There is no requirement that you pair an EQ_PERIODIC with an EQ_TRIGGER. Take for exmaple

  midas/examples/experiment/frontend.cxx

and remove there the triggered event. The frontend runs happily with the periodic event only (I just tried that myself). You have probably some problem in 
your event definition. Start with the running example frontend, and add your code line by line until you see the problem.

Stefan

> Actual result:
> The key picker does not close.

Thanks for reporting that bug. It has been fixed in the current commit (installed already on megon02)

Stefan

> Another more minor visual problem is the edit-on-start dialog. There seems to be no upper bound to the 
> size of the text box. In the attached screenshot, ShortString has a maximum length of 32 characters, 
> LongString has 255. Both are empty at the time of the screenshot. Maybe, the size should be limited to a 
> reasonable width.

I limited the input size now to (arbitrarily) 100 chars. The string can still be longer than 100 chars, and you start then scrolling inside the input box. Let me know if 
that's ok this way.

Stefan

The atexit() function has been implemented in the current develop branch of midas, see

  https://daq00.triumf.ca/MidasWiki/index.php/Sequencer#ATEXIT_subroutine


Stefan

A new slow control mini-framework has been developed for MIDAS and been successfully tested in the Mu3e experiment. It 
might be suited for other experiments as well.

Background

Since the late 90’s we have the three-tier bases slow control framework in MIDAS with class drivers, device drivers and bus 
drivers. While it was used successfully since many years, it is complicated to understand and limited in its flexibility. If we 
have a HV device with a demand value, a measured voltage and a current it’s fine, but if we want to control more things like 
trip voltage, temperature and status readout etc. it soon hits its limits. With the development of the new odbxx API 
(https://daq00.triumf.ca/MidasWiki/index.php/Odbxx) there is now an opportunity to make everything much simpler.

Design principles

Instead of a three-tier system, the new “mdev” framework (“m”idas “dev”ices) uses a simple base class which is attached to 
a certain MIDAS equipment. It implements five simple functions:

- odb_setup() to setup /Equipment/<name>/Settings and /Equipment/<name>/Variables to its desired structure

- init() to initialize the slow control device

- exit() to close the connection to the device

- loop() which is called periodically to read the device

- read_event() which returns a MIDAS event going to the data stream

A device driver inherits from this base class and implements the functions. A simple example can be found in 

  midas/drivers/mdev/mdev_mscb.[h,cxx]

for the MSCB field bus system used at TRIUMF and PSI. It basically boils down to two calls:

Init:
   m_variables.connect(“/Equipment/<name>/Variables”);
   m_variables[“Output”].watch(midas::odb &o) {
      m_mscb[“HV”] = o[0]; // transfer value from ODB to MSCB device
   }

Reading a value in the loop function:
   m_variables[“Input”][0] = m_mscb[“HVMeas”];

The member variable m_variables is a midas::odb variable attached to the “Input” and “Output” variables in the ODB. The 
watch() functions executes the lambda function whenever the “Output” in the ODB changes. It then simply transfers the new 
value to the device. The reading of measured values just work in the other direction from the device to the ODB.

If you look at the mdev_mscb.cxx code, you see of course some more things like connecting to the MSCB device with proper 
error handling, looping over several devices and variables, setting up the “Setting” directory in the ODB to define labels for 
all variables. In addition we have a mirror for output variables, so that new values are only sent to the device if they differ 
from the previous variable (needed to reduce some communication traffic). 

The midas/drivers/mdev directory contains also an example frontend in the mfe.cxx framework, but this is no a requirement. 
The mdev framework can also be used in the tmfe framework and others as well. Please note how compact the frontend 
code now looks.

User interface

Since the beginning, MIDAS allows access to the the slow control devices through the “equipment” page (on the main status 
page, click on one equipment). A few more options can control now the behavior of this page, allowing quite some flexibility 
without having to write a dedicated custom page (which of course can still be done). Attached is an example from Mu3e where 
the details of the equipment display are controlled through some options in the setting subdirectory as described in 
https://daq00.triumf.ca/MidasWiki/index.php//Equipment_ODB_tree (especially the “grid display”, “Editable” and “Format” 
flags).

