DL06 Micro PLC User Manual, 3rd Edition, Rev. E
5-181
Chapter 5: Standard RLL Instructions
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Understanding Master Control Relays
The Master Line Set (MLS) and Master Line Reset (MLR) instructions allow you to quickly
enable (or disable) sections of the RLL program. This provides program control flexibility. The
following example shows how the MLS and MLR instructions operate by creating a sub power
rail for control logic.
K aaa
MLS
K aaa
MLR
X0
X1
X2
OUT
Y7
X3
MLS
X10
K1
K2
K0
K1
MLS
OUT
MLR
MLR
OUT
Y10
Y11
Direct SOFT32
When contact X0 is ON, logic under the first MLS
will be executed.
When contact X0 and X2 are ON, logic under the
second MLS will be executed.
The MLR instructions note the end of the Master
Control area.
Operand Data Type
DL06 Range
aaa
Constant K
1-FFFF
Operand Data Type
DL06 Range
aaa
Constant K
1-FFFF
DS
Used
HPP Used
DS
Used
HPP Used
Direct
SOFT
Master Line Set (MLS)
The Master Line Set instruction allows the program to control sections
of ladder logic by forming a new power rail controlled by the main left
power rail. The main left rail is always master line 0. When an MLS K1
instruction is used, a new power rail is created at level 1. Master Line Sets
and Master Line Resets can be used to nest power rails up to seven levels
deep.
Master Line Reset (MLR)
The Master Line Reset instruction marks the end of control for the
corresponding MLS instruction. The MLR reference is one less than the
corresponding MLS.