Chapter 9—C445 Logic Engine and Expansion I/OPower Xpert C445 Global Motor Management Relay MN042003EN—January 2019 www.eaton.com 187RTOF—Retentive Off-Delay TimerThe RTOF function block is a retentive off-delay timer that delays a TRUE to FALSEtransition of IN to OUT by a time defined by PT. Once the timer reaches the PT, the timerstops running and sets the OUT to FALSE. This behavior is the same as that of the TOFfunction block, but compared to TOF, the RTOF function block can retain the state of thetimer when IN transitions from FALSE to TRUE before the timer could complete (ET = PT),essentially “pausing” the timer. When the IN transitions back to FALSE while the timer isin the paused state, the timer resumes from its retained state instead of starting fromzero. The timer can be reset by providing a rising edge trigger to the RESET input. Inaddition to being retentive, the timer is also persistent through power cycle, meaning thatthe timer will retain its state in the event of a power loss to the device.Parameter Data type DescriptionIN BOOL Input trigger to start timer—falling edgePT UINT Preset time (x1ms, x10ms, 100ms, x1s)RESET BOOL Reset timer—rising edgeOUT BOOL Timer expired flag—active lowET UINT Elapsed time (x1ms, x10ms, 100ms, x1s)Power Loss
