Troubleshooting Control Unit IV Reference Manual
6-8 529-0004 Ver.3
3. To check that the Control Unit is able to receive commands, connect a terminal to
COM 3 and use the
?
command. The Control Unit’s
RX
/
TX
3
LED should flicker. If the
Control Unit seems to respond to requests transmitted by the terminal (one of the
RX
/
TX
LEDs lights up), but no commands are displayed on screen, you may have a problem
with the terminal’s setup. Make sure that you have enabled local echo display (see
Chapter 2). Note that the Windows 98 version of HyperTerminal does not support local
echo display. Use another version instead, or any other communication software.
4. If the problem persists, contact Electroline’s technical support department.
6.4 Troubleshooting redundancy system errors
Before testing the Control Units in a redundancy system, check the cabling and ensure that
both Control Units have the exact same setup. You can easily solve many problems by
checking the following:
1. Make sure the units are cabled as shown in the redundancy connection diagram in
Chapter 2.
2. Connect a terminal to the master Control Unit’s COM 3 port and open a session. Type
info
and note the setup shown in the system screen. Repeat this step on the backup unit.
Both units should have the same setup (see Chapter 3 for a checklist).
3. If both units do not have the exact same setup, log on to a setup session and change any
parameters that are not the same. See Chapter 3 for detailed setup instructions.
4. After making a change to the setup in a redundancy system, you must always restart the
units in order to reset the redundancy circuitry (see section 6.4.3).
5. If the redundancy system continues to malfunction, note the error messages that appear
on screen or the codes sent to the host computer, and use the corresponding procedures to
correct the problem.
6.4.1 COM ports in a redundancy system
In a redundancy system, the Control Unit uses each COM port for a specific purpose. The
troubleshooting help in the following sections applies only to redundancy systems.
COM 1
The master Control Unit receives data from a host computer, such as a billing system, on the
unit’s COM 1 port, and sends an acknowledge message back to the host computer. The
backup unit also receives data from the host computer on its COM 1 port, but it will not
transmit any data as long as it is the backup unit. The
RX
/
TX
1
LED lights up on both units,
even though only the master unit transmits data.
If the redundancy cable is not connected properly, communication problems may occur, such
as collisions, between the Control Unit and the host computer.
Check the redundancy cable. If the problem persists, contact Electroline’s technical support
department.
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