Precautions For Dedicated Instructions - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Precautions for dedicated instructions

This section describes precautions when using dedicated instructions.
Precautions for dedicated instructions (common)
■When changing data specified by dedicated instructions
Do not change any data (such as control data) until execution of the dedicated instruction is completed.
■When the dedicated instruction is not completed
Check whether the mode of the master/local module is online.
A dedicated instruction cannot be executed when the mode is offline or module communication test.
■When using the submaster function
For the precautions when using the submaster function, refer to the following.
Page 171 Programming for when the submaster function is used
■When using the safety program
Dedicated instructions cannot be used in safety programs.
■When using the REMFR, REMTO, REMFRD, REMTOD, SINFTYRD, or SINFSTRD instructions
When using the REMFR, REMTO, REMFRD, REMTOD, SINFTYRD, or SINFSTRD instructions, configure an interlock with
the following module labels.
• 'Data link error status of own station' (SB0049)
• 'Data link status of each station' (SW00B0 to SW00B7) of the target station
Check that the data link status is normal. ('Data link error status of own station' (SB0049) and 'Data link status of each station'
(SW00B0 to SW00B7) of the target station are off.)
Precautions for dedicated instructions (when used in a redundant system)
■System switching during execution of a dedicated instruction
When systems are switched during execution of a dedicated instruction, the dedicated instruction may not be completed.
Execute the dedicated instruction again from the control system CPU module after system switching.
■Specification of the target station CPU type in dedicated instructions
For a dedicated instruction in which the target station CPU type is specified as a control data, the control system CPU,
standby system CPU, system A CPU, and system B CPU can be accessed by specifying the type. ( MELSEC iQ-R
Programming Manual (Instructions, Standard Functions/Function Blocks))
■Processing at abnormal end of a dedicated instruction
When the dedicated instruction is executed by specifying the access destination CPU module, it may be completed with an
error if systems are switched in the target station. If the dedicated instruction was completed with an error, execute it again.
■When a redundant master station configuration is used
Check the programming of when the submaster function is used. ( Page 171 Programming for when the submaster
function is used)
■SEND instruction
• When the target station is in a redundant system, the communication request source station must identify that the target
station is the control system to execute the SEND instruction. When the target station is the standby system, the RECV
instruction is not executed at the target station after data is sent by the SEND instruction, and the target station storage
channel becomes occupied and unable to be used.
• When a redundant system exists in a network where broadcast communications are performed, the RECV instruction is not
executed at the standby system, and the storage channel becomes occupied and unable to be used.
APPX
Appendix 6 Dedicated Instruction
A
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