Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 155)

Publication 1760-UM001D-EN-P - September 2005
Retention 7-5
Examples
S/R Coil (Break Contact)
Task:
In your application you need to remember whether a screw was
inserted or not. When your machine powers up, it is important that a
screw that has already been screwed in place is not screwed in again -
otherwise there could be permanent damage to the workpiece.
Contacts and relays used:
Circuit diagram (part):
Signal diagram:
The ’Make Contact’ state is always displayed in the Signal diagram.
U = Supply voltage
The break contact of the retentive marker M14 is used. No enabling
time is required for output Q2.
Coil Function
I3 Screw detected
Q2 Enable pulse to drive screw
M8 Enable screw command
M14 Screw present (retentive)
M9 Workpiece transported away, reset M14
M8-M14------{Q2
I3------SM14
M9---------RM14
U
M8
Q2
I3
M9
M14