Precautions For Dedicated Instructions; Precautions For Dedicated Instructions (Common) - Mitsubishi Electric MELSEC Q Series Reference Manual

9.2

Precautions for Dedicated Instructions

9.2.1

Precautions for dedicated instructions (common)

The following explains precautions for using dedicated instructions.
(1) Change of the data specified with dedicated instructions
Do not change any data (control data, etc.) until execution of the dedicated instruction is completed.
(2) When a dedicated instruction has not been completed
Dedicated instructions must be executed in online.
Execution of the dedicated instructions is not allowed in offline.
(3) Accessing another station with a dedicated instruction during CC IE Control
diagnostics
Execution of the dedicated instruction may not start for a while.
Execute the dedicated instruction by any of the following methods after processing of the CC IE Control
diagnostics.
For safety CPUs, however, the following methods are not available.
(a) Using the COM instruction
Execute the dedicated instruction after executing the COM instruction for communication with the peripheral
(programming tool).
1.
Store 0 in Refresh processing selection when the COM/CCOM instruction is executed (SD778).
2.
Turn ON Selection of refresh processing during COM/CCOM instruction execution (SM775).
3.
Execution of the COM instruction activates communication with the programming tool.
4.
Access another station with a dedicated instruction.
(b) Using the Time reserved for communication processing (SD315) (For Basic model
QCPUs, High Performance model QCPUs, Process CPUs, and Redundant CPUs)
Using the Time reserved for communication processing (SD315), secure a time of 2ms to 3ms for
communication processing.
326
SM402
Start contact
MOV H0 SD778
SET SM775
COM
Dedicated instruction