BECKHOFF EL6900-FB - Manual (Page 14)

System description
12 Function blocks for TwinSAFE logic terminals
Figure 2-1: Inputs/Outputs
Table 2-3: Status information
Value Status Description
1 RUN All function blocks and TwinSAFE connections assigned to the TwinSAFE
group operate properly, and all TwinSAFE connections assigned to the
TwinSAFE group are up and running
2 STOP State after initialization
3 SAFE All function blocks and TwinSAFE connections assigned to the TwinSAFE
group operate properly, and at least one of the TwinSAFE connections
assigned to the TwinSAFE group is not yet up and running
4 ERROR At least one assigned function block or one assigned TwinSAFE connection
has reported an error
5 RESET A positive edge (FALSE->TRUE) for acknowledgement of a function block
or a TwinSAFE connection error was detected on the ERR_ACK input. The
system is waiting for the negative edge of the ERR_ACK input