Omron C200HW-PRM21 Operation Manuals page 105

Troubleshooting
Message Communication problems
Description
IOWR instruction Output mailbox is full. The Output mailbox is
not successfully not able to process new command messages
executed when the Input mailbox is not able to receive
reply messages.
The RUN-bit (IR n.00) is not switched ON or
the communication is inhibited (IR n.01)
The IOWR instruction contains syntax errors
The transferred command message is not
correct.
Note:
The Master Unit is faulty
IORD instruction not There is no reply message in the Input mailbox
successfully
executed
The IORD instruction contains syntax errors
The Master Unit is faulty
Command was not Issued more than one IOWR per PLC scan or
successfully issued an IOWR after issuing a control
executed though command via the control words in the previous
IR n+2.12 (Output PLC scan. In both cases, IR n+2.12 has not
mailbox full) is not been updated and the mailbox could just have
set. been filled up and be unable to process more.
For other reasons see situation 'IOWR
instruction not successfully executed'
IORD command Issued more than one IORD per PLC scan or
was not executed issued an IORD after issuing an 'Input mailbox
successfully though clear' command via the control words in the
IR n+2.13 (Reply in previous PLC scan. In both cases IR n+2.13
input mailbox) was has not been updated and the Input mailbox
set. could just have been cleared.
For other reasons see situation 'IORD
instruction not successfully executed'
ERR LED is A fatal error is detected. The cause is reported
switched ON in IR n+2.06 ~ IR n+2.08
Possible cause
This error can not be detected by the
result of the EQ-flag!
Possible remedy
Clear the messages in the Input mailbox to
enable the Input mailbox to receive new
messages and the Output mailbox to process
new messages. The messages can be
cleared by using IORD instructions or by
setting IR n.01 of the control words.
Set the RUN-bit and enable communication
again.
Check the IOWR instruction. Is the correct
Unit number and message length specified?
Check the command message that is created
in the PLC data area. Does it comply with the
command messages definition specified in
section 6-4?
Replace the Master Unit.
Only read a message when IR n+2.13 (Reply
in input mailbox) is set.
Check the IORD instruction. Are the correct
Unit number and message length specified?
Replace the Master Unit.
Do not issue more than one IOWR per PLC
scan or do not issue an IOWR after issuing an
control command via the control words in the
previous PLC scan.
-
Do not issue more than one IORD per PLC
scan or do not issue an IORD after issuing an
'Input mailbox clear' command via the control
words in the previous PLC scan.
-
Try to solve the cause and / or restart the
Unit. If this does not help, replace the Master
Unit
Section 7-2
89