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APPX
Appendix 4 List of Special Relay Areas
SM152 Momentary power failure
detection (power supply
module 1)
Off: Not detected
On: Detected
• This relay turns on when a momentary power failure of the
input power supply to the power supply 1 or 2 is detected
one or more times. After turning on, this relay remains on
even if the power supply recovers from the momentary
power failure.
• This register monitors the status of the power supply
module mounted on the main base unit and counts the
number of momentary power failures.
• This relay turns off the flags (SM152 and SM153) of the
power supply 1 and 2 when the CPU module starts up.
• When one of the two power supply modules is powered off,
this relay turns off the corresponding flag to one powered
off.
• In a multiple CPU system, the flags are stored only to the
CPU No.1.
S (Status change)
SM153 Momentary power failure
detection (power supply
module 2)
S (Status change)
SM154 Invalid power supply
module
Off: Valid/power-off/no power
supply module
On: Invalid
• This relay turns on when one or more invalid power supply
modules is detected on the redundant power supply base
unit or a redundant extension base unit.
• This relay turns on if a factor to turn on any bits of SD154
have been occurred.
• This relay turns off if all the factors to turn on any bits of
SD154 have been removed.
• In a multiple CPU system, the flags are stored only to the
CPU No.1.
• In a redundant system with redundant extension base unit,
if an invalid power supply module is detected on an
extension base unit, the on/off state is stored only in the
CPU module of the control system, but not stored in the
CPU module of the standby system.
S (Status change)
No. Name Data stored Details Set by (setting
timing)
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