Eaton MTL831C, Instruction Manual

10

INM MTL831C Rev 7

9 

START UP AND INFREQUENT MEASUREMENTS

The MTL831C/MTL831C-PS enters a startup process after power is applied.  Normal 
operation begins about 60 seconds after power is applied.  Thermocouple resistances 
(for burnout detection) and CJC (Cold Junction Compensation) temperatures are 
being measured frequently during startup.  Afterwards these measurements are 
made infrequently (on the order of minutes).  See section 4.5 for information on 
Thermocouple Burnout Detection.

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FAULT-FINDING IN THE MTL831C/MTL831C-PS

The following are some tips when the system does not seem to be functioning 
correctly.  If you are still unable to solve the issue, please contact Eaton Technical 
Support for help.

The POWER light is not ON or blinking

•  There is not adequate power for the unit to function.  Using a Voltmeter,  

measure the voltage at the data highway “+” and “-“ terminals and verify  

that it meets the minimum voltage specification.  A margin of at least 1 volt  

over the minimum is recommended.

•  The unit is faulty.  Please contact Eaton for further assistance.

The COMM light comes on and does not blink

  • Two 

MTL831C/MTL831C-PSs are at the same address.  If there is more than  

  one 

MTL831C/MTL831C-PS (there should never be more than 2), one and  

only one of them should have a jumper wire between the two ADDRESS  

pins (A, S).  When two MTL831C/MTL831C-PSs are at the same address  

whichever one powers up first will be communicating with the MTL838C.   

The other unit recognizes its address already being used and remains idle.

•  No communication signal is getting to the MTL831C/MTL831C-PS.  There can  

be multiple reasons for this:

•  In an IS installation, power for the MTL831C/MTL831C-PS is coming from  

  the MTL5553.  

  If the MTL838C is not powered or not connected properly no signal will  

  get to the MTL5553 to be passed to the MTL831C/MTL831C-PS is.

•  For non-IS installations, power comes from the MTL838C, so it is  

  possible the MTL838C has stopped communicating.  Investigate by  

  connecting to the MTL838C with a USB cable, PC, and the PC Software.   

  It may be necessary to repower the MTL838C.

    • The 

MTL831C/MTL831C-PS has stopped receiving communication.  Try  

  disconnecting it and reconnecting it to reboot it. The data highway cable  

  is too noisy for the MTL831C/MTL831C-PS to communicate with the  

  MTL838C.  Inspect the data highway cable run and make sure it is not  

  near power cables, VFDs, VFD controllers, or other high current noise  

  producing cables and equipment.

•  The unit is faulty.  Please contact Eaton for further assistance.

The ERROR light comes on periodically

•  The light flashes regularly every one or two seconds.  If this persists,  

you may see the unit reboot – see section 6.1.  Power cycle the unit by    

disconnecting and reconnecting the data highway cable if this happens    

and keeps recurring. The failure of a firmware update process which would  

have been initiated from the PC software could also cause this.  The  

solution would be to try the firmware update process again.  If that fails to  

remedy the issue, the unit could be faulty.  Contact Eaton for assistance.

•  The light flashes randomly or often.  This is likely a CRC error on packet  

receipt (bad packet).  The following are the potential causes: