User's Manual

B-7
RS-422 Termination
When adding Relays to a system, the last Relay(s) in the line(s) must be
terminated. By default, all Base stations and Relay are shipped as terminated.
Use the following guidelines to change the termination for your system:
Refer to the circuit board diagram on the previous page for details.
• If the Base has multiple strings of relays radiating from it, the Base
would not be terminated but each Relay would.
• If the Base is first in a string, (not in the middle or end of a string), set
the 422 jumpers to Base w/RS-422 termination.
• The last Relay in each string should have its jumpers set as a Relay
w/RS-422 termination. Any Relay that is not the last relay in the
string would not be terminated.
Relay Station failures are often cable-related. If a Terminal puts out a
“Who Can Hear Me?” message and a Relay that is for some reason not
connected to the Base Station (bad cable, cut cable, broken connectors)
hears it, it answers with the message:
Relay n Cannot Be
Heard by the Base
Notify Supervisor
Press Any Key
At this point, it is up to the operator to notify someone that the Relay is not
communicating with the Base and to check the cabling first. There is no
message sent to the host, so it is very important that the operator that
receives this message notify someone immediately.