Allen-Bradley MicroLogix 1000 User Manual

Preface
MicroLogix 1000 Programmable Controller User Manual
13–10
 Following the successful receipt of the packet, the Tar get Node sends a reply
packet. The reply packet will contain one of the following responses:
• I have successfully performed your write request.
• I have successfully performed your read request, and here is your data.
• I have not performed your request because of an error.
At the next end of scan, following the Target Node’s reply, the MicroLogix 1000
controller examines the MSG packet from the target device. If the reply
contains “I have successfully performed your write request,” the DN
bit is set
and the ST bit is cleared. The MSG instruction is complete. If the MSG rung is
false, the EN bit is cleared the next time the MSG instruction is scanned.
If the reply contains “I have successfully performed your read request, and here
is your data,” the data is written to the appropriate data table, the DN
bit is set,
and the ST bit is cleared. The MSG instruction function is complete. If the
MSG rung is false, the EN bit is cleared the next time the MSG instruction is
scanned.
If the reply contains “I have not performed your request, because of an error,”
the ER bit is set and the ST bit is cleared. The MSG instruction function is
complete. If the MSG rung is false, the EN bit is cleared the next time the MSG
instruction is scanned.
MSG Instruction Error Codes
Note Any MSG instruction that is in pr ogr ess during a network pr otocol switch will not be
pr ocessed and will be discar ded. For mor e information on network pr otocol
switching, see page 3–17.
When an error condition occurs, the error code is stored in the lower byte of the first
control word assigned to the MSG instruction.
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Allen-Bradley MicroLogix 1000 Specifications

General

Brand	Allen-Bradley
Model	MicroLogix 1000
Category	Controller
Language	English