> I'm trying to setup Midas with the Caen vx2740 VME digitizer board.

welcome to the world of daq and midas! Ben already answered and he will help you with this specific hardware. (we work together)

> #0  0x00005555555c2ee1 in rpc_register_function (id=id@entry=18000, func=func@entry=0x5555555a2790 <jrpc_helper(int, void**)>)
>     at /home/astrocent/workspace/packages/midas/src/midas.cxx:11947

I look at this line in midas and I do not see any problems other than all functions that touch rpc_list are not thread safe,
and calling them at the same time as rpc calls are active will cause memory corruption and crash. This is not a problem
in most programs because rpc_register_function() is usually called once at the beginning of everything, before any RPCs
are received, sent or processed. I filed a bug against this problem. https://bitbucket.org/tmidas/midas/issues/362/rpc_list-is-not-thread-safe

> with is "jrpc"?

I implemented it years ago to allow web pages to call mhttpd (XHR/HTTP) to call user frontends (MIDAS RPC) to perform real-time actions,
i.e. to turn power supplied on or off. "j" stands for "json", but most experiments send very simple commands
and do not use json encoding.

K.O.

I am using the Midas sequencer to run subsequent measurements in a loop, without 
knowing how many iterations in advance. Therefore, I am using the "infinity" 
option. Since I have other commands after the loop, it would be nice to have the 
possibility to break the loop, but let the sequencer then finish the rest of the 
commands. 
Cheers,
Ivo

> I am using the Midas sequencer to run subsequent measurements in a loop, without 
> knowing how many iterations in advance. Therefore, I am using the "infinity" 
> option. Since I have other commands after the loop, it would be nice to have the 
> possibility to break the loop, but let the sequencer then finish the rest of the 
> commands. 
> Cheers,
> Ivo

You can do that with the "GOTO" statement, jumping to the first line after the loop.

Here is a working example:


LOOP runs, 5
     WAIT Seconds 3
     IF $runs > 2
         GOTO 7
     ENDIF
ENDLOOP
MESSAGE "Finished", 1

Best,
Stefan

> You can do that with the "GOTO" statement, jumping to the first line after the loop.
> 
> Here is a working example:
> 
> 
> LOOP runs, 5
>      WAIT Seconds 3
>      IF $runs > 2
>          GOTO 7
>      ENDIF
> ENDLOOP
> MESSAGE "Finished", 1
> 
> Best,
> Stefan

Hoi Stefan

Thanks for your answer. As I understand it, this has to be in the sequence script before 
running. So, in the end, it is not different than just saying "LOOP runs, 2" and 
therefore the number of runs has do be known in advance as well. Or is there an option to 
change the script on runtime? What I would like, is to start a sequence with "LOOP runs, 
infinite" and when I come back to the experiment after falling asleep being able to break 
the loop after the next iteration, but still execute everything after ENDLOOP, i.e. the 
MESSAGE statement in your example. Because if I do a "Stop after current run", this seems 
not to happen. 

Best, Ivo

> > You can do that with the "GOTO" statement, jumping to the first line after the loop.
> > 
> > Here is a working example:
> > 
> > 
> > LOOP runs, 5
> >      WAIT Seconds 3
> >      IF $runs > 2
> >          GOTO 7
> >      ENDIF
> > ENDLOOP
> > MESSAGE "Finished", 1
> > 
> > Best,
> > Stefan
> 
> Hoi Stefan
> 
> Thanks for your answer. As I understand it, this has to be in the sequence script before 
> running. So, in the end, it is not different than just saying "LOOP runs, 2" and 
> therefore the number of runs has do be known in advance as well. Or is there an option to 
> change the script on runtime? What I would like, is to start a sequence with "LOOP runs, 
> infinite" and when I come back to the experiment after falling asleep being able to break 
> the loop after the next iteration, but still execute everything after ENDLOOP, i.e. the 
> MESSAGE statement in your example. Because if I do a "Stop after current run", this seems 
> not to happen. 
> 
> Best, Ivo

First, you have the sequencer button "Stop after current run", but that does of course ot
execute anything after ENDLOOP. 

Second, you can put anything in the IF statement. Like create a variable on the ODB like
/Experiment/Run parameters/Stop loop and set this to zero. Then put in your script:

...
ODBGET /Experiment/Run parameters/Stop loop, flag
IF $flag == 1
   GOTO 7
...

So once you want to stop the loop, set the flag in the ODB to one.

Best,
Stefan

> LOOP runs, 5
> ...
> ENDLOOP

Classical loop constructs usually include "break" (exit the loop) and "continue" (loop again!) 
constructs. I would say it is an unfortunate omission if they are not present in the midas sequencer.

But Stefan is right, of course, both commands are just funny names for "goto".

K.O.

While I know some of those limits/problems have been already been reported from
DEAP (and maybe corrected in the last version), I am recording them here:

Bugs (not working as it should): 
- "SCRIPT" does not seem to take the parameters into account
- The operators for WAIT are incorrectly set:
the default ">=" and ">" are correct, but "<=", "<", "==" and "!=" are all using
">=" for the test. 

Possible improvements:
- in LOOP, how can I get the index of the LOOP? I used an extra variable that I
increment, but it there a better way?
- PARAM is giving "string" (or a bool) whose size is set by the user input. The
side effect is that if I am making a loop starting at "1", the incrementation
will loop at "9" -> "1". If I start at "01", the incrementation will give "2.",
"3.",... "9.", "10"... The later is probably what most people would use.
- ODBGet (and ODBSet?) does seem to be able to take a variable as a path... I
was trying to use an array whose index would be incremented.

These issues have been addressed by Stefan during his visit at Triumf last month.
The latest git has those fixes.

> While I know some of those limits/problems have been already been reported from
> DEAP (and maybe corrected in the last version), I am recording them here:
> 
> Bugs (not working as it should): 
> - "SCRIPT" does not seem to take the parameters into account

Fixed

> - The operators for WAIT are incorrectly set:
> the default ">=" and ">" are correct, but "<=", "<", "==" and "!=" are all using
> ">=" for the test. 

Fixed

> 
> Possible improvements:
> - in LOOP, how can I get the index of the LOOP? I used an extra variable that I
> increment, but it there a better way?

See LOOP doc
 LOOP cnt, 10
   ODBGET /foo/bflag, bb 
   IF $bb==1 THEN
     SET cnt, 10
   ELSE 
     ... 

> - PARAM is giving "string" (or a bool) whose size is set by the user input. The
> side effect is that if I am making a loop starting at "1", the incrementation
> will loop at "9" -> "1". If I start at "01", the incrementation will give "2.",
> "3.",... "9.", "10"... The later is probably what most people would use.

Fixed

> - ODBGet (and ODBSet?) does seem to be able to take a variable as a path... I
> was trying to use an array whose index would be incremented.

To be checked.

> 
> See LOOP doc
>  LOOP cnt, 10
>    ODBGET /foo/bflag, bb 
>    IF $bb==1 THEN
>      SET cnt, 10
>    ELSE 
>      ... 
> 

Looks like we have PE

> > - ODBGet (and ODBSet?) does seem to be able to take a variable as a path... I
> > was trying to use an array whose index would be incremented.
> 
> To be checked.

It does not take a variable as a path, but as an index. So you can do

LOOP i, 5

  WAIT seconds, 3
  ODBSET /System/Tmp/Test[$i], $i

ENDLOOP


And you will get

/System/Tmp/Test
[1] 1
[2] 2
[3] 3
[4] 4
[5] 5


/Stefan 

Hi,

I am having problems with the midas sequencer, here is my code:

1  COMMENT "Example to move a Standa stage"
2  RUNDESCRIPTION "Example movement sequence - each run is one position of a single stage
3  
4  PARAM numRuns
5  PARAM sequenceNumber
6  PARAM RunNum
7  
8  PARAM positionT2
9  PARAM deltapositionT2
10 
11 ODBSet "/Runinfo/Run number", $RunNum
12 ODBSet "/Runinfo/Sequence number", $sequenceNumber
13 
14 ODBSet "/Equipment/Neutron Detector/Settings/Detector/Type of Measurement", 2
15 ODBSet "/Equipment/Neutron Detector/Settings/Detector/Number of Time Bins", 10
16 ODBSet "/Equipment/Neutron Detector/Settings/Detector/Number of Sweeps", 1
17 ODBSet "/Equipment/Neutron Detector/Settings/Detector/Dwell Time", 100000
18 
19 ODBSet "/Equipment/MTSC/Settings/Devices/Stage 2 Translation/Device Driver/Set Position", $positionT2
20 
21 LOOP $numRuns
22  WAIT ODBvalue, "/Equipment/MTSC/Settings/Devices/Stage 2 Translation/Ready", ==, 1
23  TRANSITION START
24  WAIT ODBvalue, "/Equipment/Neutron Detector/Statistics/Events sent", >=, 1
25  WAIT ODBvalue, "/Runinfo/State", ==, 1
26  WAIT ODBvalue, "/Runinfo/Transition in progress", ==, 0
27  TRANSITION STOP
28  ODBInc "/Equipment/MTSC/Settings/Devices/Stage 2 Translation/Device Driver/Set Position", $deltapositionT2
29 
30 ENDLOOP
31 
32 ODBSet "/Runinfo/Sequence number", 0

