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5.3 The System Switching Function
5.3.5 Special Relays/Registers For System Switching
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5.3.5 Special Relays/Registers For System Switching
(1) Special Relays For System Switching
Special relays for system switching are shown in Table5.38
Set, – Not set
(2) Special Registers For System Switching
Special registers for system switching are shown in Table5.39
Set, – Not set
Table5.38 Special Relays For System Switching
Device
No.
Name
Description
Setting at Time of System Switching
New Control System
CPU Module
New Standby
System CPU Module
SM1590
System switching
enable/disable
flag from network
module
• Turns ON when a system switching request is issued from the network
module. The module No. that issued system switching can be checked by
SD1590.
• Turns OFF when all bits of SD1590 are OFF.
SM1591
Standby system
error detection
disable flag at
system switching
This flag is used to determine if the new standby station detects
6210:STANDBY during system switching.
This applies to the following switching methods:
• System switching from GX Developer
• System switching using dedicated instruction
• System switching by the intelligent function module
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Table5.39 Special Registers For System Switching
Device
No.
Name
Description
Setting at Time of System Switching
New Control System
CPU Module
New Standby
System CPU Module
SD5
Error common
information
Stores the system switching condition that occurred in the control system prior
to system switching only when "5 (System switching condition)" is saved to
error common information category code for SD4.
0: No system switching condition (default)
1: Power OFF, reset, hardware failure, watchdog timer error
2: Stop error (except watchdog timer error)
3: System switching request by network module
16: Control system switching instruction
17: Control system switching request from GX Developer
SD16
Individual error
information
Stores system switching disenabling condition only when "8 (System switching
condition)" is saved to individual error information category code for SD4.
0: Switch successfully completed (default)
1: Tracking cable malfunction (cable disconnection, cable malfunction,
internal circuit malfunction, or hardware malfunction)
2: Hardware failure, power OFF, resetting or watchdog timer error occurring
on standby system
3: Hardware failure, power OFF, resetting or watchdog timer error occurring
on control system
4: Preparing for tracking communication
5: Timeout
6: Stop error (other than watchdog timer error)
7: Operations on the 2 systems are different (detected only in Backup Mode)
8: Copying memory from control system to standby system
9: Writing during RUN
10: Fault detection by standby system network module
11: Executing system switching
12: Online module change
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