Q-Controller System Operation Manual
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86550-001-000 Rev B
6 MODBUS Protocol Supported By Q-Controller
For Modbus protocol, please contact QEL.
7 Troubleshooting Hints
Q-Controller has advanced features and functions. Before assuming that unexpected behavior is caused by
a system defect or breakdown, the operator should use this manual to become thoroughly familiar with the
Q-Controller operation. This troubleshooting guide is intended as an aid in identifying the cause of
unexpected behavior and determining whether the behavior is due to normal operation or an internal or
external problem.
SYMPTOMS
PROBABLE CAUSE
SUGGESTED SOLUTION
LCD Display does not
come on
•
No power supply
•
LCD has problem
•
Program has crashed
•
Check power / ground connections
•
Change LCD
•
Reprogram
RS-485
RX LED or
TX LED constantly ON
•
RS-485 bus connection has
problem
•
RS-485 Driver is damaged
•
Remote Device side RS-485
Driver has problem
•
Disconnect the Cable to isolate the
problem
•
Replace Driver on main board
•
Replace RS-485 Driver in Remote
Device
Q-Controller
reports
“Vote no Sensor!” or “AV
no Sensor!”
•
No sensor was assigned to the
output (relay or analog output)
•
Assign sensor to the output
Q-Controller
reports
“Sensor
Offline”
or
“Relay Offline”
•
Comm setting is wrong
•
Connection is wrong
•
Remote Device is in Fault
•
End-of-line matching resistors
are not properly set.
•
Check the remote baud rate in Q-
Controller System Setting is same
as the baud rate in Digital Sensor
or M-Relay.
•
Check connection between Q-
Controller and Digital Sensor and
M-Relay. Make sure all have
power on and no shorts or opens in
wiring. Be certain that polarity for
RS-485 connections is correct. A-
A and B-B
•
Examine remote devices
•
Review
end-of-line
resistor
settings
