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Terminals/PC Problems
If your terminal or PC connection is not working properly, symptoms are usually no output at
all, 'garbage' on the screen, loss of characters or ports locking. Here is the common solution
checklist to these problems:
Problem
Cable error
Port settings incorrect
No flow control
Port flow controlled
Wrong flow control
Faulty terminal
Wrong port on terminal
Faulty Server port
Cable too long
Terminal Server User Guide
Terminals/PC Problems
Action required
Replace the cable with a known good one or test the cable ends.
Check the wiring against Appendix C, Cabling Guide. This is the
number one problem. It is helpful to have a null modem cable and a
RS-232 mini-tester.
Check the set-ups of your unit and the terminal ensuring that they are
the same at both ends. Check parity, bps rate, flow control, data bits
and stop bits.
Set flow control to be the same at both ends and ensure that the
cable installed is capable of supporting it.
It is possible that an XOFF character has been received by
mistakenly typing or other condition. Power the terminal off and on
and type.
If the XON and XOFF characters are configurable on the terminal
check that they are set to (0x11) and (0x13). If the application you are
using is transferring binary data then software flow control cannot be
used as some of the binary data may be interpreted as flow control
characters.
Try a known working terminal on the port.
Many terminals have more than one port (i.e. AUX). Check that the
cable has been connected to the correct port.
Try a known working terminal on the suspect port. If possible, attach
a serial line monitor. If the area you are working in is prone to
electrical storms, it is possible that a high voltage surge has been
induced in the cable and damaged the driver/receiver chips within
the unit.
The RS-232 specification states a maximum length of cable
proportional to the bps rate. A good rule of thumb is that a 19200 bps
connection should not be used on cable lengths in excess of 15m
(50 ft). Also a 9600 bps signal operates reliably up to a distance of
approximately 30m (100 ft). Cables of greater lengths may seem to
work correctly but the connection will be less reliable.
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