Receive Data Clear - Mitsubishi Electric MELSEC iQ-R Series User Manual

Receive data clear

For the data reception using the nonprocedural protocol, if the transmission of data from a transmitting device is interrupted
due to any trouble, clearing the data received up to the present time on the receiving device side and receiving again from the
first data may be required.
The methods for clearing received data in the C24 are shown below.
Use any of the methods to clear received data as necessary.
• Receive data clear request by the dedicated instruction "CSET" (Page 67 Receive data clear with dedicated instruction
"CSET")
• Write to/read from the 'receive data clear request' (Un\G168/328). (MOV instruction) (Page 69 Receive data clear with
MOV instruction)
• Receive data clear request with Engineering tool. (Page 73 Receive data clear request procedure using Engineering
tool)
Precautions
When transmitting data to a target device from C24, do not execute a clear request of the receive data with Engineering tool.
If a receive data clear request is executed when transmitting data to a target device, C24 stops data transmission and
terminates the dedicated instruction for transmission abnormally. (The transmission completion signal does not turn ON.) If a
receive data clear request is executed during data reception, the data received up to that point are cleared.
Receive data clear processing
C24 performs the following processing when the receive data clear is performed.
• C24 regards the received data up to the present time as invalid data.
• C24 clears the receive data quantity up to the present time to "0". (The receive area in the buffer memory is not initialized).
• C24 sets the status in the one prior to the start of data reception.
Procedure for clearing the received data by the program
Using the following instructions, clear the received data by a program.
• Dedicated instruction "CSET"
• MOV instruction
For the procedure to clear received data by a program, refer to the following.
Receive data clear with dedicated instruction "CSET"
This instruction clears the received data up to the present time without interrupting the data transmission processing.
For details on CSET instruction, refer to the dedicated instruction. (Page 520 Dedicated Instructions)
■Procedure for clearing (For the CH1 side interface)
 If the CSET instruction is executed while the 'CH reception data read request' (X3/XA) or 'CH reception abnormal
detection signal' (X4/XB) is ON, the CSET instruction is kept waiting until the signal is turned OFF.
 The receive data clear processing is executed to the OS area of the C24. (Page 58 Receive data arrangement)
3 DATA COMMUNICATION USING NONPROCEDURAL PROTOCOL
3.1 Receiving Data from Target Device
3
67