The odb.c function merge_records() has a fixed size array of 10000 bytes to handle the data and it 
aborts with an assert() if passed data bigger than that. It is called from db_create_record() which 
already allocates a data buffer of correct size for it's operations.
K.O.

Message from John M O'Donnell <odonnell@lanl.gov>

Folks,

The following might be related, if so great, if not sorry for the spam.

We had problems with MIDAS/CAEN_A3818 until two things happened:

1) CAEN found the root cause of a problem, as the A3818 and MIDAS both
used unix alarm signals, resulting in clashes.  CAEN modified the
A3818 driver to have a "no alarm" option.

2) after downloading the modified driver, edit src/a3818.c to #define
USE_MIDAS 1 somewhere near the top.

Hope this helps,

John.

> Message from John M O'Donnell <odonnell@lanl.gov>
>
> the A3818 and MIDAS both used unix alarm signals, resulting in clashes.
>

FWIW, current midas no longer uses alarm signals. See forum messages and git commits about 
removal of cm_watchdog().

K.O.

Dear all,

I have a "slow control" frontend which reads out 100 slow control parameters.
When I'm interactively adding a parameter to a history plot, 
a nice "Add history variable" pops up .. , but with 100 parameters in the list, 
it doesn't fit within the screen... 

The browser becomes passive, and I didn't find any easy way of scrolling.

In the attached example, adding a channel 32 variable becomes rather cumbersome, 
not speaking about channel 99.

Two questions:

a) how do people get around this "no-scrolling" issue? - perhaps there is a workaround

b) how big of a deal is it to add a scroll bar to the "Add history variables" popup ? 
   - I do not know javascript myself, but could find help to contribute..

-- many thanks, regards, Pasha

Have you updated to the current midas version? This issue has been fixed a while ago. Below 
you see a screenshot of a long list scrolled all the way to the bottom.

Revision: Thu Dec 7 14:26:37 2023 +0100 - midas-2022-05-c-762-g1eb9f627-dirty on branch 
develop

Chrome on MacOSX 14.2.1

The fix is actually in "controls.js", so make sure your browser does not cache an old 
version of that file. I usually have to clear my browser history to get the new file from 
mhttpd.

Best regards,
Stefan

> Have you updated to the current midas version? This issue has been fixed a while ago. 

Hi Stefan, thanks a lot! I pulled from the head, and the scrolling works now. -- regards, Pasha

> > Have you updated to the current midas version? This issue has been fixed a while ago. 
> 
> Hi Stefan, thanks a lot! I pulled from the head, and the scrolling works now. -- regards, Pasha

Right, I remember running into this problem, too.

If you have some ideas on how to better present 100500 history variables, please shout out!

K.O.

> If you have some ideas on how to better present 100500 history variables, please shout out!

let me share some thoughts. In a particular case which lead to the original posting, 
I was using a multi-threaded driver and monitoring several pieces of equipment with different device drivers.  
In fact, it was not even hardware, but processes running on different nodes of a distributed computer farm.
To reduce the number of frontends, I was combining together the output of what could've been implemented 
as multiple slow control drivers and got 100+ variables in the list - hence the scrolling experience.

At the same time, a list of control variables per driver could've been kept relatively short.

So if a list of control variables of a slow control frontend were split in a History GUI not only by the 
equipment piece, but within the equipment "folder", also by the driver, that might help improving 
the scalability of the graphical interface. 

May be that is already implemented and it is just a matter of me not finding the right base class / example 
in the MIDAS code

-- regards, Pasha

familiar situation, "too much data", you dice t or slice it, still too much. BTW, you can try to generate history 
plot ODB entries from your program instead of from the history plot editor. K.O.

Dear Stephan,

I am writting on behalf of the LiBeRACE collaboration
at Berkeley/Livermore.

We are trying to use midas (2.0.0) for our acquisition system.
However we had some difficulties to compile it on LINUX Fedora
Core 6 with gcc 4.1.1
I tried to trace back the problem and I found that _syscall0 in
system.c is actually an obsolete call (since gcc 4.x apparently).
Playing with assembly language being behond my competence, I would 
like to know if you ever came across this situation recently and
if you have any suggestion(s).

With my best regards
Julien GIBELIN


------------------------------------------------------
GIBELIN Julien

Lawrence Berkeley National Laboratory
Nuclear Science Division
One Cyclotron Rd.
MS 88R0192
BERKELEY, CA 94720-8101

Tel: +1 (510) 495-2695
Fax: +1 (510) 486-7983
------------------------------------------------------

> Dear Stephan,
> 
> I am writting on behalf of the LiBeRACE collaboration
> at Berkeley/Livermore.
> 
> We are trying to use midas (2.0.0) for our acquisition system.
> However we had some difficulties to compile it on LINUX Fedora
> Core 6 with gcc 4.1.1
> I tried to trace back the problem and I found that _syscall0 in
> system.c is actually an obsolete call (since gcc 4.x apparently).
> Playing with assembly language being behond my competence, I would 
> like to know if you ever came across this situation recently and
> if you have any suggestion(s).

