Rockwell Automation 1760-xxxx Pico Controller User Manual - Manual (Page 154)

Publication 1760-UM001D-EN-P - September 2005
7-4 Retention
Change the Start-Up Behavior in the SYSTEM Menu
The retentive actual values in Pico are retained irrespective of the
MODE RUN or MODE STOP settings.
Retentive Auxiliary Relays
(Markers) How the Retention Works
The retentive markers M13, M14, M15, M16, D1 to D8 should be used
in conjunction with the following coil functions.
.
It is essential that you note the following points:
• When retention is used, the open or closed status of a retentive
marker is remembered when power is disconnected. When
power is restored, the marker assumes the same state, even if
the conditions that would have changed its state occurred while
the power was disconnected. If the conditions have changed,
the state of the marker will reflect the change following the first
program cycle after power is restored. This may result in the
flicker or chatter of a lamp, solenoid, or quick responding load.
• Retention is useful for remembering that an event has occurred,
like a latch or flip-flop. On the other hand, a conventional relay
responds continuously to the electrical conditions at its coil. For
this reason, the output energize function (i.e. {M13) is not
recommended in combination with the retentive markers M13 to
M16 and D1 to D8.
• Because of retention, the following coil functions are not
recommended: {M13 to {M16 and {D1 to{D8
• Be sure to pay close attention to the example circuits for the
individual coil functions.
Instruction Type Representation in Pico
Set S M…, D…
Impulse Relay M…, D…
Reset R M…, D…
TIP
When the condition for resetting the marker is
satisfied, the marker is reset.