> Is there now some other mechanism to hide the start and stop buttons?
> Note that this is for a pure slow control system that does not take runs.

Just wanted to add that I realize that this can be done by copying
status.html and/or midas.css to the experiment directory and then modifying
them/it, but wonder if the is some other preferred way.

Hi Stefan,

> Indeed the ODB settings are obsolete.

I just applied for an account for the wiki.
I'll try add a note regarding this change.

> Now that the status page is fully dynamic 
> (JavaScript), it's much more powerful to modify the status.html page directly. You 
> can not only hide the buttons, but also remove the run numbers, the running time, 
> and so on. This is much more flexible than steering things through the ODB.

Very true. Currently I copied the resources/midas.css into the experiment directory and appended:

#runNumberCell { display: none;}
#runStatusStartTime { display: none;}
#runStatusStopTime { display: none;}
#runStatusSequencer { display: none;}
#logChannel { display: none;}

See screenshot attached. :-)

But if feels a little clunky to copy the whole file just to add five lines.
It might be more elegant if status.html looked for a user css file in addition
to the default ones.

> If there is a general need for that, I can draft a "non-run" based status page, but 
> it's a bit hard to make a one-fits-all. Like some might even remove the logging 
> channels and the clients, but add certain things like if their slow control front-
> end is running etc.

The logging channels are easily removed with the css (see attachment), but it might be
nice if the string "Run Status" table title was also configurable by css. For this
slow control system I'd probably change it to something like "GSC Status". Again
this is a minor thing, I could trivially do this by copying the resources/status.html
to the experiment directory and editing it.

Lots of fun new stuff migrating from circa 2012 midas to midas-2022-05-c :-)

Cheers,

Nick.

Hi

> > > Indeed the ODB settings are obsolete.
> > 
> > I just applied for an account for the wiki.
> > I'll try add a note regarding this change.
> 
> Please coordinate with Ben Smith at TRIUMF <bsmith@triumf.ca>, who coordinates the documentation. 

I will tread lightly. 

> I would not go to change the CSS file. You only can hide some tables. But in a while I'm sure you
> want to ADD new things, which you only can do by editing the status.html file. You don't have to
> change midas/resources/status.html, but can make your own "custom status", name it differently, and
> link /Custom/Default in the ODB to it. This way it does not get overwritten if you pull midas.

We have *many* custom pages. The submenus on the status page:

&#9656; FGD
&#9656; TPC
&#9656; TRIPt

hide custom pages with all sorts of good stuff.

> > The logging channels are easily removed with the css (see attachment), but it might be
> > nice if the string "Run Status" table title was also configurable by css. For this
> > slow control system I'd probably change it to something like "GSC Status". Again
> > this is a minor thing, I could trivially do this by copying the resources/status.html
> > to the experiment directory and editing it.
> 
> See above. I agree that the status.html file is a bit complicated and not so easy to understand
> as the CSS file, but you can do much more by editing it.

I may end up doing this since the events and data columns do not provide particularly
useful information in this instance. But for now, the css route seems like a quick and
fairly clean way to remove irrelevant stuff from a prominent place at the top of the page.
 
> > Lots of fun new stuff migrating from circa 2012 midas to midas-2022-05-c :-)
> 
> I always advise people to frequently pull, they benefit from the newest features and avoid the
> huge amount of work to migrate from a 10 year old version.

The long delay was not my choice. The group responsible for the system departed in 2018, and
and were not replaced by the experiment management. Lack of personnel/expertise resulted in
a "if it's not broken then don't fix it" situation. Eventually, the need to update the PCs/OSs
and the imminent introduction of new sub-detectors resulted people agreeing to the update. 

Cheers,

Nick.

Hi,

> What's the best way to make these messages go away? 
1.
> - Change the logic in db_validate_and_repair_key_wlocked() to not worry if keys are 10+ years old? 
2.
> - Write a script to "touch" all the old keys so they've been modified recently?
3.
> - Something else?

I wondered about this just under a year ago, and Konstantin forwarded my query here:
https://daq00.triumf.ca/elog-midas/Midas/2470

I am now of the opinion that 2 is not a good approach since it removes potentially
useful information.

