5
REDUNDANT SYSTEM FUNCTIONS
5.1 Basic Concept of Redundant System
5.1.4 System Consistency Check
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(1) File Consistency Check
(a) Check points
The file consistency check means checking the following files at system switching
as shown in Table5.11.
* 1 If the memory capacities of the area for online change of multiple blocks are different in both
systems, carry out the following operations:
•Using memory copy from control system to standby system function, copy the program memory
contents of the control system to the standby system.
•Format program memories of both system CPU modules. (The memory capacities of the area
for online change of multiple blocks will be the same.)
(b) Inconsistency Errors
Table5.12 shows the file inconsistency errors occurred when the target files are
inconsistent.
If the "FILE DIFF." occurs in the standby system, execute the PLC verify by either
of the methods described below to confirm the differences between the files of
both system, correct the problem file, and perform write to PLC again.
• After reading the system A programs and parameters using GX Developer or
PX Developer, compare them with the System B programs and parameters.
• Verify the GX Developer and PX Developer programs and parameters saved
in the offline environment with the those written to both system CPU modules.
* 2 If a stop error occurs in the standby CPU module, the "STANDBY SYS. DOWN (error code:
6300)" continuation error will occur in the control system CPU module.
Table5.11 Target Files and Check Contents
Target Files
Details
Parameters
• Checks the parameters stored in the drive set as parameter valid drive
(PLC parameters, redundant parameters, network parameters) and
the intelligent function module parameters set with GX Configurator.
• Checks the remote password stored in the program memory.
Programs
• Checks the program file set in the PLC parameters program settings.
• The password set in the password registration is irrelevant.
Initial Device Values
• Checks the initial device value file set in the PLC parameter PLC file
settings.
• The password set in the password registration is irrelevant.
Area for Online Change of
Multiple-Block Write
• Checks the memory capacity of the area for online change of multiple
blocks set during formatting.
*1
Table5.12 File Inconsistency Errors
Execution Conditions
Error Description
• When both systems are powered ON
simultaneously.
• When both system CPU modules are unreset
(RESET/L.CLR switch is set to the neutral
position) simultaneously.
• When one system starts up after the other.
• When the separate mode is changed to the
backup mode.
The following stop error will occur only in the
standby system CPU module only: "FILE DIFF.
(error code: 6000)".
*2