RE: how to trigger on positive edge only with snl

["Allison, Stephanie" <saa@slac.stanford.edu>]

Hi,

If it is simple, you could do something in record processing like this:

record(bo, "a_binary_PV") {
  field(OUT, "a_sequence_PV.SELN PP")
  field(ZNAM, "no_change")
  field(ONAM, "change")
}
record(seq, "a_sequence_PV") {
  field(SELM, "Specified")
  field(DOL1, "an_action_PV_value")
  field(LNK1, "an_action_PV PP")
}

But now "a_sequence_PV" is in the same lockset as the "a_binary_PV" which may not be acceptable.

Stephanie Allison

> -----Original Message-----
> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf
> Of Song Hu
> Sent: Thursday, March 21, 2013 8:58 AM
> To: tech-talk@aps.anl.gov
> Subject: how to trigger on positive edge only with snl
> 
> Hi,
> 
> I would like to trigger some actions when a binary PV changes from 0 to 1. No action
> should be taken when it changes from 1 to 0. I made some code like:
> 
> int bin;                  assign bin to "abc:bin";                                    monitor bin;
>                                 evflag  binFlag;                                                    sync  bin   binFlag;
> ss ttt
> {
>   state testState
>   {
>      when(efTestAndClear(binFlag)&&(bin == 1))
>      {
>            printf("Received a trigger!!\n");
>      }state testState
>   }
> }
> 
> When abc:bin changes from 0 to 1 and then quickly go back to 0, it is not working every
> time.
> 
> What is the appropriate way to implement such positive edge only trigger?
> 
> Thanks in advance for your help.
> 
> Song