Troubleshooting By Symptom - Mitsubishi Electric MELSEC iQ-R Series User Manual

27.3

Troubleshooting by Symptom

The troubleshooting for any troubles generated during communication between C24 and the target device by trouble symptom
are as shown below.
When any trouble occurs, check on the C24 condition at first, and check the relevant item in the table below.
Symptom
*1
LED turns ON or flashes
Communication error occurred
Communication via modem cannot
*3
be established
The programmable controller CPU
monitoring function does not operate
in the specified cycle
Data cannot be received by an
interrupt program
The initial setting cannot be
configured
*1 For details on LED status, refer to the following manual.
MELSEC iQ-R Serial Communication Module User's Manual (Startup)
*2 For details on how to check the hardware information communication error, refer to the following section.
Page 441 Checking error status
*3 If an error occurs while performing data communication using the modem function, first check the following items and determine whether
or not the error is caused by the modem/TA connection.
If an error relating to the modem function occurs, take corrective actions according to the following items shown below:
 Check of the ON/OFF status of current input/output signals on C24
 Check of the error code storage status for the modem function
 Check of the ON/OFF status of the DR terminal on the modem/TA (Refer to the instruction manual for modem/TA.)
Symptom description
Page 459 SD LED does not flash even after a send request was
made
Page 459 RD LED does not flash even though the target device is
transmitting a message
Page 460 No response message is returned even though the
target device transmitted a message and the RD LED flashes
Page 461 Read request signal does not turn ON even though the
target device transmitted a message and the RD LED flashes
Page 462 The CPRTCL instruction execution is not completed
although the RD LED flashes
Page 463 RUN LED turns OFF
Page 463 ERR LED flashes
Page 464 ERR LED turns ON
Page 465 C ERR LED turns ON
Page 466 Hardware information communication error "SIO"
*2
occurs
Page 467 Hardware information communication error "PRO."
*2
occurs
Page 468 Hardware information communication error "P/S"
*2
occurs
Page 468 Hardware information communication error "C/N"
*2
occurs
Page 469 Hardware information communication error "NAK"
*2
occurs
Page 469 Communication is intermittent
Page 470 Undecodable data are transmitted or received
Page 471 Whether the communication error is caused on C24 or
target device is unclear
Page 471 Communication is not established via modem
Page 472 Communication is not established with the ISDN sub-
address when using a modem
Page 472 Fixed cycle send is not performed normally
Page 472 Condition match send is not performed normally
Page 472 Data cannot be received by an interrupt program
Page 472 Data cannot be written to flash ROM
Protocol
MC Nonpro Bidirec
cedural tional
  
  
 
 
  
  
  
  
  

  
  

  
  
  
  
 
 
 
 
  
27 TROUBLESHOOTING
27.3 Troubleshooting by Symptom
Predefi
ned
27














457