Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 182)

Report Generation
Chapter 9
9Ć14
Figure 9.5
Message Request BitĆDone Bit Relationship
17 10 07 00
Message Request Bits Message Done Bits
Message
Control
Word
The message print command is valid for message 0. It will print out the
message control word addresses such as tabular form shown in Table 9.B.
If the location of the message control file is to be changed or if message 0
is no longer needed, it can be deleted with the message delete command
and re-entered at any time.
WARNING: Message control words should not be used for any
other purpose. Message control words also must not be used
in output image table locations when output or block transfer
modules are placed in corresponding slots. Hazardous or
unexpected machine operation could result. Damage to
equipment and/or personal injury could result.
Using latch and unlatch instructions, automatic report generation can easily
be programmed to handle multiple or simultaneous message requests.
Simultaneous requests are handled by a priority system – the lower the
message number, the higher the priority.
Figure 9.6 shows a sample program that can be used to activate each
message. When the event occurs which requests the message, the request
bit is latched. After the event has occurred and the message is printed
(the done bit comes on), the request bit is unlatched. This technique also
ensures the requested message only gets printed one time per request.
9.3.3
Example Programming