Retentive timer `RTO`

Like TON, but keeps ACC when the rung goes false. Clear it with RES.

Global.PumpHours

PRE 60000 ACC 600 EN 1 TT 1 DN 0

Tag	After two scans
PumpHours	PRE 60000 ACC 600 EN 1 TT 1 DN 0

How it works

Times while the rung is true. DN sets when ACC reaches PRE. ACC and DN keep their values when the rung goes false, until a RES clears them.

Use RTO to add up time across several runs, such as total heating time.

Global.Heating

Global.HeatTime

PRE 60000 ACC 600 EN 0 TT 0 DN 0

Global.ResetPB

Global.HeatTime

Heating turned off. HeatTime kept its ACC.

Operand	Data type	Read or write
Timer	TIMER	Reads and writes

Member	Type	Meaning
.PRE	DINT	Preset: the time to reach, in ms
.ACC	DINT	Accumulated: the time so far, in ms
.EN	BOOL	On while the rung is true
.TT	BOOL	On while the timer is timing
.DN	BOOL	Done: on when ACC reaches PRE

No way to clear itAn RTO keeps ACC and DN until a RES on the same TIMER tag clears them.
Using one TIMER tag in two timersEach timer writes ACC, TT and DN, so the first one in the scan changes them before the next one runs. Problems shows this as written by 2 timers. Give each timer its own tag, unless you want that order.