Guralp Systems CMG-DCM - Manual (Page 18)

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