PLC shift register ladder diagram instruction

Just like a shift register in digital electronics, the PLC shift register contains a number of register. Each register is 16-bit wise. The content of each register shifts from one stage to next stage, for example reg[2]=reg[1] and reg[1]=reg[0].

Shift Register Instruction Symbol

We must name the register and its stage.

Instruction Property

Stages define the number of the 16-bit shift register in used.

In this example, I use a UART terminal of a host PC to send the character to the PLC and echo the character back.

Ladder Diagram Example

Schematic Diagram

Click here to download this ladder diagram example.