Mitsubishi Electric MELSEC iQ-F FX5 User Manual page 415

■When the ALM LED turns on or flashes
• When it is on
Check item
Check whether any alert has been issued.
• When flashing
Check item
Check whether any disconnection has been occurred.
■When a digital output value cannot be read
Check item
Check whether an analog signal line is disconnected from the multiple input
module.
Check whether a thermocouple and compensation lead wire are correctly
connected.
Check whether the CPU module is in the STOP state.
Check whether the offset/gain setting is correct.
Check whether the input type/input range setting are correct.
Check whether 'Operating condition setting request' (Un\G70, b9) has been
executed.
Check whether the setting value of the time average is correct when the time
average is selected in Averaging process specification.
*1 The conversion does not start when 'Operating condition setting request' (Un\G70, b9) is on. After turning offon, check that 'Operating
condition setting completed flag' (Un\G69, b9) is off, and then make sure to turn onoff.
■Digital output value does not vary
Check item
Check whether disconnection of a thermocouple or compensation lead wire is
detected.
Corrective action
Check Alert output flag (Process alarm upper limit), Alert output flag (Process
alarm lower limit), Alert output flag (Rate alarm upper limit), and Alert output
flag (Rate alarm lower limit).
Take actions described in the list of alarm codes.
Page 417 List of alarm codes
Corrective action
Check Disconnection detection signal or Disconnection detection flag.
Take actions described in the list of alarm codes.
Page 417 List of alarm codes
Corrective action
Visually check signal lines and correctly connect analog signal lines.
Correctly connect a thermocouple or compensation lead wire to the multiple
input module. The following is the check point.
• A shielded cable for the used channel is grounded or not.
• The thermocouple and compensation lead wire are reversely connected or
not.
Change the state of the CPU module to RUN.
Check that the offset/gain setting is correct.
If the user range setting is used, change to the factory shipment setting, and
check that the conversion is performed.
When the conversion is correct, perform the offset/gain setting again.
Check 'CH1 Input type/Range monitor' (Un\G430) with GX Works3. When the
input type/input range setting are incorrect, reconfigure the input type and
input range setting again.
*1
Turn offonoff 'Operating condition setting request' (Un\G70, b9) and
check that a digital output value is stored in 'CH1 Digital output value'
(Un\G400) using GX Works3.
When the time average is selected for processing, set the time average value
in CH1 Time average/Count average/Moving average setting so that the value
satisfies the following condition:
• Time average setting value  4 (times)  40 (ms)  Number of Input type
thermocouple/resistance temperature detector specified channel
If the condition above is not satisfied, the digital output value results in 0.
Corrective action
Eliminate the cause of disconnection, by replacing the thermocouple or
compensation lead wire for instance, and check 'CH1 Digital output value'
(Un\G400).
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3.10 Troubleshooting
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