Eaton MTL83*C Modbus Software Manual

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Eaton MTL83*C Modbus Software Manual Manual pdf 17 page image

13INM MTL83xC PC Modbus Rev 1DRAFT - 06 January 20195 2 11 Alarm Relay 1There are 10 alarm conditions that can be used to trigger the alarm relay. If multipleconditions are selected, then they are logically OR’d together. Check the checkboxof the condition(s) that you want to trigger the alarm. The gray box to the left of thecheckbox indicates the way the currently connected MTL838C is configured.If the “Comm Errors” condition is selected, the “Comm Errors Per Hour Threshold”is enabled. Once programmed, the MTL838C will turn the relay ON when theselected number of Comm Errors Per Hour is exceeded.Use the “Delay” field to require that the alarm condition must exist for thisnumber of seconds BEFORE the alarm will be triggered. If “Comm Errors” or“Hardware Failure” is checked and one of these occurs in the unit, the alarm will tripimmediately (the Delay is ignored for these error conditions).The “Stick on” parameter forces the relay to stay ON this number of minutes AFTERthe alarm condition has cleared.The following table describes the different alarm conditions:Comm Errors Comm Errors are caused by the MTL838C getting CRC errorsin transmissions from the MTL831C(s) or the MTL831C(s) missresponding to a command 3 times in a row (this triggers a Commre-initialization with that MTL831C).Hardware Failure Two possible conditions will cause this condition. First, everyminute the 838C verifies that the CRC of the configuration data isgood. A difference causes the error to be set – it is never reset.Secondly, there are two board temperature sensors that are usedfor cold junction compensation (CJC) for thermocouples. If they aredifferent by more than 5°C, the error is set – otherwise it is reset.TC Burn Out If a thermocouple (TC) has increased in resistance by 50 ohms, itis considered close to burning out and this error is set. See thediagnostic tab to see what the TC resistances are.TC Intermittent A thermocouple is intermittently opening (could be a bad connectionor it is broken).TC Open A channel configured as thermocouple is open.mV Open A channel configured as mV is open.RTD Open A channel configured as RTD (2 wire, 3 wire, or 4 wire) is open.RTD Miswired A 3 wire or 4 wire RTD is not wired correctly. Note that some waysof miswiring 3 and 4 wire RTDs cannot be detected (typically readnear zero ohms in this case).High Alarm A channel reading exceeds the High Alarm threshold (see MTL831C#1 or #2 tabs).Low Alarm A channel reading is below the Low Alarm threshold (see MTL831C#1 or #2 tabs).