Allen-Bradley PLC-2/30

Output Override and I/O Update Instructions
Chapter 7
72
Figure 7.1
MCR
and ZCL Zone Programming
|| ( ZCL )
|| ( )
||
| / |
| / | ( )
||
||
( )
||
||
||
||
||
( ZCL )
||
( )
( )
| / |
|| ( MCR )
|| ( )
||
| / |
| / | ( )
||
||
( )
||
||
||
||
||
( MCR )
||
( )
( )
| / |
Start Fence
Unconditional End Fence
Start Fence
Unconditional End Fence
When ZCL zone is false
all outputs remain in
their last state.
When MCR zone is false
nonretentive outputs are
deenergized.
The MCR and ZCL instructions control the zoned outputs differently:
MCR — When false, all nonretentive outputs within the MCR zone are
de-energized or turned off.
ZCL — When false, the outputs within the ZCL zone are left in their
last state: either on or off.
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