I think some version of 1. is the correct choice. Whatever it fix is, I think it
should not care that timestamps of when variables are set are "old" (or at least
it should be user configurable via some odb setting).

Nick.

Dear Midas experts,

I noticed that a check was added to mfe.cxx in 1961af0d6:

+      /* check for consistent common settings */
+      if ((eq_info->read_on & RO_STOPPED) &&
+          (eq_info->eq_type == EQ_POLLED ||
+           eq_info->eq_type == EQ_INTERRUPT ||
+           eq_info->eq_type == EQ_MULTITHREAD ||
+           eq_info->eq_type == EQ_USER)) {
+         cm_msg(MERROR, "register_equipment", "Events \"%s\" cannot be read when run is stopped (RO_STOPPED flag)", equipment[idx].name);
+         return 0;
+      }

This commit was by Stefan in May 2022.

A commit few days later, 28d9c96bd, removed the "return 0;", and updated the
error message to:

"Equipment \"%s\" contains RO_STOPPED or RO_ALWAYS. This can lead to undesired side-effect and should be removed."

So such FEs can run but there is still an error at start up. The 
documentation at https://daq00.triumf.ca/MidasWiki/index.php/ReadOn_Flags
states with RO_STOPPED "Readout Occurs" "Before stopping run".
Which seems to indicate that the removing the RO_STOPPED bit from a SC FE
would just result in an additional read not happening just prior to a run
stop. However reading scheduler() in mfe.cxx I see in the the main loop:

 if (run_state == STATE_STOPPED && (eq_info->read_on & RO_STOPPED) == 0) 
    continue;

So it seems to me that the a EQ_PERIODIC equipment needs RO_STOPPED to be set
otherwise it will not read out data while there is no DAQ run.

Can someone explain the purpose of this check and error message? Perhaps it
was put in place with only DAQ FEs, not SC FEs in mind? And should the 
documentation in the wiki actually be "s/Before stopping run/While run is stopped/"?

Thanks,

Nick.

I think this may only be an issue on the development branch.
Can you confirm that that is what you are using?

If so, I suggest you try the most recent stable tag 2022-05-c.

> Dear experts,
> I am a new user of MIDAS. I try to follow the instruction from 
> https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux
> to install MIDAS in Fedora 39.
> 
> When I try to have a try in the section of "Clients run on Localhost only"
> https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux#Clients_run_on_Localhost_only
> 
> I get the error of "undefined reference to" several variables in the mfe.cxx. For example the variable "max_event_size_frag". May I know any idea about this issue? Thank you.
> 
> 
> Best,
> Terry

I just discovered https://bitbucket.org/tmidas/midas/issues/338/mfec-ro_stopped-is-now-forbidden

> Dear Midas experts,
> 
> I noticed that a check was added to mfe.cxx in 1961af0d6:
> 
> +      /* check for consistent common settings */
> +      if ((eq_info->read_on & RO_STOPPED) &&
> +          (eq_info->eq_type == EQ_POLLED ||
> +           eq_info->eq_type == EQ_INTERRUPT ||
> +           eq_info->eq_type == EQ_MULTITHREAD ||
> +           eq_info->eq_type == EQ_USER)) {
> +         cm_msg(MERROR, "register_equipment", "Events \"%s\" cannot be read when run is stopped (RO_STOPPED flag)", equipment[idx].name);
> +         return 0;
> +      }
> 
> This commit was by Stefan in May 2022.
> 
> A commit few days later, 28d9c96bd, removed the "return 0;", and updated the
> error message to:
> 
> "Equipment \"%s\" contains RO_STOPPED or RO_ALWAYS. This can lead to undesired side-effect and should be removed."
> 
> So such FEs can run but there is still an error at start up. The 
> documentation at https://daq00.triumf.ca/MidasWiki/index.php/ReadOn_Flags
> states with RO_STOPPED "Readout Occurs" "Before stopping run".
> Which seems to indicate that the removing the RO_STOPPED bit from a SC FE
> would just result in an additional read not happening just prior to a run
> stop. However reading scheduler() in mfe.cxx I see in the the main loop:
> 
>  if (run_state == STATE_STOPPED && (eq_info->read_on & RO_STOPPED) == 0) 
>     continue;
> 
> So it seems to me that the a EQ_PERIODIC equipment needs RO_STOPPED to be set
> otherwise it will not read out data while there is no DAQ run.
> 
> Can someone explain the purpose of this check and error message? Perhaps it
> was put in place with only DAQ FEs, not SC FEs in mind? And should the 
> documentation in the wiki actually be "s/Before stopping run/While run is stopped/"?
> 
> Thanks,
> 
> Nick.