The issue comes with line 28, the ODBInc does not work, regardless of what number I put I get the following error:

[Sequencer,ERROR] [odb.cxx:7046:db_set_data_index1,ERROR] "/Equipment/MTSC/Settings/Devices/Stage 2 Translation/Device Driver/Set Position" invalid element data size 32, expected 4

I don't see why this should happen, the format is correct and the number that I input is an int.

Sorry if this is a basic question.

Jacob

Thanks for reporting that bug. Indeed there was a problem in the sequencer code which I fixed now. Please try the updated develop branch.

Stefan

> Stefan and I have been working on improving the sequencer editor ...

Looks grand! Congratulations with getting it completed. The previous version was 
my rewrite of the old generated-C pages into html+javascript, nothing to write 
home about, I even kept the 1990-ies-style html formatting and styling as much as 
possible.

K.O.

• A "Reload File" button
  
• Support for patterns in ODBSET, e.g.:
  

  • ODBSET "/Path/value[1,3,5]", 1

  • ODBSET "/Path/value[1-5,7-9]", 1

  • Arbitrary combinations of the above
    
• Support for variable substitution:
  

  • SET GOODCHANNELS, "1-5,7,9"; ODBSET "/Path/value[$GOODCHANNELS]", 1

  • SET BADCHANNELS, "6,8"; ODBSET "/Path/value[!$BADCHANNELS]", 1

  • ODBSET "/Path/value[0-100, except $BADCHANNELS]", 1

• Load a file
  
• Double-click it to edit it, acknowledge the "To edit the sequence it must be opened in an editor tab" dialog
  
• A new tab opens
  
• Edit something, click "Start", acknowledge the "Save and start?" dialog (which pops up even if no changes are made)
  
• Run the script
  
• Double-click to make more changes -> another tab opens
  

SET v, "54"
SET file, "MPPCHV_$v.odb"
ODBLOAD $file

SET v, "54.2"
SET file, "MPPCHV_$v.odb"
ODBLOAD $file

SET v, 54.2
SPRINTF file, "MPPCHV_%f.odb", $v
ODBLOAD $file

ODBLOAD f"MPPCHV_{v:.1f}.odb"

> ODBSET "/Path/value[1,3,5]"
> ODBSET "/Path/value[1-5,7-9]"

we support this array index syntax in several places,
specifically, in javascript odb get and set mjsonrpc RPCs.

> SET GOODCHANNELS, "1-5,7,9"; ODBSET "/Path/value[$GOODCHANNELS]"
> SET BADCHANNELS, "6,8"; ODBSET "/Path/value[!$BADCHANNELS]"
> ODBSET "/Path/value[0-100, except $BADCHANNELS]"

this is very clever syntax, but I have not seen any programming
language actually implement it (not even perl).

there must be a good reason why nobody does this. probably we should not do it either.

but as Stefan said (and my opinion), the route of extending MIDAS sequencer
language until it becomes a superset of python, perl, tcl, bash, javascript
and algol is not a sustainable approach. I once looked at using LUA for this,
but I think basing off an full featured programming language like python
is better.

K.O.

 I once looked at using LUA for this,
> but I think basing off an full featured programming language like python
> is better.

if it came to a vote, my vote would go to Lua: it would allow to do everything needed, 
with much less external dependencies and with much less motivation to over-use the interpreter. 
The CMS experience was very teaching in this respect... 

-- my 2c, regards, Pasha