Watlow MLS-PM, User Manual

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Troubleshooting
MLS User’s Guide 111
Keys Don't Respond
If the MLS seems to function perfectly, but the Man/Auto, Chng SP,
Alarm Ack, and Ramp/Soak keys do not respond when you press
them, then you are probably locked out of the system. Ask your
supervisor to unlock the keyboard according to the instructions in the
Setup Global Parameters section.
Controller Message: AIM Comm Failure
If you power up the MLS-PM and the message AIM COMM FAIL
appears, or if the LED on the AIM is not blinking, check the following:
• Make sure power supply connections are correct (see the Power Wir-
ing and Controller Test section of the Installation chapter).
•
Make sure the AIM Communications cable is plugged into the AIM
and the connector labeled "TO AIM" on the MLS-PM.
If the AIM COMM FAIL message still appears, perform a manual
controller reset. If the MLS still does not power up with the Bar Graph
Display, return the unit to ANAFAZE for repair.
Checking Analog Inputs
If the number of inputs recognized by the MLS-PM does not agree with
the number of inputs in the MLS-AIM, perform a manual controller
reset with the AIM connected to the processor module. If the numbers
still don't agree, check the following:
Make sure the input wires are properly connected. Every input on
the MLS-AIM has three screw terminals: positive, negative, and
auxiliary. All T/C, milliamp, and voltage inputs connect to the positive
and negative terminals. RTD inputs connect to all three terminals.
Check for high common mode voltage. It is not uncommon for heaters
to leak into the T/C wires. Use an AC Voltmeter for testing.
If the inputs are not reading properly, make sure you have selected
the correct input type from the Setup menus (see Chapter 4: Setup).
Checking the Operation of an Input
• Disconnect the sensor wiring.
• Set the input sensor to type J T/C from the Setup menus.
• Place a short across the input.
The process variable should indicate ambient temperature. If it does not,
call ANAFAZE for an RMA number and return the unit for repair.
If the process variable indicates ambient temperature, then the MLS is
working correctly and the problem lies in the sensor or sensor wiring.
You can test T/C or RTD sensors with a Multimeter.