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<== Date ==> <== Thread ==>

Subject: Re: state notation code flags
From: Patrick Thomas <thomas_p@ligo-wa.caltech.edu>
To: Mark Rivers <rivers@cars.uchicago.edu>
Cc: tech-talk@aps.anl.gov
Date: Sat, 03 Oct 2009 09:15:21 -0700
Hi Mark,

I'm not sure I can ignore certain values. I have an initiation state at the beginning of the program that sets a bunch of values. When it does that I want it to show those values in the requested fields on the medm screen. So there are three records, request, set, and read. The user enters a requested value into the request record, the state notation program sees that change and schedules writing that value to the set record, and then processes the read record to ensure that it was set. But when the state notation program writes the initial value to the request field itself, I don't want it to set the flag, because then it would process again when it looks for changes corresponding to actual user inputs.

I also have it set up that the user can either request a laser power or an angle setting. When they request a laser power it calculates an angle setting and then should write that to the request angle setting field and vice versa. But I don't want that to cause it to process the states for both setting a laser power and setting an angle, only the states for the one the user actually chose.

Thank you,
Patrick

Mark Rivers wrote:
Hi Patrick,
What is it you are trying to do? You are doing both pvPuts and looking for external changes to the same PV? If so, then one solution is to ignore events which correspond to the value that your SNL program set with pvPut, and only act on events with values that must have been done by some external agent. Here is an example from one of my programs:
int     abort;       assign abort        to "{P}{R}Abort.VAL";
monitor abort;
evflag abortMon;        sync abort      abortMon;
...
ss xpsTrajectoryAbort {
    state monitorAbort {
        when ((efTestAndClear(abortMon)) && (abort==1) &&
              (execState==EXECUTE_STATE_EXECUTING)) {
...
            abort=0;
            pvPut(abort);
        } state monitorAbort
    }
}
In this case abort can be set to 1 by the user from outside the SNL program.  If that happens then the SNL program takes some appropriate action, and does a pvPut of abort back to 0.  That would cause another event to be received, but I ignore that event in the when clause()
        when ((efTestAndClear(abortMon)) && (abort==1) &&
              (execState==EXECUTE_STATE_EXECUTING)) {
This will always clear event flags on the abort PV, but will only do the logic inside the when if abort is 1 and execState is EXECUTE_STATE_EXECUTING.
Mark
________________________________

From: Patrick Thomas [mailto:thomas_p@ligo-wa.caltech.edu]
Sent: Sat 10/3/2009 12:37 AM
To: Mark Rivers
Cc: jemian@anl.gov; tech-talk@aps.anl.gov
Subject: Re: state notation code flags



I see, thank you. So is there a way around this, that is to make sure
the monitors are received and the flag is set before the call to efClear
is made, or some way to make a particular pvPut not have channel access
send out monitors for that record?

Mark Rivers wrote:
I think I have figured it out, the following code shows it the most
clearly. Adding SYNC to the pvPut command does not seem to ensure that
it will finish before the next command is processed:
The pvPut command did "finish" before the efClear command was executed.  That means that it wrote its value to the record, and processed that record and any records that process as a result of processing that record.   That record told channel access to send out monitors on that PV to all clients, including your SNL program.  It does NOT wait for those monitors to be received; it simply requests channel access to send them, which is then done asynchronously.  So the event flag in your SNL program will be set some time after you do the pvPut.  What you are observing is the expected and documented behavior of EPICS.

