GE Industrial Solutions Entellisys 5.0 Integrator's Guide - Manual (Page 21)

Interfacing to the Alarm Handler 21
Figure 1-9 Fault has cleared but acknowledge Persists
PLC Implementation
The alarm status is updated and cleared quickly (within 50ms), so a Modbus client will not be
able to detect the trip alarm with any reliability. Therefore, for most relays, 3rd party Modbus
clients should read the Acknowledge registers. When an event has occurred and the Modbus
client has consumed the information, the Modbus client could then take a some action that
would ensure that the Acknowledgement bit is cleared before the breaker is re-closed. The of
most straight forward of which would be for the client to clear though a write command.