Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 130)

Chapter 8
Using Basic Instructions
8–11
Using MRD
The MRD instruction reads the rung state stored by the MPS instruction and
resumes operation using that rung state. Each branch structure can have a
maximum of 73 MRD instructions.
This instruction can only be used if all of the following statements are true:
•
An MPS instruction was used previously on the rung.
•
The MRD is immediately preceded by an output instruction.
•
An output circuit immediately follows the MRD.
•
The output circuit that follows the MRD is not the last output circuit in
the rung requiring the rung state stored by the MPS. (If it is the last
output circuit requiring the stored rung state, you must use an MPP
instruction instead of an MRD instruction.)
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 0 M R D
The example below illustrates when you would enter the MRD instruction.
NEW RUNG
LD a

MPS
AND b
OUT c
 MRD
AND d
OUT e
 MPP
AND f
OUT g
Instruction List
a
d e
b c
f g




Using MPP
Like the MRD instruction, the MPP instruction reads the rung state stored by
the MPS instruction and resumes operation using that rung state. Unlike the
MRD instruction, the MPP also clears the rung state from the MPS.
This instruction can only be used if all of the following statements are true:
•
An MPS instruction was used previously on the rung.
•
The MPP is immediately preceded by an output instruction.
•
An output circuit immediately follows the MPP.
•
The output circuit that follows the MPP is the last output circuit in the
rung requiring the rung state stored by the MPS. (If it is not the last
output circuit requiring the stored rung state, you must use an MRD
instruction instead of an MPP instruction.)
1
To enter the function code, press:
FUN ENT
1