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:[email protected]]
Sent: Sat 10/3/2009 12:37 AM
To: Mark Rivers
Cc: [email protected]; [email protected]
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:[email protected]]
Sent: Fri 10/2/2009 7:03 PM
To: [email protected]
Cc: Mark Rivers; [email protected]
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:[email protected]
] Sent:
Thursday, October 01, 2009 5:20 PM
To: Mark Rivers
Cc: [email protected]
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: [email protected] on behalf of
Patrick Thomas
Sent: Wed 9/30/2009 10:35 PM
To: [email protected]
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