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7.3
Installation Troubleshooting, Modems or DSUs
First, set up the DSUs without connecting the multiplexers. The host
DSU should be set to constant carrier, also called forced Request To
Send, or constant RTS. The remote DSUs must be set to Request To
Send controlled by the terminal. In this case, the SPL Drop
multiplexer.
Carrier Detect should be ON at all the remote drops, even before the
SRX Host and the SPL Drops are connected.
Carrier Detect should be OFF at the host, with or without SPL Drops
connected at the drop sites. For testing the line and DSUs only, you
may wish to momentarily force Request To Send on at a remote DSU to
see if it results in Carrier Detect turning on at the host.
7.4
Installation Troubleshooting, Multiplexers
Before trying terminals, make sure the multiplexers are polling. The
SRX Host should be polling the SPL Drop multiplexers. The host DSU
Send Data, Receive Data and Carrier Detect lights should be flashing.
The polling on DSUs is often so fast that the lights appear to be
constantly on, but dimly. Use the “SS” command from the Network
Management port for a quick check. See paragraph 5.4.9.
Double check the SPL Drop multiplexers. Insure you have drop
firmware installed and the address is set correctly. See paragraph 4.1.1
of the SPL Multidrop manual for address information.
Make sure the SRX host is properly mapped. An SPL Drop must be
mapped in the host before it will be polled and become active.
7.5
Installation Troubleshooting, Terminals
Terminal problems typically fall into four categories:
1.
The terminal or printer gets no data
2.
The terminal or printer gets “garbage” data
3.
Blocks of data are lost
4.
Terminals or printers seem to “hang”.
When a terminal gets no data, check to see the cables are wired
correctly and that flow control is set properly.
