Experimental Physics and
Industrial Control System

Try this:

record(seq, "$(P)arm") {
    field(DO1, "1")
    field(LNK1, "$(P)state.D PP NMS")
    field(DO2, "0")
    field(LNK2, "$(P)state.D PP NMS")
    field(DO3, "0")
    field(LNK3, "$(P)state.A NPP NMS")
    field(DESC, "process to arm timer")
}

record(bi, "$(P)bi") {
    field(FLNK, "$(P)state.PROC")
    field(DESC, "record whose values are timed")
}

record(calcout, "$(P)state") {
    field(INPB, "$(P)bi NPP")
    field(CALC, "c:=(a==0)?b:c;a:=(b==c?a+1:a);a==1?1:a==2?0:-1")
    field(OUT, "$(P)counter.A NPP")
    field(DESC, "counter state")
}

record(calcout, "$(P)counter") {
    field(INPB, "$(P)counter.VAL NPP")
    field(INPC, "$(P)counter.D NPP")
    field(CALC, "a==-1?0:(a?b+1:b)")
    field(SCAN, ".1 second")
    field(DESC, "counter")
}

To arm the counter, process $(P)arm.  Once armed, the next time $(P)bi is processed, the counter will start, and the value that started it will be recorded.  The next time $(P)bi processes and has the recorded value, the counter will stop.

Tim Mooney