Hello,

I've noticed that SC FEs that use the TMFE class with midas-2022-05-c often report errors when calling TMFE:Sleep().
The error is :

[tmfe.cxx:1033:TMFE::Sleep,ERROR] select() returned -1, errno 22 (Invalid argument).

This seems to happen in two different ways:

1. Error being reported repeatedly
2. Occasional single errors being reported

When the first of these presents, we typically restart the FE to "solve" the problem.
Case 2. is typically ignored.

The code in question is:

void TMFE::Sleep(double time)
{
   int status;
   fd_set fdset;
   struct timeval timeout;
      
   FD_ZERO(&fdset);
      
   timeout.tv_sec = time;
   timeout.tv_usec = (time-timeout.tv_sec)*1000000.0;

   while (1) {
      status = select(1, &fdset, NULL, NULL, &timeout);
#ifdef EINTR
      if (status < 0 && errno == EINTR) {
         continue;
      }
#endif
      break;
   }
      
   if (status < 0) {
      TMFE::Instance()->Msg(MERROR, "TMFE::Sleep", "select() returned %d, errno %d (%s)", status, errno, strerror(errno));
   }
}

So it looks like either file descriptor of the timeval struct must have a problem.
From some reading it seems that invalid timeval structs are often caused by one or both
of tv_sec or tv_usec not being set. In the code above we can see that both appear to be
correctly set initially.

From the select() man page I see:

RETURN VALUE
       On success, select() and pselect() return the number of file descriptors contained in
       the three returned descriptor sets (that is, the total number of bits that are set in
       readfds,  writefds,  exceptfds).  The return value may be zero if the timeout expired
       before any file descriptors became ready.

       On error, -1 is returned, and errno is set to indicate the error; the file descriptor
       sets are unmodified, and timeout becomes undefined.

The second paragraph quoted from the man page above would indicate to me that perhaps the
timeout needs to be reset inside the if block. eg:

      if (status < 0 && errno == EINTR) {
         timeout.tv_sec = time;
         timeout.tv_usec = (time-timeout.tv_sec)*1000000.0;
         continue;
      }

Please note that I've only just briefly looked at this and was hoping someone more
familiar with using select() as a way to sleep() might be better able to understand
what is happening.

I wonder also if now that midas requires stricter/newer c++ standards if there maybe
some more straightforward method to sleep that is sufficiently robust and portable.

Thanks,

Nick.

> So I started our DAQ with an updated midas, after ca. 6 months+.

Would be worthwhile mentioning the git commit hash or tag you are using.

> No issues except all FEs complaining about the Alarm ODB structure.
> * I adapted to the new structure ( trigger count & trigger count required )
> * restarted fe's
> * recompiled  
> 
> 18:17:40.015 2025/09/30 [EPICS Frontend,INFO] Fixing ODB "/Alarms/Alarms/logger" 
> struct size mismatch (expected 452, odb size 460)
> 
> 18:17:40.009 2025/09/30 [SC Frontend,INFO] Fixing ODB "/Alarms/Alarms/logger" 
> struct size mismatch (expected 460, odb size 452)

This seems to be https://daq00.triumf.ca/elog-midas/Midas/2980

> how do I get the FEs + ODB back in line here?

Recompile all frontends against new midas.

Nick.

Just to be clear, it seems that your "EPICS Frontend" was either not recompiled against the new midas yet or the old binary is being run, but "SC Frontend" is using the new midas.

