29 PRECAUTIONS ON PROGRAMMING
29.1 Instructions Not Available in Redundant System
503
29
Instructions that need to be executed again in a new control
system
For an instruction that requires several scans for completing the processing, the instruction will be continuously executed
when the system switching is performed during execution of the instruction. When a completion device has been used in an
execution program of the control system, the completion device will not turn on even though the instruction is completed after
the system switching from the control system to the standby system. However, the completion device will turn on after the
system switching from the control system to the standby system and then to the control system again. Note that the
completion state of the completion device is not reflected to the tracking device. When the system switching is performed
during execution of an instruction, execute the instruction again as required.
For some instructions, an error will occur if an instruction is executed during execution of the same instruction. For the
operation for each instruction that is executed again during execution of the same instruction, refer to the following.
MELSEC iQ-R Programming Manual (CPU Module Instructions, Standard Functions/Function Blocks)
MELSEC iQ-R Programming Manual (Module Dedicated Instructions)
Classification Instruction symbol
Data processing instructions SORTD(_U), DSORTD(_U)
Reading/writing data instructions SP.DEVST, SP.FREAD, SP.FWRITE
Open/close processing instructions SP.SOCOPEN, SP.SOCCLOSE
Socket communications instructions SP.SOCRCV, S.SOCRCVS, SP.SOCSND, SP.SOCCINF, SP.SOCCSET,
SP.SOCRMODE, S(P).SOCRDATA
SLMP frame send instruction SP.SLMPSND
File transfer function instruction SP.FTPPUT, SP.FTPGET
Module dedicated instructions Instructions that require several scans for completing processing
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