We already discussed Timers, counters and other instructions used in PLC programming. Sometimes we may need some operations in the PLC programs which involve blocks of data operations. The instructions like timers and counters handle single bit of data, either 1 or 0.
The data handling instructions deals with more than a bit, like moving or transferring numbers from one memory location to another, comparing data values or performs simple arithmetic operations.
Move (MOV) Instructions
This output instruction moves the source value to the destination location. As long as the rung remains true, the instruction moves the data on each scan.
Entering Parameters
Source is the address or constant of the data you want to move.
Destination is the address where the instruction moves the data.
Application Note: If you wish to move one word of data without affecting the math flags, use a copy (COP) instruction with a length of 1 word instead of the MOV instruction.
Using MOV for Variable Initialization
S:1/15 is a bit in the status date file that is energized for exactly one PLC scan when the PLC is placed in run mode.
It Can be used to condition the initialization of variables used elsewhere in the ladder logic.
Masked Move (MVM) Instruction
The MVM instruction is a word instruction that moves data from a source location to a destination and allows portions of the destination data to be masked by a separate word.
- S:0/0, carry (C)
- S:0/1, overflow (V)
- S:0/3, sign (S)
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