Experimental Physics and Industrial Control System

The change I observed between 3.13 and 3.14 did not involve SYNC.
 
In 3.13 the following sequence:
    pvPut(pv)
    efClear(pvEvent)
 
always seemed to work, i.e. the efClear cleared the event flag resulting from the pvPut.
 
But in 3.14 that no longer worked.  My hypothesis is that the event is now arriving after the efClear, whereas previously it must have arrived before the efClear.  Could possibly be because it was previously using a caPendEvent with a longer timeout?
 
Mark
 

________________________________

From: Eric Norum [mailto:[email protected]]
Sent: Sun 10/4/2009 11:21 AM
To: Patrick Thomas
Cc: Mark Rivers; [email protected]
Subject: Re: state notation code flags



Again, that sort of code is not a good idea since it introduces a busy 
loop.   On systems with strict priority-based schedulers (i.e. vxWorks 
and RTEMS) this can cause deadlock.
Mark Rivers' approach of adding an extra qualifier to the when 
statements is a better technique.
It would be good if some SEQ/SNC expert could step in here and explain 
why the SYNC causes two callbacks, and why this behaviour seems to 
have appeared between R3.13 and R3.14.

On Oct 4, 2009, at 11:10 AM, Patrick Thomas wrote:

> As far as I can tell, it seems that the pvPut without SYNC does only 
> one callback, but it may occur sometime after an immediate efClear. 
> However, with the SYNC option it appears to do two callbacks. My 
> workaround is to remove the SYNC option and do the following:
>
> ...
> if (data != new_data) {
>   data = new_data;
>   pvPut(data);
>   while(!(efTestAndClear(dataFlag));
> }
> ...
> I don't know if this is the best way to do it, but it seems to work.
>
> Patrick
>
> Mark Rivers wrote:
>> On this topic I know that I observed a change in the behavior of 
>> monitor events in SNL when I changed from EPICS 3.13 to 3.14.4.  
>> This is a snippet of code from one of my current SNL programs:
>> long read_complete;
>> assign  read_complete to "{P}{Dmm}read_complete.VAL";
>> monitor read_complete;
>> evflag  read_complete_mon;
>> sync    read_complete read_complete_mon;
>>
>>    state read_channel {
>> ...
>>            read_complete=0;
>>            pvPut(read_complete);
>>            efClear(read_complete_mon);
>>            pvPut(dmm_read);
>>        } state single_read_response
>>    state single_read_response {
>>        when(efTestAndClear(read_complete_mon) && read_complete) {
>>            pvPut(Dmm_raw);
>>            done_read = 0;
>>            pvPut(done_read);
>>        } state wait_read
>>    }
>>
>> Back in 2003 when switching from 3.13 to 3.14.4 I made the 
>> following change and CVS log comment to this code:
>> revision 1.5
>> date: 2003/09/02 14:24:34;  author: rivers;  state: Exp;  lines: +2 
>> -2
>> Work around bug (?) in seq for 3.14
>> ----------------------------
>>
>> corvette:2-9/ipApp/src>cvs diff -r1.4 -r1.5 Keithley2kDMM.st
>> Index: Keithley2kDMM.st
>> ===================================================================
>> RCS file: /net/beams-nfs/export/local/cvs/support/ip/ipApp/src/
>> Keithley2kDMM.st,v
>> retrieving revision 1.4
>> retrieving revision 1.5
>> diff -u -r1.4 -r1.5
>> --- Keithley2kDMM.st    2002/11/09 00:47:48     1.4
>> +++ Keithley2kDMM.st    2003/09/02 14:24:34     1.5
>> @@ -370,14 +370,14 @@
>>         } state next_channel
>>     }
>>     state single_read_response {
>> -        when(efTestAndClear(read_complete_mon)) {
>> +        when(efTestAndClear(read_complete_mon) && read_complete) {
>>             pvPut(Dmm_raw);
>>             done_read = 0;
>>             pvPut(done_read);
>>         } state wait_read
>>     }
>> ...
>> In this code I do a pvPut to read_complete, and then immediately 
>> clear the event flag on read_complete_mon.  In an older version of 
>> the sequencer this worked fine, the event flag for the value that 
>> was just written with pvPut was cleared with the efClear.  When 
>> upgrading to 3.14 this stopped working, and I had to add code to 
>> ignore the events for the value that pvPut had just written.  Now 
>> what Patrick has found is that the pvPut can in fact lead to 2 
>> callbacks resulting from the pvPut, not just 1.
>> Mark
>>
>> ________________________________
>>
>> From: [email protected] on behalf of Eric Norum
>> Sent: Sat 10/3/2009 9:59 PM
>> To: Patrick Thomas
