3 connecting to a single computer – Guralp Systems CMG-DCM User Manual

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CMG-DCM Data Communications Module

possible, since it is easy to accidentally short the pins of a male

connector. Attached digitizers and sensors are powered from the same
supply as the DCM. Any 12 V DC power supply may be used; if using

batteries, we recommend that you use a unit with low-voltage
disconnect to avoid excessive drain.

rack-mounted DCM has a separate POWER IN connector on the back

panel, which should be attached to a 12 V DC supply. There is also a

POWER OUT connector on this panel, which allows you to daisy-

chain several DCM units together. The

POWER OUT connector is

provided merely for convenience: lines from the

POWER IN connector

pass straight through.

integrated DCM receives its 12 V DC power from two pins in its

single connector. See Chapter 9, page 127, for the positions of these

pins.

2.3 Connecting to a single computer

In autonomous or temporary installations, you will only need to

connect the DCM to one computer (

e.g. a laptop) for initial

configuration. Follow these instructions to make the DCM

communicate with your computer.

Note that your computer must either have an RS232 (serial) port for
initial connection, or be running its own DHCP server. DHCP servers

are available for Windows, but are not supplied as standard.

If you want to connect the DCM to a local area network, follow the
instructions in Section 2.4, page 15, instead.

Connecting over a serial link

The

DATA OUT port can be used to connect a DCM to a single

computer through a direct serial link. This link can be used to log in to

the Linux operating system of the DCM and transfer files. It is most
useful for maintenance and troubleshooting over a low-bandwidth

connection, and for initial setup.

To communicate over a serial link:

1. Connect an RS232 reverse serial cable between the DCM and

your computer. A suitable cable should have been supplied with

the unit.

2. Run a terminal emulation program on the computer. The built-

in programs minicom for Linux, and hypertrm for Microsoft

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