Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 396)

Publication AG-UM008C-EN-P - February 2005
E-14 Sample Ladder Logic
MicroLogix 1000 Analog DF1 Half-Duplex Slave Report-by-Exception MSG
MicroLogix 1000 Analog DF1 Half-Duplex Slave "Report-By-Exception" MSG Logic
Copy all of the "live" discrete and analog values to be written as a "report-by-exception" MSG to the master into a data compare buffer, which is a contiguous block of words starting in B3:0. This copying occurs
continuously between successful MSG writes. If multiple changes occur after the MSG begins executing, and before the MSG has successfully completed, only the last change will be recorded and sent during
the next MSG execution. Care should be exercised with constantly changing analog data so that the MSG doesn't continously retrigg
er thus negating the efficiencies of a "report-by-exception" scheme. In this
example, MicroLogix I/O values will be sent immediately upon any change of discrete I/O, or every 15 seconds, whichever occurs first.
0000
N7:90
13
MSG
Done
COP
Copy File
Source
#I:0.0
Dest #B3:0
Length 2
COP
Data Compare Buffer
MOV
Move
Source
O:0.0
0<
Dest B3:2
0000000000010010<
MOV
Discrete Outputs
COP
Copy File
Source
#I:0.4
Dest #B3:3
Length 4
COP
Analog Inputs
MOV
Move
Source
O:0.4
0<
Dest B3:7
0000000000000000<
MOV
Analog Output
EN
DN
TON
Timer On Delay
Timer
T4:0
Time Base 1.0
Preset 15<
Accum 0<
TON
Max Delay Before
Retriggering MSG
If 15 seconds have elapsed since the last successful completion of the MSG write, snapshot the current data values for writing to the Master and retrigger the MSG (regardless of whether data values have changed
since the last write).
0001
T4:0
DN
Delay
Timer
COP
Copy File
Source
#B3:0
Dest #N7:0
Length 8
COP
MSG Write Buffer
U
N7:90
15
MSG
Enable
JMP
Q2:2
Jump to
MSG Rung
If the MSG is enabled, skip over the data comparison rungs directly to the MSG rungs. If the MSG has just completed in error, retrigger the MSG immediately, clear the MSG timeout bit if it is set, and jump
directly to the MSG rungs.
0002
N7:90
13
MSG
Done
N7:90
12
MSG
Error
U
N7:90
15
MSG
Enable
N7:90
8
MSG
Timeout
U
N7:90
8
MSG
Timeout
JMP
Q2:2
Jump to
MSG Rung