User's Manual

102 LEDR Series I/O Guide MDS 05-3627A01, Rev. D
When you set up a system, you must be careful to avoid an infinite loop.
If echo is enabled, then every character that enters the Service Channel
port will be echoed back out the port. When echo is disabled then data
that comes in the Service Channel port is not sent back out the port.
Trouble may arise if the device that is connected to the Service Channel
also echoes the data it sends. In that case, the device will send characters
into the Service Channel Port, the radio will echo the characters back to
the device, the device will consider the echoed data to be input which it
will in turn echo back to the radio, etcetera, until an overflow condition
occurs.
You must also set the communication parameters (baud rate, stop bits,
char length, and parity) via the
svch subcommands so that the settings
match those at the device connected to the Service Channel Port.
Lastly, the user can re-initialize the Service Channel port via the
svch
reset
command. This may be helpful in the case where an infinite loop
overflow condition has locked the port.
10.3 Usage
The Service Channel supports ASCII data transfer over the network in
broadcast fashion. As a result, devices connected to the Service Channel
Ports of different radios will appear to have a transparent half-duplex
connection between them.
10.4 NMS Commands
This command is used to set/display Service Channel parameters.
Usage:
svch [subcommand] [<argument>]
Subcommands:
baud
char
echo
off
off
on
parity
reset
stop
on
—Enable the Service Channel
off—Disable the Service Channel
reset—Re-initialize the Service Channel
echo—on/off
baud—300, 600, 1200, 2400, 4800 and 9600
char— 5, 6, 7, 8 (ASCII character length in bits)
parity—none, even, odd
stop—1, 2 (Stop bits)