A Multi Function Counter Does Not Start Counting Or Does Not Count Properly - Mitsubishi Electric MELSEC-L Series LD40PD01 User Manual

A multi function counter does not start counting or does not
count properly
The module does not start counting
Check item
Has Count Enable been set to ON?
Is any LED of the CPU module indicating an error?
Is the external wiring for ΦA and ΦB correct?
Is the control of the hardware logic working?
Are the block layout and links between blocks in the hardware logic correct?
The module does not count properly
Check item
Are the current value or other values read in increments of one word (16 bits)
using a program when 32-bit counter timer blocks are used?
Was the preset function performed within the count range of a counter?
Is the filter time setting of external input blocks correct?
When the same pulse is input to the multi function counter blocks that have
the same links, is the same value counted?
Does the input pulse wave satisfy the performance specifications?
Is the external wiring with the SSI encoder correct?
Is the setting value of the SSI encoder block correct?
Is the cable length within the range of the maximum cable length?
Are shielded twisted pair cables used?
Does noise affect anything?
Is there a sufficient distance between the high voltage device and the signal
wires?
14 TROUBLESHOOTING
236
14.5 Troubleshooting by Symptom
Action
Set Count Enable to ON using a program or the configuration tool.
If the LED indicates an error, refer to the troubleshooting in the manual for the
CPU module used and take corrective actions to restore normal operation of
the CPU module.
Check the external wiring and make necessary corrections.
When Hardware logic control flag (X4) is off, turn on Hardware logic control
start request (Y4) to start the hardware logic control.
Check the block layout and links between blocks in the hardware logic and
make necessary corrections.
Action
Read the values of two words (32 bits) in a batch.
Reset the preset value within the count range and perform the preset function
again.
Check the filter time setting and make necessary corrections.
If the count values are different, the possible cause is a failure of the module.
Please consult your local Mitsubishi representative.
Observe and check the pulse wave with a synchroscope. If the input pulse
does not satisfy the performance specifications, input pulses that satisfy the
performance specifications.
Check the external wiring. ( Page 55 Example of external wiring with the
SSI encoder (serial communication))
Check and correct the value according to the SSI encoder to be connected.
Check the cable length and size. ( Page 55 Example of external wiring
with the SSI encoder (serial communication))
Or slow the SSI transmission speed.
Use shielded twisted pair cables.
Take measures to reduce noise such as attaching a surge suppressor to the
magnet switch.
Wire the signal wires alone and keep them 150mm or more away from power
cables.