7
PROGRAMMING CAUTIONS
7.1 Instructions Restricted in Use for Redundant System
7 - 1
1
OVERVIEW
2
SYSTEM
CONFIGURATION
3
TRACKING CABLE
4
PROCEDURE FOR
STARTING UP A
REDUNDANT SYSTEM
5
REDUNDANT SYSTEM
FUNCTIONS
6
REDUNDANT SYSTEM
NETWORKS
7
PROGRAMMING
CAUTIONS
8
TROUBLESHOOTING
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
(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.
* 1: Refer to the manual of the intelligent function module used, for the instructions dedicated to
intelligent function modules.
Table7.1 Instructions Requiring a Certain Number of Scans
Instruction Classification
Instruction
Symbol
Execution
Completion Signal
Data-processing
Instructions
Sort
•SORT
•DSORT
Present
Character String
Processing
Read COMRD Present
Other Convenient
Instructions
Write data to specified file SP.FWRITE Present
Read data to specified file SP.FREAD Present
Instructions Dedicated to Intelligent Function Modules
*1
–Present
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