The '_syscall0' function call was replaced by 'syscall' in SVN revision 3583. I
would recommend that you switch to the current SVN version (see
http://ladd00.triumf.ca/~daqweb/doc/midas/html/quickstart.html on how to obtain
the SVN version). If the problem still persists, please let us know.

- Stefan

In midas.c, I noticed that memory is only allocated to the global buffer 
_net_send_buffer by calling realloc() from within the function 
resize_net_send_buffer() (at least this was the only place I could find 
allocation to _net_send_buffer happening). This can cause problems for a couple 
of reasons:

1) _net_send_buffer is not set to NULL when declared. To my understanding, this 
makes the first call to realloc(_net_send_buffer, /*size*/) undefined. When 
passed a pointer that has not previously been allocated, realloc() acts like 
malloc() only if the pointer equal to NULL. Otherwise, the behavior is undefined 
and usually causes a crash.

2) cm_disconect_experiment() calls free(_net_send_buffer) but does not set its 
value to NULL. Thus if a client tries to include more than one 
connect...disconnect cycle within an application, there is undefined behavior 
the next time realloc(_net_send_buffer, ...) gets called.

I think that any potential allocation issues involving _net_send_buffer could be 
solved by:

1) Initializing _net_send_buffer to NULL.

2) In cm_disconnect_experiment(), changing
>   M_FREE(_net_send_buffer); 
to 
>   M_FREE(_net_send_buffer);
>   _net_send_buffer = NULL;

> In midas.c, ...
>
> 1) _net_send_buffer is not set to NULL when declared.

_net_send_buffer is a global variable. All global variables are automatically initialized to zero before the program 
starts.

static char*x; // = NULL; is redundant
char*y=realloc(x, 100);  // x is NULL, usage is correct

> 2) cm_disconect_experiment() calls free(_net_send_buffer) but does not set its 
> value to NULL.

My copy of midas.c (svn rev 5256) sets _net_send_buffer to NULL:

   if (_net_send_buffer_size > 0) { 
      M_FREE(_net_send_buffer); 
      _net_send_buffer_size = 0; 
   } 
 
What version of midas do you have? (svn info .)

K.O.

> > In midas.c, ...
> >
> > 1) _net_send_buffer is not set to NULL when declared.
> 
> _net_send_buffer is a global variable. All global variables are automatically 
initialized to zero before the program 
> starts.
> 
> static char*x; // = NULL; is redundant
> char*y=realloc(x, 100);  // x is NULL, usage is correct
>

Ah,okay. I was not aware of this feature of global variables.

 
> > 2) cm_disconect_experiment() calls free(_net_send_buffer) but does not set 
its 
> > value to NULL.
> 
> My copy of midas.c (svn rev 5256) sets _net_send_buffer to NULL:
> 
>    if (_net_send_buffer_size > 0) { 
>       M_FREE(_net_send_buffer); 
>       _net_send_buffer_size = 0; 
>    } 
>  
> What version of midas do you have? (svn info .)
> 
> K.O.

I have version 5256 also (matches what you posted), but I only see 
_net_send_buffer_size being set to 0, not _net_send_buffer itself. In midas.h, 
M_FREE(x) only expands to free(x) if _MEM_DBG is not defined.

> > > In midas.c, ...
> > >
> > > 1) _net_send_buffer is not set to NULL when declared.
> 
> Ah,okay. I was not aware of this feature of global variables.
> 

RTFM K&R "The C programming language". 
http://en.wikipedia.org/wiki/The_C_Programming_Language

>  
> > > 2) cm_disconect_experiment() calls free(_net_send_buffer) but does not set 
> its value to NULL.
>

Confirmed. Sorry for confusion in my previous message. Set the pointer to NULL after free() is good practice.

But note that calling cm_connect and cm_disconnect multiple times is unusual use of MIDAS and you will most 
likely find more breakage.

K.O.

> 2) cm_disconect_experiment() calls free(_net_send_buffer) but does not set its 
> value to NULL.

Set pointer to NULL after free() in these files:

M       odb.c
M       sequencer.cxx
M       mlogger.cxx
M       mhttpd.cxx
M       midas.c

svn rev 5294
K.O.

Dear guys,

I’m Zhi Li from China, and I’m now working on my graduation project, which now
basically gets stuck in the part of preparing the frontend for my FADC (CAEN
VX1721) using Midas.