>> Cc: [email protected] Techtalk
>> Subject: Re: state notation code flags
>>
>>
>>
>> Yes, it would appear that something in the pvPut causes 
>> pvCaMonitorHandler()  to be invoked twice.
>> I think that the "take away" message from all this is that there is 
>> no way to rely on a a one-to-one correspondence between pvPut calls 
>> and sequencer event flag assertions.
>>
>> On Oct 3, 2009, at 9:28 PM, Patrick Thomas wrote:
>>
>>
>>> Maybe the pvPut sends two monitors, at varying times apart?
>>>
>>> Eric Norum wrote:
>>>
>>>> I added a
>>>>   dbpf "H3:TEST_PUT" 1
>>>> to the st.cmd script before starting the sequencer.   The pvPut 
>>>> in the sequencer program now results in pvCaMonitorHandler() 
>>>> being invoked just once.   So, I think you have to live with the 
>>>> fact that a single 'pvPut' can result in an 'sync'd sequencer 
>>>> event flag being set more than once (once from status change, 
>>>> once from value change).
>>>>
>>>> With the dbpf done first, I've run the IOC with following program 
>>>> 500 times without getting a 'flag set' message.
>>>>
>>>> program sncTest
>>>>
>>>> float test_put;
>>>> assign test_put to "H3:TEST_PUT";
>>>> monitor test_put;
>>>> evflag test_putEvent;
>>>> sync test_put test_putEvent;
>>>>
>>>> ss ss1 {
>>>>   state init {
>>>>       when () {
>>>>           test_put = 40;
>>>>           pvPut(test_put, SYNC);
>>>>       } state clear
>>>>   }
>>>>
>>>>   state clear {
>>>>       when(efTestAndClear(test_putEvent)) { } state wait
>>>>   }
>>>>
>>>>   state wait {
>>>>       when (efTest(test_putEvent)) {
>>>>           printf("flag set\n");
>>>>       } state loop
>>>>   }
>>>>
>>>>   state loop {
>>>>       when (delay(1000)) { } state loop
>>>>   }
>>>> }
>>>>
>>>>
>>>> On Oct 3, 2009, at 7:56 PM, Eric Norum wrote:
>>>>
>>>>
>>>>> Tracking this down a little farther.  It appears that the 
>>>>> pvCaMonitorHandler in <sequencerTop>/src/pv/pvCa.cc is being 
>>>>> invoked twice.  Perhaps once when the PV status changes from 
>>>>> 'invalid' and perhaps once when the PV value is changed?  If 
>>>>> these happen on either side of the efTestAndClear call then 
>>>>> you'll get the 'flag set' message.
>>>>>
>>>>> On Oct 3, 2009, at 7:32 PM, Patrick Thomas wrote:
>>>>>
>>>>>
>>>>>> It happens frequently on this one too, and also prints "should 
>>>>>> clear it here"
>>>>>>
>>>>>> program sncTest
>>>>>>
>>>>>> float test_put;
>>>>>> assign test_put to "H3:TEST_PUT";
>>>>>> monitor test_put;
>>>>>> evflag test_putEvent;
>>>>>> sync test_put test_putEvent;
>>>>>>
>>>>>> ss ss1 {
>>>>>>   state init {
>>>>>>       when () {
>>>>>>           efClear(test_putEvent);
>>>>>>           test_put = 40;
>>>>>>           pvPut(test_put, SYNC);
>>>>>>                  } state clear
>>>>>>   }
>>>>>>
>>>>>>   state clear {
>>>>>>       when(efTestAndClear(test_putEvent)) {
>>>>>>           printf("should clear it here\n");
>>>>>>           efClear(test_putEvent);
>>>>>>       } state wait
>>>>>>   }
>>>>>>
>>>>>>   state wait {
>>>>>>       when (efTest(test_putEvent)) {
>>>>>>           printf("flag set\n");
>>>>>>           sleep(500);
>>>>>>       } state wait
>>>>>>   }
>>>>>> }
>>>>>>
>>>>>>
>>>>>>
>>>>>> Eric Norum wrote:
>>>>>>
>>>>>>> Clarification.  I ran the example, *with busy loops removed*.
>>>>>>> On Oct 3, 2009, at 6:30 PM, Eric Norum wrote:
>>>>>>>
>>>>>>>
>>>>>>>> I ran the example in a script.  It's been started 250 times 
>>>>>>>> now and never printed, "flag set".
>>>>>>>>
>>>>>>>> On Oct 3, 2009, at 5:37 PM, Patrick Thomas wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>> I'm sorry, I should clarify. It doesn't print the message 
>>>>>>>>> after sitting there for a long time. It sometimes prints it 
>>>>>>>>> when it is started over again multiple times.
>>>>>>>>> -Patrick
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Eric Norum wrote:
>>>>>>>>>
>>>>>>>>>> I forgot to mention, that I tried your example (with busy 
>>>>>>>>>> loops removed) on R3.14.11.  My test IOC has been sitting 
>>>>>>>>>> there for half an hour now without printing the message.
>>>>>>>>>>
>>>>>>>>>> On Oct 3, 2009, at 5:13 PM, Eric Norum wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> There seems to be a fundamental misunderstanding  in your 
>>>>>>>>>>> use of the sequencer.  The default action, if no state 
>>>>>>>>>>> transition 'when' statement is true, is to stay in the 