Conclusions

The new “mdev” framework offers a compact and effective way to communicate from MIDAS to slow control devices. Since 
all interface code is now not “hidden” any more in system class and device drivers, the user has much higher flexibility in 
controlling different devices. If a device has a new parameter, the user can add a single line of code to connect this 
parameter to an ODB entry.

The framework is very simple and misses some features of the old system. Ramping of HV voltages and current trips are not 
available in the framework (like with the old HV class driver), but modern devices usually implement this in hardware which 
is much better. The new framework is not multi-threaded, but modern devices are these day much faster than in the ‘90s. 
Since the ODB is thread save, nothing prevents us from putting a device readout into its own thread in the frontend.

We will use the new system for all devices in Mu3e, with probably some new features being added soon, so stay tuned.

/Stefan

These kind of alarm conditions have been implemented and committed. The documentation at 

  https://daq00.triumf.ca/MidasWiki/index.php/Alarm_System

has been updated.

/Stefan

We had the case in MEG that some alarms were actually just warnings, not very severe. This happens for example if we calibrate our detector 
once every other day and modify the hardware which actually triggers the alarm for about an hour or so.

The problem with this is now that the alarm sounds every few minutes, and people get annoyed during that hour. They turn down the volume 
of their speakers, or even disable the alarm sound. If the detector gets back into the default mode again, they might forget to re-enable the 
alarm, which causes some risk. 

Turning down the volume is also not good, since during that hour we could have a "real" alarm on which people have to react quickly in order 
not destroy the detector.

The art is now to configure the alarm system in a way that "normal" changes do not annoy people or cover up really severe alarms. After long 
discussions we came to following conclusion: We need a special class of alarm (let's call it 'warning') which does not annoy people. The 
warning should be visible on the screen, but not ring the alarm bell. 

While we have different alarm classes in midas, which let us customize the frequency of alarms and the screen colors, all alarms or warnings 
ring the alarm sound right now. This can be changed in the browser under "Config/Alarm sound" but that switch affects ALL alarms, which is 
not what we want.

The idea we came up with was to add a flag "Alarm sound" to the alarm classes. For the 'warning' we can then turn off the alarm sound, so 
only the banner is shown on top of the screen, and the spoken message is generated every 15 mins to remind people, but not to annoy them.

I added this "Alarm sound" flag in the branch feature/alarm_sound so everybody can test it. The downside is that all "Alarm/Classs/xxx" need 
to be modified to add this flag. While the new code will add this flag automatically (with a default value of 'true'), the size of the alarm class 
record changes by four bytes (one bool). Therefore, all running midas programs will complain about the changed size, until they get 
recompiled. 

Therefore, to test the new feature, you have to checkout the branch and  re-compile all midas programs you use, otherwise you will get errors 
like 

  Fixing ODB "/Alarms/Classes/Alarm" struct size mismatch (expected 352, odb size 348)

I will keep the branch for a few days for people to try it out and report any issue, and later merge it to develop.

Stefan

I had put in a check which limits the range to 7d into the past if you press the "play" button, but now I'm not sure why this was needed. I removed it again and 
things seem to be fine. Change is committed to develop.

Stefan

Another modification has been done to the alarm system. 

We have often cases where an alarm is triggered on some readout noise. Like an analog voltage just over the alarm threshold for a very short period of time, triggered sometimes from environmental 
electromagnetic effects like turning on the light. 

To mitigate this problem, an "alarm trigger count" has been implemented. Every alarm has now a variable "Trigger count required". If this value is zero (the default), the alarm system works as before. If this 
value is nowever set to a non-zero value N, the alarm limit has to be met on N consecutive periods in order to trigger the alarm. Each alarm has a "Check interval" which determines the period of the alarm 
checking. If one has for example:

Check interval = 10
Trigger count required = 3

then the alarm condition has to be met for 3 consecutive periods of 10 seconds each, or for 30 seconds in total. 

