39 PRECAUTIONS ON PROGRAMMING
39.1 Instructions Not Available in System Using SIL2 Process CPU
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39
■REMTO instruction
When the system switching is performed while the instruction is being executed (M101 = ON), SM1643 (ON for only one scan
after system switching (standby system to control system)) will turn on for one scan in the new control system and the REMTO
instruction will be executed again on the station number 10 of the network number 1. When the system switching is performed
while a write instruction such as the REMTO instruction is being executed, execution of the instruction may have been
suspended before completion of writing data to the target module. Thus, insert an interlock in the new control system to read
the X signals and buffer memory status of the target module and to determine whether or not to execute the instruction again.
• Devices used
*1 For details on the link special relay (SB) and link special register (SW), refer to the manuals for the network used.
*2 Change the device number according to the system.
• Program example
Device Description
SM1643 ON for only one scan after system switching (standby system to control
system)
SB47
*1
Baton pass status of own station
SW0A0.9
*1
Baton pass status of each station
M100
*2
Write request
M101
*2
At instruction execution
M102
*2
ON at instruction re-execution request due to system switching
M103
*2
Completed without an error
M104
*2
Completed with an error
(1) Add an interlock circuit for determining whether or not to execute the instruction again (according to the X signals and buffer memory status of the target
module) as required.
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