Now the current set-up includes a VME crate, a CAEN v2718 (Optical Bridge and
Controller) and a CAEN VX1721(8ch 8bit 500MS/s Waveform digitizer). The hardware
set-up has been finished and I could capture the analog waveform using CAEN
software(wavedump). 

Could anyone please tell me what are the basic things to do for using MIDAS?
I’ve installed MIDAS in PC and it works well for CAMAC, but do I need any extra
hardware module on using VME crate? Also, how to download
Universe-II VME driver?

Thanks,
Li

Hi Li,

You mention that you've got the wavedump working. It suggests that you have a A3818 
interface, can you confirm that?

If so, you can make a Midas frontend using the CAEN libraries to access your VX1721. I can provide you with a frontend example used for the V1720 or V1740. The 
modifications for the VX1721 shouldn't be too hard as most of the CAEN digitizers 
are fortunately based on a similar configuration mechanism.
If you have a Midas CAMAC frontend, the trick would be to replace the CAMAC calls by 
the appropriate CAENComm_xxx() for the equivalent functionality.

Can you remind me what hardware do you have in your lab for acquisition?
CAMAC controller, VME controller etc.

Cheers, PAA

> Dear guys,
> 
> I’m Zhi Li from China, and I’m now working on my graduation project, which now
> basically gets stuck in the part of preparing the frontend for my FADC (CAEN
> VX1721) using Midas.
> 
> Now the current set-up includes a VME crate, a CAEN v2718 (Optical Bridge and
> Controller) and a CAEN VX1721(8ch 8bit 500MS/s Waveform digitizer). The hardware
> set-up has been finished and I could capture the analog waveform using CAEN
> software(wavedump). 
> 
> Could anyone please tell me what are the basic things to do for using MIDAS?
> I’ve installed MIDAS in PC and it works well for CAMAC, but do I need any extra
> hardware module on using VME crate? Also, how to download
> Universe-II VME driver?
> 
> Thanks,
> Li

Hi Pierre,

Thanks for your instructions. Before I run the wavedump software, I need to load a driver file for A2818, thus I think I've got this interface of A2818.

I would be grateful to have a look at the frontend example used for v1720 (closer to v1721 I suppose), would you be so kind to offer me the Makefile as well? I
really want to have a compilable/executable DAQ frontend for vme modules, and know better how to link to CAEN library in the Makefile.

About hardware currently used in the vme crate(A2818), there is a VME controller(V2718, CONET VME Bridge), and a FADC(VX1721 waveform digitizer). I'm now preparing
this DAQ system to compare relative quantum efficiency, timing resolution, 1 pe distribution of photomultipliers, also measure decay time of cosmic muons, and
electron spectrum. Humbly, I want to know your opinion on whether I need additional hardware to finish these experiments.

Thanks,
Li

> Hi Li,
> 
> You mention that you've got the wavedump working. It suggests that you have a A3818 
> interface, can you confirm that?
> 
> If so, you can make a Midas frontend using the CAEN libraries to access your VX1721. I can provide you with a frontend example used for the V1720 or V1740. The 
> modifications for the VX1721 shouldn't be too hard as most of the CAEN digitizers 
> are fortunately based on a similar configuration mechanism.
> If you have a Midas CAMAC frontend, the trick would be to replace the CAMAC calls by 
> the appropriate CAENComm_xxx() for the equivalent functionality.
> 
> Can you remind me what hardware do you have in your lab for acquisition?
> CAMAC controller, VME controller etc.
> 
> Cheers, PAA
> 
> > Dear guys,
> > 
> > I’m Zhi Li from China, and I’m now working on my graduation project, which now
> > basically gets stuck in the part of preparing the frontend for my FADC (CAEN
> > VX1721) using Midas.
> > 
> > Now the current set-up includes a VME crate, a CAEN v2718 (Optical Bridge and
> > Controller) and a CAEN VX1721(8ch 8bit 500MS/s Waveform digitizer). The hardware
> > set-up has been finished and I could capture the analog waveform using CAEN
> > software(wavedump). 
> > 
> > Could anyone please tell me what are the basic things to do for using MIDAS?
> > I’ve installed MIDAS in PC and it works well for CAMAC, but do I need any extra
> > hardware module on using VME crate? Also, how to download
> > Universe-II VME driver?
> > 
> > Thanks,
> > Li

Hi,

I had to apply the attached patch to convince SuSE Linux 12.2 to compile mana.c
gcc version is "(SUSE Linux) 4.6.2"

Problem is that gz{write,close, etc.} expect a 1st argument of type gzFile (see
zlib.h), whereas out_file is FILE*. In fact, out_file is a cast to FILE*, even
in the case when we work on a gzfile (HAVE_ZLIB).

Could you please confirm that the patch is correct, and possibly apply it to trunk?

I haven't checked if mana works as advertised now.

Cheers,


Randolf