Publication 1763-RM001C-EN-P - October 2009
548
Knowledgebase Quick Starts
Problem #3:
Some of my outputs will not turn On or Off when the
ladder logic appears to indicate that they should.
Solution:OMB (Output Mask Bits).
Verify what the OMB has been
configured for in the HSC function file. If an output(s) has been assigned
to the HSC for control, then the output(s) will not be controlled anywhere
else in the ladder program. Only the HSC will have control over these
outputs.
# 17465 “Quick Start”
Message (MSG)
Communications Specifications:
The MicroLogix 1100 processors contain a total of (12) Message Buffers.
The Outgoing queue also supports unlimited queuing. This means that
even if a buffer is not available the MSG will simply wait until one of the
outgoing buffers becomes available and then transmit.
NOTE:If a message has been waiting in the queue, at the moment of
buffer availability, the most current data will be sent, not the data that was
available at the time the message instruction was first scanned true.
How quickly a message is actually sent or received to/by a destination
device depends on a number of issues, including the selected channels
communication protocol, baud rate of the communications port, number
of retries, destination devices readiness to receive, ladder logic scan time,
etc.
Definition of the Message (MSG) instruction:
The message instruction (MSG) is an output instruction which when
configured correctly allows data to be sent or received to other
compatible devices.
The MSG instruction in the MicroLogix 1100 controller uses a Data File
MG to process the message instruction. All message elements are accessed
using the MG prefix (example: MSG done bit = MG11:0/DN).
(8) Incoming
Any incoming MSG's, Communications, and/or
responses to a command the ML1100 initiated.
(4) Outgoing
Any outgoing MSG's, Communications and/or
responses to incoming request for data.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
