Middle String (MID)

The MID instruction copies a specified number of ASCII characters from a string and stores them in another string.
The MID instruction copies a group of characters from the Source and places the result in the Destination.
  • The Start position and Quantity define the characters to copy.
  • Unless the Source and the Destination are the same tag, the Source remains unchanged.
Available Languages
Ladder Diagram
Ladder Diagram_Middle String (MID)_v1
FactoryTalk Design Studio
 DSL - Ladder Diagram
MID(Source,Qty,Start,Dest);
Operands
There are data conversion rules for mixed data types within an instruction. See Data Conversion.
Ladder Diagram
Operand
Type
Format
Description
Notes
Source
ANY_STRING
Tag
The string to copy characters from
String types are:
  • Default STRING data type with max 82 length of characters for the string.
  • Any new string type you created with configurable length of characters for the string.
Quantity
SINT
INT
DINT
Immediate
tag
The number of characters to copy
The Start plus the Quantity must be less than or equal to the length size of the Source plus 1.
Start
SINT
INT
DINT
Immediate
tag
The position of the first character to copy
Enter a number between 1 and the DATA size of the Source.
Destination
ANY_STRING
Tag
The string to copy the characters to
Affects Math Status Flags
No
Major/Minor Faults
A minor fault will occur if:
Fault Type
Fault Code
The LEN value of the Source string tag is greater than the DATA size of the Source string tag.
4
51
The length of output string is larger than the DATA size of the destination string tag.
4
52
The Start or Quantity value is invalid.
4
56
Execution
Ladder Diagram
Condition
Ladder Diagram Action
Prescan
N/A
Rung-condition-in is false
N/A
Rung-condition-in is true
The instruction executes.
Postscan
N/A
Example
In the baggage handling conveyor of an airport, each bag gets a bar code. Characters 9 through 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 on), the MID instruction copies the flight number and destination airport to the bag_flt_and_dest string. Subsequent rungs use bag_flt_and_dest to determine where to route the bag.
Ladder Diagram
FTStudio-MID-LD-EX-V1
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