as<br />
above.<br />
Connecting to the Internet<br />
If the local network is already connected to the Internet through some<br />
other means (perhaps through a gateway machine), you can create a<br />
default route with<br />
gcfgdbset net.eth.0.gateway network-gateway<br />
where network-gateway should be replaced with the IP address of<br />
the gateway on your local network.<br />
The <strong>DCM</strong> can perform more complex routeing if required. See “Static<br />
routes”, page 80, for more details.<br />
As supplied, the <strong>DCM</strong> module will accept requests to its on-board Web<br />
server and logins over SSH. In addition, the <strong>DCM</strong> can be requested by<br />
Scream! or other GCF-compatible software to send GCF streams to<br />
your computer.<br />
If the instrument is located on a private network, you may be able to<br />
connect to it from the wider Internet by using a feature implemented<br />
by SSH known as tunnelling. You can use this technique to connect to<br />
the <strong>DCM</strong> through a chain of intermediate machines which support<br />
SSH. Once this chain is set up, you can treat the connection as if it<br />
were a direct link between the <strong>DCM</strong> and your computer. Many<br />
standard Internet protocols may be fed through SSH in this manner.<br />
Whether this is possible will depend on the precise configuration of<br />
your local area network. For more details, please see the<br />
documentation for SSH clients such as ssh and putty.<br />
2.5 Connecting digitizers and external hardware<br />
The <strong>DCM</strong> is designed for use with <strong>Güralp</strong> <strong>Systems</strong> digitizers, which<br />
communicate over RS232 or RS422 serial links using the GCF protocol.<br />
There are three RS232 ports available on a stand-alone <strong>DCM</strong> and ten<br />
on a rack-mounted model, whilst on a <strong>DCM</strong> bonded to a digitizer unit<br />
only the DATA OUT port is available (the digitizer is connected<br />
directly to the PORT A interface).<br />
The three serial ports on a stand-alone <strong>DCM</strong> are labelled DATA OUT,<br />
PORT A, and PORT B. In a typical setup, one or both of the latter two<br />
18 Issue F