Guralp Systems CMG-DCM - Manual (Page 84)

CMG-DCM Data Communications Module
modem which is operating in raw mode ( i.e. which does not
support the standard AT modem commands.) This option in
runs the Linux command mgetty -r. A port running the
mgetty-r service will also listen for incoming PPP frames, and if
it detects one will configure the PPP link according to the
/etc/mgetty+sendfax/login.config file (see Section 6.11,
page 100.)
•
ppp : The port will provide a PPP link to a connected computer.
Once set up on the computer, the DCM will appear as if on a
local TCP/IP network. You can then log in to it using
ssh or use
its Web-based administration system, as well as receiving data.
Before a PPP link will function, you will need to specify the PPP
options and (if using CHAP) provide a chap-secrets file. This
can be done through the DCM configuration interface: see see
Section 6.11, page 100. Also see the Linux manual page for
pppd(8) for an explanation of how PPP is implemented.
•
gcf_in : The port will receive data from a GCF-compatible
digitizer.
•
gcf_out : The port will send GCF data directly to the connected
device as it is received. A number of programs are available for
PCs which handle incoming GCF data streams, such as Scream!,
Antelope, and Earthworm. The DCM transparently merges all
incoming data streams, so if you are using Scream!, you can also
configure and control attached digitizers using its own interface.
•
cnsn_in : The module will use this port to receive raw data
using the CNSN protocols. If you use this service, there must be
exactly one cnsn_in and one cnsn_out port.
•
cnsn_out : The module will this port to transmit authenticated
data using the CNSN protocols. If you use this service, there
must be exactly one cnsn_in and one cnsn_out port.
•
dss_sum : The port will transmit DSS summary data. Which
data is transmitted depends on the value of serial.x.dss, below.
serial.x.baudrate : This option alters the speed of communication
across each serial link, in bits per second.
For ports connected to digitizers, you should ensure that the baud rate
is high enough to allow all the data to be transmitted at the rates you
have chosen. As an example, for three streams transmitting at 100 Hz,
a rate of 9600 baud is usually sufficient. Modern modems can
84 Issue F