Preface
MicroLogix 1000 Programmable Controller User Manual
13–10
Following the successful receipt of the packet, the Target 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 progress during a network protocol switch will not be
processed and will be discarded. For more information on network protocol
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.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