> > So I started our DAQ with an updated midas, after ca. 6 months+.
> 
> Would be worthwhile mentioning the git commit hash or tag you are using.
> 
> > No issues except all FEs complaining about the Alarm ODB structure.
> > * I adapted to the new structure ( trigger count & trigger count required )
> > * restarted fe's
> > * recompiled
> > 
> > 18:17:40.015 2025/09/30 [EPICS Frontend,INFO] Fixing ODB "/Alarms/Alarms/logger" 
> > struct size mismatch (expected 452, odb size 460)
> > 
> > 18:17:40.009 2025/09/30 [SC Frontend,INFO] Fixing ODB "/Alarms/Alarms/logger" 
> > struct size mismatch (expected 460, odb size 452)
> 
> This seems to be https://daq00.triumf.ca/elog-midas/Midas/2980
> 
> > how do I get the FEs + ODB back in line here?
> 
> Recompile all frontends against new midas.
> 
> Nick.

Hi,

what you describe is exactly how I normally run mhttpd, mlogger, mserver and some other
custom frontend programs. Eg:

[local:T2KGSC:Running]/>ls /programs/Logger/
Required                        y
Watchdog timeout                100000
Check interval                  180000
Start command                   systemctl --user start mlogger
Auto start                      n
Auto stop                       n
Auto restart                    n
Alarm class                     AlarmNotify
First failed                    0

The only exception is your last point about stdout and stderr
being midas messages. I use journalctl to see these.

Cheers,

Nick.

> I want to control (start / stop / monitor its stdout and stderr) an external process (systemd / EPICS IOC shell script) from within MIDAS.
> 
> In order to make this as convenient as possible for the user, I want the process to behave just like any other MIDAS client:
> - I can start it from the ODB as a program
> - The process gets regularly polled from MIDAS to see whether it is still running
> - I can stop the process from the ODB like any other program
> - Optional, but highly appreciated: Its stdout and stderr should be a MIDAS message.
> 
> Did anyone already solve a similar problem?
> 
> Best regards
> Stefan

Hi,
 
> Nick. Regarding the messages: Zaher showed me that it is possible to simply place
> a custom log file generated by the systemd next to midas.log - then it shows up
> next to the "midas" tab in "Messages".

Interesting. I'm not familiar with that feature. Do you have link to documentation?

> One follow-up question: Is it possible to use the systemctl status for the
> "Running on host" column? Or does this even happen automatically?

On the programs page that column is populated by the odb key /System/Clients/<PID>/Host
so no. However, there is nothing stopping you from writing your own version of
programs.html to show whatever you want. For example I have a custom programs
page the includes columns to enable/disable and to reset watchdog alarms.

Cheers,

Nick.

> I notice the cmake does not actually pass "-std=c++17" to the c++ compiler, and on U-20, it is likely 
> the default c++14 is used. cmake always does the wrong thing and this will need to be fixed later.

Does adding

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

Get it to do the right thing?

Cheers,

Nick..

> I am an applied physicist at Canadian Nuclear Laboratories and am in the process 
> of migrating the full experiment configuration—including the front-end interface—
> of the CRIPT muon tomography detector from a legacy version of MIDAS (SVN Rev. 
> 5238, circa 2012) to a more modern release.
> The current system runs on Scientific Linux 6 and very old hardware. Due to 
> substantial changes in the MIDAS codebase over the years, I have encountered 
> multiple compatibility issues during the migration. I have also attempted to build 
> and run the legacy MIDAS version and the front-end code using GCC 4.8 on a modern 
> Linux system (Ubuntu 24.04), but without success.

I suggest updating the midas version. You should be able to get to at least midas 2024-12-a
without breaking anything.

> Could you please advise on the recommended approach for upgrading or refactoring 
> legacy MIDAS front-end code to the current framework? Any guidance or best 
> practices would be greatly appreciated.

Start here: https://daq00.triumf.ca/MidasWiki/index.php/Changelog
The 2019-06 release was the c -> c++ transition. Read that section carefully.
The 2020-12 update also had a change that you will also likely want to update your FEs for.

You will also likely encounter a quite a few non-midas issues related to the newer compilers.
Updates to your front ends may include things like needing to use "const char*" instead of "char*",
adding extra headers like <cstring> and <cstdlib>, using ctime_r() instead of ctime(), etc

Post back if you have specific questions.