The modification has been merged into the develop branch, and people have to be aware that the alarm structures in the ODB changed. The current code tries to fix this automatically, but it is important 
that ALL MIDAS CLIENTS GET RE-COMPILED after the new code is applied. Otherwise we could have "new" clients expecting the new ODB structure, and some "old" clients expecting the old structure, 
then both types of clients would fight against each other and change the ODB structure every few seconds, leading to tons of error messages. So if you pull the current develop branch, make sure to re-
compile ALL midas clients.

/Stefan

Hi Pavel,

have you looked into 

  cm_set_transition_sequence()

which let's you define the sequence number for every midas client. You give any number between 1 and 1000 (default is 500 for frontends I believe).

The default value of 500 is defined in mfe.cxx:2641 where you have 500 for all four transitions, but it can be overwritten in the frontend_init function via 
cm_set_transition_sequence(). Since you have separate values for the start and stop transition, you can get the different sequencing for both transitions as you need. Like set 
all type A to 400, type B to 600 for TR_START, and set type A to 600 and type B to 400 for TR_STOP.

Since this works on the midas client level, it should also work for the tmfe.cxx framework. I'm however not sure if you have a similar default of 500 as in mfe.cxx:2641. But K.O. 
should know.

Best,
Stefan 

After some iterations, we merged the branch with the new build scheme. Now you can compile any midas program as described at

  https://bitbucket.org/tmidas/midas/pull-requests/48?link_source=email

A default CMakeLists.txt file can look like this:

cmake_minimum_required(VERSION 3.17)
project(example)
find_package(Midas REQUIRED PATHS $ENV{MIDASSYS})
add_executable(example example.cpp)
target_link_libraries(example midas::midas)


Which is much simpler than what we had before. The trick now is that the find_package() retrieves all include and link files automatically. 
There are different targets:

midas::midas              - normal midas program
midas::midas-shared       - normal midas programs using the shared midas library
midas::mfe                - old style mfe.cxx frontend
midas::mfed               - newer style frontend using mfed.cxx
midas::mscb               - programs using MSCB system
midas::drivers            - slow control program using any of the standard midas drivers

We are not absolutely sure that all midas installations will work that way, so far we have tested it on RH8, MacOSX with cmake version 
3.29.5.

Comments and bug reports are welcome as usual.

Alex and Stefan

   {"Trigger",               /* equipment name */
      {1, 0,                 /* event ID, trigger mask */
         "SYSTEM",           /* event buffer */
         EQ_POLLED,          /* equipment type */
         0,                  /* event source */
         "MIDAS",            /* format */
         TRUE,               /* enabled */
         RO_RUNNING |        /* read only when running */
         RO_ODB,             /* and update ODB */
         100,                /* poll for 100ms */
         0,                  /* stop run after this event limit */
         0,                  /* number of sub events */
         0,                  /* don't log history */
         "", "", "", "", "", 0, 0},
      read_trigger_event,    /* readout routine */
      10000000,              /* write cache size */
   },

fe_set_write_case(int size);

 > All this is kind of reasonable, as only two settings of write cache size are useful: 0 to 
> disable it, and 10 Mbytes to limit semaphore locking rate to reasonable value for all event 
> rate and size values practical on current computers.

Indeed KO is correct that only 0 and 10MB make sense, and we cannot mix it. Having the cache setting in the equipment table is 
cumbersome. If you have 10 slow control equipment (cache size zero), you need to add many zeros at the end of 10 equipment 
definitions in the frontend. 

I would rather implement a function or variable similar to fEqConfWriteCacheSize in the tmfe framework also in the mfe.cxx 
framework, then we need only to add one line llike

gEqConfWriteCacheSize = 0;

in the frontend.cxx file and this will be used for all equipments of that frontend. If nobody complains, I will do that in April when I'm 
back from Japan.