Mark




________________________________

From: Patrick Thomas [mailto:thomas_p@ligo-wa.caltech.edu]
Sent: Fri 10/2/2009 7:03 PM
To: jemian@anl.gov
Cc: Mark Rivers; tech-talk@aps.anl.gov
Subject: Re: state notation code flags



I think I have figured it out, the following code shows it the most
clearly. Adding SYNC to the pvPut command does not seem to ensure that
it will finish before the next command is processed:

program sncTest

float request_maximum_velocity;
assign request_maximum_velocity to "H3:TEST";
monitor request_maximum_velocity;
evflag request_maximum_velocityEvent;
sync request_maximum_velocity request_maximum_velocityEvent;


ss ss1 {
        state init {
                when () {
                        efClear(request_maximum_velocityEvent);

                        request_maximum_velocity = 40;
                        pvPut(request_maximum_velocity, SYNC);
                        efClear(request_maximum_velocityEvent);
                } state wait
        }

        state wait {
                when () {
                        if (efTest(request_maximum_velocityEvent)) {
                                printf("flag set\n");
                        }
                } state wait
        }
}



Pete R. Jemian wrote:
sounds a bit off ... show the code

Patrick Thomas wrote:
I think I have it narrowed down. It appears that when I set variable1
equal to variable2 and variable2 has a flag synced to it (variable1
does not), and then do a pvPut on variable1, sometimes the flag is
set on variable2 and sometimes it isn't. Am I correct? Why does this
occur?

Thank you,
Patrick

Mark Rivers wrote:
Patrick,

Event flags can be explicitly set, which is typically used to allow
communication between state sets.  Or event flags can be synced to a
PV,
and will be set whenever a monitor is received for that PV, as in the
example I sent you.

You can use the efTest() function outside of a when statement, just
like
any other function.

Mark


-----Original Message-----
From: Patrick Thomas [mailto:thomas_p@ligo-wa.caltech.edu] Sent:
Thursday, October 01, 2009 5:20 PM
To: Mark Rivers
Cc: tech-talk@aps.anl.gov
Subject: Re: state notation code flags

Hi Mark,

Are the flags on a monitored variable set whenever the monitored
variable is used in the code, including a pvPut, pvGet, assignment,
calculation, or print statement? Is there a way to test if the flag
is set besides an efTest in a when statement?

Thank you,
Patrick

Mark Rivers wrote:

Hio Patrick,

Here are some code snippets from one of my SNL programs.  It has a
variable nelements assigned to a PV, and a monitor on that PV.  It has
an event flag, nelementsMon that is synced to nelements.  Whenever
nelements changes the event flag will be set.  In the init state I
clear
the event flag, just to be sure it is clear when the SNL code starts
running (after all PVs connect).  I then use efTestAndClear in a when
statement to take actions when that event flag is set, and to clear it.
This works fine for me.

int     nelements;   assign nelements    to "{P}{R}Nelements.VAL";
monitor nelements;
evflag nelementsMon;    sync nelements  nelementsMon;


    /* Initialize things when first starting */
    state init {
        when() {
            /* Clear all event flags */
...

            efClear(nelementsMon);
        } state monitor_inputs
    }


...

    state monitor_inputs {

...

        when(efTestAndClear(nelementsMon) && (nelements>=1)) {
            /* If nelements changes, then change endPulses to this
value,

             * since this is what the user normally wants.  endPulses
can be

             * changed again after changing nelements if this is
desired. */

            if (moveMode == MOVE_MODE_RELATIVE)
                endPulses = nelements;
            else
                endPulses = nelements-1;
            pvPut(endPulses);
        } state monitor_inputs
    }

Mark

________________________________

From: tech-talk-bounces@aps.anl.gov on behalf of Patrick Thomas
Sent: Wed 9/30/2009 10:35 PM
To: tech-talk@aps.anl.gov
Subject: state notation code flags



Hi,

I was wondering if there is a way to track at what point in the state
notation code evflags are getting set and cleared, or if someone could
clarify under what conditions they get set. I'm having trouble with
them

getting set somewhere and not being cleared, but I'm not sure where.

Thank you,
Patrick








References:
state notation code flags Patrick Thomas
RE: state notation code flags Mark Rivers
Re: state notation code flags Patrick Thomas
RE: state notation code flags Mark Rivers
Re: state notation code flags Patrick Thomas
Re: state notation code flags Pete R. Jemian
Re: state notation code flags Patrick Thomas
RE: state notation code flags Mark Rivers
Re: state notation code flags Patrick Thomas
RE: state notation code flags Mark Rivers

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