Power Supply Units
Section 3-4
3-4-4 Emergency Stop
You can use an external relay (CR in the following figure) to form an emergency
stop circuit that shuts down the system when PC operation stops. This can be
achieved by wiring the RUN output from the Power Supply Unit on the CPU Rack
as shown below.
MCB1
Power supply
MCB2
CR1
Control section
Transformer
or noise filter
PC
Twisted-pair wires
+
–
DC voltage
regulator
DC
input/output
PC RUN
output
CR1
Surge suppressor
3-4-5 Power Interruptions
A
sequence circuit is built into the PC to handle power interruptions. This circuit
prevents malfunctions due to momentary power loss or voltage drops. A timing
diagram for the operation of this circuit is shown below.
Power interruption
85%
Power supply
power interruption detection time: 10 to 25 ms*
Power interrup
tion detection
signal
-
Momentary power inter
-
Initialization
Shutdown processing
ruption time (default: 0 ms)
Normal
Normal
Program execution
Power OFF
interrupt program
Power-ON
interrupt program
Stops
Standby
Momentary Power
Interruption Flag
(A40202)
Power retention time: 10 ms (fixed)
CPU reset signal
RUN output
*
0.3 to 1 ms for DC power.
57
OMRON [ OMRON ELECTRONICS LLC ]