>>>>>>>>>>> same state waiting for a statement to come true.  Your 
>>>>>>>>>>> examples have lots of statements like:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> state clear {
>>>>>>>>>>>>   when(efTestAndClear(test_putEvent)) {
>>>>>>>>>>>>       efClear(test_putEvent);
>>>>>>>>>>>>   } state wait
>>>>>>>>>>>>
>>>>>>>>>>>>   when () {
>>>>>>>>>>>>   } state clear
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>> The above code is bad.  It sets the sequencer into a busy 
>>>>>>>>>>> loop consuming all available CPU.
>>>>>>>>>>> I think what you want is the following:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> state clear {
>>>>>>>>>>>>   when(efTestAndClear(test_putEvent)) {
>>>>>>>>>>>>       efClear(test_putEvent);
>>>>>>>>>>>>   } state wait
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>> This code blocks the sequencer until something 
>>>>>>>>>>> 'interesting' happens at which point it rescans the 'when' 
>>>>>>>>>>> statements and checks to see if any of them are now true.
>>>>>>>>>>>
>>>>>>>>>>> I suspect that your 'flag' problem is occurring because 
>>>>>>>>>>> the busy loops you've constructed are preventing other 
>>>>>>>>>>> threads from getting the CPU they need.
>>>>>>>>>>>
>>>>>>>>>>> On Oct 3, 2009, at 4:46 PM, Patrick Thomas wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> Hi Mark,
>>>>>>>>>>>>
>>>>>>>>>>>> Why does this still sometimes print out the flag?
>>>>>>>>>>>>
>>>>>>>>>>>> program sncTest
>>>>>>>>>>>>
>>>>>>>>>>>> float test_put;
>>>>>>>>>>>> assign test_put to "H3:TEST_PUT";
>>>>>>>>>>>> monitor test_put;
>>>>>>>>>>>> evflag test_putEvent;
>>>>>>>>>>>> sync test_put test_putEvent;
>>>>>>>>>>>>
>>>>>>>>>>>> ss ss1 {
>>>>>>>>>>>> state init {
>>>>>>>>>>>>   when () {
>>>>>>>>>>>>       efClear(test_putEvent);
>>>>>>>>>>>>
>>>>>>>>>>>>       test_put = 40;
>>>>>>>>>>>>       pvPut(test_put, SYNC);
>>>>>>>>>>>>   } state clear
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> state clear {
>>>>>>>>>>>>   when(efTestAndClear(test_putEvent)) {
>>>>>>>>>>>>       efClear(test_putEvent);
>>>>>>>>>>>>   } state wait
>>>>>>>>>>>>
>>>>>>>>>>>>   when () {
>>>>>>>>>>>>   } state clear
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> state wait {
>>>>>>>>>>>>   when (efTest(test_putEvent)) {
>>>>>>>>>>>>       printf("flag set\n");
>>>>>>>>>>>>   } state loop
>>>>>>>>>>>>
>>>>>>>>>>>>   when () {
>>>>>>>>>>>>   } state wait
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>> state loop {
>>>>>>>>>>>>   when () {
>>>>>>>>>>>>   } state loop
>>>>>>>>>>>> }
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> 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:[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:thomas_p@ligo-
>>>>>>>>>>>>>> wa.caltech.edu]
>>>>>>>>>>>>>> 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
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Eric Norum <[email protected]>
>>>>>>>>>>> Advanced Photon Source
>>>>>>>>>>> Argonne National Laboratory
>>>>>>>>>>> (630) 252-4793
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>> --
>>>>>>>> Eric Norum <[email protected]>
>>>>>>>> Advanced Photon Source
>>>>>>>> Argonne National Laboratory
>>>>>>>> (630) 252-4793
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>> --
>>>>> Eric Norum <[email protected]>
>>>>> Advanced Photon Source
>>>>> Argonne National Laboratory
>>>>> (630) 252-4793
>>>>>
>>>>>
>>>>>
>>
>> --
>> Eric Norum <[email protected]>
>> Advanced Photon Source
>> Argonne National Laboratory
>> (630) 252-4793
>>
>>
>>
>>
>>
>

--
Eric Norum <[email protected]>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793

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 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

Re: state notation code flags Patrick Thomas

Re: state notation code flags Eric Norum

Re: state notation code flags Eric Norum

Re: state notation code flags Patrick Thomas

Re: state notation code flags Eric Norum

Re: state notation code flags Eric Norum

Re: state notation code flags Patrick Thomas

Re: state notation code flags Eric Norum

Re: state notation code flags Eric Norum

Re: state notation code flags Patrick Thomas

RE: state notation code flags Mark Rivers

Re: state notation code flags Eric Norum

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