Used for First Out tripping and alarming. Inputs are set are set high to cause trip/alarm.
The FO16On module monitors 16 discrete inputs. When any of the inputs is set to a high state (i.e. one) the FOLatch output is set to zero, and the FO output value is set to a numeric value corresponding to the input channel of the module that was set high first. The FOLatch output can be used as the interlock for motor and valve blocks. The FO output can be used by an HMI graphic to indicate the initiating cause of the trip. The amount of the HMI screen space needed to indicate the trip cause is minimized, which is useful for smaller HMI screens (e.g.PV600).
Only one alarm output channel is set, corresponding with the channel which triggered the trip. This functionality when combined with the alarming system (e.g. alarm digital blocks) could be used to indicate only the alarm that triggered the trip. This would prevent issues with alarm flooding that occurs during trip conditions.
For applications requiring more than 16 shutdown caused, multiple FO16On modules can be linked together.
PLC Code written in RSLogix 20.04
Used for latch an output ON when the corresponding input to the module goes ON.
Used for latch an output OFF when the corresponding input to the module goes OFF.
When the module is enabled the state of the 16 discrete inputs is copied to the outputs.