Relay Ladder; Structured Text - Allen-Bradley Logix5000 Reference Manual

Execution:
Condition
Prescan
Rung-condition-in is false
Rung-condition-in is true
EnableIn is set
Instruction execution
Postscan
bag_read.EM
Relay Ladder Action
The rung-condition-out is set to false.
The rung-condition-out is set to false.
The instruction executes.
The rung-condition-out is set to true.
N/A
The instruction copies the specified characters from a string and stores them in another string.
The rung-condition-out is set to false.
Example:
In a baggage handling conveyor of an airport, each bag gets a bar code. Characters 9...17
of the bar code are the flight number and destination airport of the bag. After the bar
code is read (bag_read.EM is set) the MID instruction copies the flight number and
destination airport to the bag_flt_and_dest string.

Relay Ladder

Structured Text

IF bag_read.EM THEN
MID(bar_barcode,9,9,bag_flt_and_dest);
bag_read.EM := 0;
END_IF;
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
ASCII String Instructions (CONCAT, DELETE, FIND, INSERT, MID)
Structured Text Action
No action taken.
N/A
N/A
EnableIn is always set.
The instruction executes.
No action taken.
MID
Middle String
Source bag_barcode
'NWA HOP 5058 AMS 01'
Qty 9
Start 9
Dest bag_flt_and_dest
'5058 AMS '
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