BECKHOFF EL6900-FB - Manual (Page 23)

Function blocks
Function blocks for TwinSAFE logic terminals 21
3.2 The OR function block
3.2.1 Functional description
With the FB OR several input signals can be linked via OR to one output signal. In addition each input
can still be set even if the input signal is a normally closed contact (Break contact) or normally open
contact (Make contact). A normally open contact means that the corresponding input signal is negated,
before it affects the OR.
Figure 3-3: OR function block