A Measured Temperature Value Is Not Converted To An Expected Value; A Measured Temperature Value Fluctuates; Conversion Completed Flag Does Not Turn On - Mitsubishi Electric MELSEC iQ-R Series User Manual

A measured temperature value is not converted to an expected
value
Check item
Check whether the input range setting is correct.
Check whether the offset/gain setting is correct.
Check whether the set temperature conversion method is correct.
Check whether the setting of 'Cold junction compensation with/without setting'
(Un\G298) of the thermocouple input module is correct.

A measured temperature value fluctuates

Check item
Check whether a temperature conversion method other than sampling
processing is set.

Conversion completed flag does not turn on

Check item
Check whether all channels are set to be conversion disabled.
Check whether disconnection of a cold junction compensation resistor (RTD)
is detected in the thermocouple input module.
3 TROUBLESHOOTING
82
3.3 Troubleshooting by Symptom
Action
Check that the set input range is corresponding to the connected
thermocouple or connected resistance temperature detector using the
following buffer memory areas.
• Thermocouple input module: 'CH1 Range setting monitor (Thermocouple
type)' (Un\G430)
• RTD input module: 'CH1 Range setting monitor (Resistance temperature
detector type)' (Un\G430)
If the input range setting is not correct, set "Thermocouple type setting" or
"RTD type setting" of Module Parameter again.
Check that the offset/gain setting is correct. If the user range setting is used,
change it to the other input range and check that the temperature conversion
is performed correctly.
When the temperature conversion is correct, perform the offset/gain setting
again.
Check that the set temperature conversion method is correct using 'CH1
Averaging process specification' (Un\G501).
If the temperature conversion method is not correct, set "Average processing
setting" of Module Parameter again.
Check 'Cold junction compensation setting status' (Un\G61). When performing
the cold junction compensation using a cold junction compensation resistor
(RTD), set "Cold junction temperature compensation with/without setting" of
Module Parameter to "With cold junction temperature compensation". When
performing the cold junction compensation using an external method, set
"Without cold junction temperature compensation".
Action
Check if Sampling processing (0) is set in 'CH1 Averaging process
specification' (Un\G501).
If Sampling processing (0) is set, correct the settings of Module Parameter as
described below, and check for fluctuation of values in 'CH1 Measured
temperature value' (Un\G400).
• Set "Average processing setting" to a value other than "Sampling
processing".
• Set "Time average/Count average/Moving average/Primary delay filter
constant setting" according to the setting of "Average processing setting".
Action
Check CH Conversion enable/disable setting of all channels. If a channel
where the conversion is enabled does not exist, set "Conversion enable/
disable setting" of any channel of Module Parameter to "Conversion enable".
Eliminate the cause of disconnection, by replacing the cold junction
compensation resistor (RTD) for instance, and check 'CH1 Measured
temperature value' (Un\G400).