Set and Reset Bistables

The Set-Reset and Reset-Set bistables are useful function blocks as they allow an output state to be determined by the states of two inputs. This is especially useful for providing push button functionality, for example, an SR function block can be used to provide the functionality for start and stop buttons—the output of the SR function block is dependent on whether the input is true for the start button, the stop button, or both.

There are 2 Set and Reset bistables:

• RS—The Reset input is dominant in the RS function block.
• SR—The Set input is dominant in the SR function block.