Automating Manufacturing Systems - Process Control and ...

plc function ref - 34.35
MSG - MeSsaGe
A
MSG
SEND/RECEIVE MESSAGE
Control Block MG9:0
Description:
This is a multipurpose instruction that deals with communications in general.
The instruction is controlled by the contents of the control block,
which is normally set up using the programming software. The
instruction can send and receive data across most interfaces including
DH, DH+, Ethernet, RS-232, RS-422 and RS-485. The message
blocks ’MG’ are preferred for storing the configuration, but integer
memory may also be used. The messages are segments of PLC memory.
These can be read from, or written to a remote destination.
Status Bits:
EN
ST
DN
ER
CO
EW
NR
TO
enable - indicates when the instruction is active
start -
done - indicates when the instruction is complete
error - an error occurred
continuous - when set the instruction doesn’t need a true input
enabled waiting -
no response - the remote destination was not detected
time out - the remote destination did not respond in time
Registers: many refer to manuals
Available on: Micrologix, PLC-5
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