Reception Error Detection And Check Methods - Mitsubishi Electric MELSEC iQ-R Series User Manual

Reception error detection and check methods

The following explains how to detect and confirm errors that may occur when receiving data from target devices.
The possible primary causes of errors during data reception are shown below.
Cause of reception error
A transmission error occurred due to noise.
A timeout occurred for the no-reception monitoring (timer 0).
Data that could not be converted using the ASCII-BIN conversion is included.
Data larger than the size that could be stored in the OS area of C24 is received.
Detection/checking of reception error by a program
■Detecting a reception error
The following device and input signals turn ON.
• INPUT instruction completion device + 1
• 'CH reception abnormal detection' (X4/XB)
• 'CH Error occurrence' (XE/XF)
■Checking a reception error
The reception error code can be checked using the INPUT instruction control data ((S1) + 1).
Or, it can be checked by reading the 'data reception result' (Un\G600/616).
For details on how to check the error code contents and corrective actions, refer to the following section.
Page 473 Error Code List
Detection/checking of reception error with module and Engineering tool
■Confirmation using the indicator LED
When C24 detects an error, including a transmission error, the ERR LED turns ON.
■Confirmation using Engineering tool
Monitor the 'data reception result' (Un\G600/616) to check the error code.
Considerations
The following describes the considerations for received data in case of errors.
■Storing received data
The received data for which an error was detected is discarded and only the normally received data is stored in C24.
Thus, there may be missing data among the data that has been read to the CPU module when a reception error occurs.
■Reading received data
When receive data is read to the CPU module by turning the 'CH reception abnormal detection' (X4/XB) ON, the data that
was normally received prior to the error detection is read.
Read and discard received data as needed.
3 DATA COMMUNICATION USING NONPROCEDURAL PROTOCOL
3.1 Receiving Data from Target Device
Reference
MELSEC iQ-R Serial Communication
Module User's Manual (Startup)
Page 228 No-reception Monitoring
Time (timer 0) Setting
Page 348 ASCII-BIN Conversion for
Data Communicated with
Nonprocedural Protocol
Page 58 Receive data arrangement
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