Shift register (0BA7 to 0BA8)

Short description

The shift register function reads an input value and shifts the bits. The output value corresponds with the configured shift register bit. The shift direction can be changed at a special input.

For LOGO! 0BA6, you can use only one shift register in one circuit program, but for LOGO! 0BA7 and LOGO! 0BA8 devices, you can use a maximum of four shift registers with eight bits for each shift register in one circuit program.

Connection

Description

Input In

The function when started reads this input value.

Input Trg

The SFB is started with a positive edge (0 to 1 transition) at input Trg (Trigger). A 1 to 0 transition is irrelevant.

Input Dir

You define the shift direction of the shift register bits Sx.1 to Sx.8 at the Dir input:

Dir = 0: shift up (Sx.1 >> Sx.8)
Dir = 1: shift down (Sx.8 >> Sx.1)

NOTE:

"x" refers to the index of the shift register.

Parameter

Shift register index: the index of shift register in the circuit program.

Possible settings: 1 to 4

Shift register bit that determines the value of output Q.
Possible settings: 1 to 8

Retentivity set (on) = the status is retentive in memory.

Output Q

The output value corresponds with the configured shift register bit.

Parameter

LOGO! 0BA7 or 0BA8 devices provide four shift registers, with eight bits for each shift register. The shift register index corresponds to one of the four shift registers in the circuit program. The shift register bits are numbered in Sx.y, in which x is the index, and y is the bit number.

Timing diagram

If the shift register index is 1, the shift register bits will be S1.1 to S1.8.

Description of the function

The function reads the value of input In with a positive edge (0 to 1 transition) at input Trg (Trigger).

This value is written to shift register bits Sx.1 to Sx.8, depending on the set shift direction:

Q outputs the value of the configured shift register bits.

If retentivity is not enabled, the shift function restarts at Sx.1 or Sx.8 after a power failure.

Overview