Allen-Bradley MicroLogix 1100 Instruction Set Reference Manual

Publication 1763-RM001B-EN-P - April 2007
346 Communications Instructions
You can place this rung after a message write instruction. CS0:4/MCP is set
when the message instruction is enabled and put in the communications
queue. When CS0:4/MCP is set (1), the SVC instruction is evaluated as true
and the program scan is interrupted to execute the service
communication’s portion of the operating scan. The scan then resumes at
the instruction following the SVC instruction.
The example rung shows a conditional SVC, which is processed only
when an outgoing message is in the communications queue.
MSG - Message
Instruction Type: output
Any preceding logic on the message rung must be solved true before the
message instruction can be processed. The example below shows a
message instruction.
If B3:0 is on (1), the MSG rung is true, and MG11:0 is not already
processing a message; then MG11:0 is processed. If one of the four
buffers is available, the message and its associated data are processed
immediately.
TIP
You may program the SVC instruction unconditionally
across the rungs. This is the normal programming
technique for the SVC instruction.
EN
DN
ER
MSG
Read/Write Message
MSG File MG9:0
Setup Screen
MSG
Execution Time for the MSG Instruction
Controller Rung Condition When Rung Is:
True False
MicroLogix
1100
Steady State True 10.14 μs 5.62 μs
False-to-True Transition for Reads 59.58 μs 5.62 μs
False-to-True Transition for Writes 68.26 μs 5.66 μs
0
B3:0
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Allen-Bradley MicroLogix 1100 Specifications

General

Brand	Allen-Bradley
Model	MicroLogix 1100
Category	Controller
Language	English