When A Digital Output Value Cannot Be Read - Mitsubishi Electric MELSEC iQ-R User Manual

When a digital output value cannot be read

Follow the steps in the table below to find the cause of the trouble.
Description
■Step 1: Checking the digital output value
Check the following.
• Check whether digital output values have
been stored in the buffer memory.
• Check whether the program for reading
digital output values has an error.
■Step 2: Checking the conversion status
Check the execution status of the A/D
conversion in the module, such as whether
the A/D converter module have executed
the A/D conversion.
■Step 3: Checking the input range setting
Check whether the input range appropriate
to the analog input is set.
*1 Monitor the buffer memory areas using "Device/Buffer Memory Batch Monitor" or "Intelligent Function Module Monitor".
If digital output values cannot be read even after the above actions are taken, the possible cause is a failure of
the A/D converter module. Please consult your local Mitsubishi representative.
3 TROUBLESHOOTING
156
3.3 Troubleshooting by Symptom
Procedure
When digital output values
cannot be read
Check the stored value in
'CH1 Digital output value' (Un\G400).
Are the stored
digital output values corresponding
to the analog input?
NO
Ò
Ò
Check the stored value in 'CH1 A/D
conversion status monitor' (Un\G459).
Is "A/D conversion disable (1)" stored?
NO
Ó
Ó
Check the stored value in 'CH1 Range
setting monitor' (Un\G430).
Is the set input range
matched with the
analog input?
NO
The analog input is not matched with the
input range setting.
Check item 4
Monitor the buffer memory area with the
*1
monitor function of the engineering tool.
The read program has an error or the
CPU module is in STOP status.
YES
Check item 1
Monitor the buffer memory area with the
*1
monitor function of the engineering tool.
A/D conversion is not enabled.
YES
Check item 2
Monitor the buffer memory area with the
*1
monitor function
Check and correct the wiring and
YES
offset/gain setting.
Check item 3
of the engineering tool.