Installation; Fail-Safe Circuits - Omron NSJ CONTROLLERS - 03-2008 Operation Manual

Installation

5-1

Installation

5-1-1

Fail-safe Circuits

Supply Power to the
NSJ Controller before
the Control System
Managing NSJ
Controller Errors
Managing Output Unit
Malfunctions
90
This section describes installing the NSJ Controller in a control panel, wiring
the power supply, wiring the built-in DeviceNet Section, and mounting/wiring
Expansion Units.
Be sure to set up safety circuits outside of the Controller Section to prevent
dangerous conditions in the event of errors in the NSJ Controller or external
power supply. Pay particular attention to the following items.
If the NSJ Controller's power supply is turned ON after the controlled system's
power supply, outputs in Units such as DC Output Units may malfunction
momentarily. To prevent any malfunction, add an external circuit that prevents
the power supply to the controlled system from going ON before the power
supply to the NSJ Controller itself.
When any of the following errors occurs, NSJ Controller operation will stop
and all outputs from Output Units will be turned OFF.
• Operation of the Power Supply Unit's overcurrent protection circuit
• A CPU error (watchdog timer error) or CPU on standby
• A fatal error* (memory error, I/O bus error, duplicate number error, too
many I/O points error, program error, cycle time too long error, or
FALS(007) error)
Be sure to add any circuits necessary outside of the NSJ Controller to ensure
the safety of the system in the event of an error that stops NSJ Controller
operation.
Note *When a fatal error occurs, all outputs from Output Units will be turned OFF
even if the IOM Hold Bit has been turned ON to protect the contents of I/O
memory. (When the IOM Hold Bit is ON, the outputs will retain their previous
status after the Controller Section has been switched from RUN/MONITOR
mode to PROGRAM mode.)
It is possible for an output to remain ON due to a malfunction in the internal
circuitry of the Output Unit, such as a relay or transistor malfunction. Be sure
to add any circuits necessary outside of the NSJ Controller to ensure the
safety of the system in the event that an output fails to go OFF.
Section 5-1