P.S. I'm maintaining a number of midas FEs mostly written around 2007-2009.
These were running on SL5 and SL6 for many years and are now on Alma 9 with
midas 2024-12-a.

> Dear MIDAS experts,
> 
> when I attempted to increase the max number of hotlinks in ODB , defined as 
> 
> #define MAX_OPEN_RECORDS       256           /**< number of open DB records   */
> 
> I started running into an assertion in midas/src/odb.cxx
> 
> https://bitbucket.org/tmidas/midas/src/fa5457b5274a6b42c5ed8b6dea5e3cdd43de38fe/src/odb.cxx#lines-1525 :
> 
>   assert(sizeof(DATABASE_CLIENT) == 2112);
> 
> is it possible that the size of the DATABASE_CLIENT structure should be checked against 64+sizeof(OPEN_RECORD)*MAX_OPEN_RECORDS ?
> - 64 clearly can be expressed in a better maintainable form

Yes, this assert needs to be updated if you increase MAX_OPEN_RECORDS. See 
https://daq00.triumf.ca/MidasWiki/index.php/FAQ#Increasing_Number_of_Hot-links

> UPDATE: similar consideration holds for the size of the DATABLE_HEADER structure, which is also checked against a constant
> 
> https://bitbucket.org/tmidas/midas/src/fa5457b5274a6b42c5ed8b6dea5e3cdd43de38fe/src/odb.cxx#lines-1526

Yes DATABASE_HEADER can also be updated, but the associated assert()s need to be updated too.

FYI I have done both of these things and have attached patches.

Cheers,

Nick.

For the record, the ND280 (T2K near detector) MIDAS GSC was initially set up
with MAX_OPEN_RECORDS = 2560 and MAX_CLIENTS = 128.

In 2023 one fairly simple part of the detector was replaced with several 
other more complex systems (many more midas frontends, equipments, and
variables being logged) so we updated MAX_OPEN_RECORDS = 4096 and 
MAX_CLIENTS = 256.

Nick.

Dear all,

I have problem in event buffer size.

When run MIDAS, I got error "total event size (1307072) larger than buffer size
(1048576)", so I guess that the EVENT_BUFFER_SIZE is small.

I change EVENT_BUFFER_SIZE in midas.h from 0x100000 to 0x200000. After compiling
and run MIDAS, I got other error "Shared memory segment with key 0x4d040761
already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" in
system.C

I check the shmget() function in system.C and it is said that error come from
Shared memory segments larger than 16,773,120 bytes and create teraspace shared
memory segments

Anyone has this problem before?
Thanks for your help

M.T

Dear all,

I have problem in event buffer size.

When run MIDAS, I got error "total event size (1307072) larger than buffer size
(1048576)", so I guess that the EVENT_BUFFER_SIZE is small.

I change EVENT_BUFFER_SIZE in midas.h from 0x100000 to 0x200000. After compiling
and run MIDAS, I got other error "Shared memory segment with key 0x4d040761
already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" in
system.C

I check the shmget() function in system.C and it is said that error come from
Shared memory segments larger than 16,773,120 bytes and create teraspace shared
memory segments

Anyone has this problem before?
Thanks for your help

M.T

I am sorry for my late reply memory in my PC is 16 GB I check the contents of .SHM_TYPE.TXT and it is "POSIXv2_SHM". But there is no buffer sizes in "/Experiment" After run "ipcrm -M 0x4d040761 size0x204a3c", remove .SYSTEM.SHM and run MIDAS again, I still get error "Shared memory segment with key 0x4d040761 already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" M.T

I am sorry for my late reply 

memory in my PC is 16 GB 

I check the contents of .SHM_TYPE.TXT and it is "POSIXv2_SHM". 
But there is no buffer sizes in "/Experiment" 

After run "ipcrm -M 0x4d040761 size0x204a3c", remove .SYSTEM.SHM and run MIDAS again, I still get error "Shared memory segment
with key 0x4d040761 already exists, please remove it manually: ipcrm -M 0x4d040761 size0x204a3c" M.T