Chapter7 Programming Cautions; Instructions Restricted In Use For Redundant System - Mitsubishi Q12PRHCPU User Manual

7
PROGRAMMING CAUTIONS

CHAPTER7 PROGRAMMING CAUTIONS

This chapter provides the programming cautions (restrictions on instructions, and fixed-
scan clocks and fixed scan execution type programs).

7.1 Instructions Restricted in Use for Redundant System

Some instructions are restricted in use to a redundant system as indicated below.
(1) Instructions Requiring a Certain Number of Scans
Data-processing
Instructions
Character String
Processing
Other Convenient
Instructions
Instructions Dedicated to Intelligent Function Modules
(a) Instruction Operations
Some instructions require a certain number of scans from start to completion of
the execution. If system switching conditions are satisfied while this kind of
instruction is being executed, the CPU stops the execution and the relevant
processings will not be completed.
In this case, it is necessary to use the user program to execute that instruction
again after system switching.
Table7.1 Instructions Requiring a Certain Number of Scans
Instruction Classification
Sort
Read
Write data to specified file
Read data to specified file
* 1: Refer to the manual of the intelligent function module used, for the instructions dedicated to
intelligent function modules.
7.1 Instructions Restricted in Use for Redundant System
Instruction Execution
Symbol Completion Signal
• SORT
• DSORT
COMRD
SP.FWRITE
SP.FREAD
*1
–
1
2
3
4
Present
5
Present
Present
Present
Present
6
7
8
7
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