Stefan

> > ALL MIDAS CLIENTS GET RE-COMPILED after the new code is applied.
> 
> Usually we expect that it is "safe" to update to the latest version of MIDAS.
> 
> In the sense that we do not have to track down every single frontend
> and rebuild it. We have several experiments where tracking down the source code
> and rebuilding a frontend takes more than 5 seconds. In many cases these are
> 10 year old executables that worked just fine through many updates of MIDAS
> without having to rebuild them.
> 
> So any binary incompatible change is best avoided and must be clearly announced.
> 
> The present binary-incompatible change is this commit:
> https://bitbucket.org/tmidas/midas/commits/5899f1657ba31121c9f420a824b3c6c13b173988
> 
> I tagged the last commit before this change as: midas-2024-12-a

Here are my replies:

- this is not a binary incompatibility, but a incompatibility of the /Alarm record which got two more variables. Old 
frontends will complain during their structure check and remove the two variables, new frontend will then complain as 
well and add the two variables. This will go in circles, that why all frontends need to be recompiled if the new code is 
used

- I did clearly announce this change in the forum. Is there another location where I should communicate that?

- The extension is not there "just for fun" but needed by several experiments which experience spurious alarms 
triggered by some noisy signals. Requiring an value to be above a limit for a certain minimum time fixes many issues in 
many experiments here at PSI, this is why it has been implemented, even if it causes work for everybody with re-
compilation.

- If there are frontend programs which have not been re-compiled for ten years, I think it is very unlikely that these 
experiments need the latest cutting edge version of midas. The can safely stick to your tag midas-2024-12-a and not 
experience the issue of different /Alarm trees.

Stefan

> Unnamed person who added this clever bit of c++ coding, please fix this compiler warning. Stock g++ on Ubuntu LTS 24.04. Thanks in advance!
> 
> /home/olchansk/git/midas/src/system.cxx: In function ‘std::string ss_execs(const char*)’:
> /home/olchansk/git/midas/src/system.cxx:2256:43: warning: ignoring attributes on template argument ‘int (*)(FILE*)’ [-Wignored-attributes]
>  2256 |    std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
> 
> K.O.

Replace the code with:

   auto pclose_deleter = [](FILE* f) { pclose(f); };
   auto pipe = std::unique_ptr<FILE, decltype(pclose_deleter)>(
      popen(cmd, "r"),
      pclose_deleter
   );


Hope this is now warning-free.

Stefan

> bitbucket automatic builds were broken after mfe.cxx started printing some additional messages added in commit
> https://bitbucket.org/tmidas/midas/commits/0ae08cd3b96ebd8e4f57bfe00dd45527d82d7a38
> 
> this is now fixed. to check if your changes will break automatic builds, before final push, please do:
> 
> make clean
> make mini -j
> make cmake -j
> make test

Unfortunately we will break the automatic build each time a program outputs one different character, which even might happen if we add a line of code and 
a cm_msg() gets produced with a different line number. Is there a standard way to update testexpt.example (like "make testexpt" or so). Should be trigger 
the update of testexpt.example before each commit via a hook? 

Stefan

I hopefully fixed the waring (narrowing down from size_t to int). Please double check with your compiler.

Stefan

> Hello,
> 
> Does anyone have experience with writing a MIDAS frontends to communicate with a device that operates using LabView (e.g. superconducting magnets, cryostats etc.). Any information or experience regarding this would be highly appreciated.
> 
> thanks,
> Zaher

We do have a superconducting magnet from Cryogenic, UK, which comes with a LabView control program on a Windows PC. I did the only reasonable with this: trash it in the waste basket. Do NOT use Labveiw for anything which should run more than 24h in a row. Too many bad experiences with LabView control programs 
for separators at PSI and other devices. Instead of the Windows PC, we use MSCB devices and RasperryPis to communicate with the power supply directly, which has been proven to be much more stable (running for years without crashes). I'm happy to share our code with you.

Stefan