to plot time dependencies of the monitored detector parameters, say, voltages or temperatures,
one needs to convert the coresponging ADC readings into floats.

One could think of two ways of doing that: 

- one can perform the ADC-->T or ADC-->V conversion in the MIDAS frontend, 
  store their [float] values in the data bank, and plot precalculated parameters vs time

- one can also store in the data bank the ADC readings which typically are short's 
  and convert them into floats (V's or T's) at the plotting time 

The first approach doubles the storage space requirements, and I couldn't find the place where 
one would do the conversion, if stored were the 16-bit ADC readings.

I'm sure this issue has been thought about, so what is the "recommended MIDAS way" of performing 
the ADC -> monitored_number conversion when making MIDAS history plots ?

-- many thanks, regards, Pasha

Dear MIDAS developers,

I'm trying to understand handling of the history (slow control) variables in MIDAS,
and it seems that the behavior I'm observing is somewhat counterintuitive. 
Most likely, I just do not understand the implemented logic.

As it it rather difficult to report on the behavior of the interactive program,
I'll describe what I'm doing and illustrate the report with the series of attached 
screenshots showing the history plots and the status of the run control at different 
consecutive points in time.

Starting with the landscape:

- I'm running MIDAS, git commit=30a03c4c (the latest, as of today).

- I have built the midas/examples/slowcont frontend with the following modifications.
  (the diffs are enclosed below):
  
  1) the frequency of the history updates is increased from 60sec/10sec to 6sec/1sec
     and, in hope to have updates continuos, I replaced (RO_RUNNING | RO_TRANSITIONS)
     with RO_ALWAYS.

  2) for convenience of debugging, midas/drivers/nulldrv.cxx is replaced with its clone,
     which instead of returning zeroes in each channel, generates a sine curve:

                  V(t) = 100*sin(t/60)+10*channel

- an active channel in /Logger/History is chosen to be FILE

- /History/LoggerHistoryChannel is also set to FILE 

- I'm running mlogger and modified, as described, 'scfe' frontend from midas/examples/slowcont

- the attached history plots include three (0,4 and 7) HV:MEASURED channels


Now, the observations:

1) the history plots are updated only when a new run starts, no matter how hard
   I'm trying to update them by clicking on various buttons.

   The attached screenshots show the timing sequence of the run control states
   (with the times printed) and the corresponding history plots. 

   The "measured voltages" change only when the next run starts - the voltage graphs 
   break only at the times corresponding to the vertical green lines.

2) No matter for how long I wait within the run, the history updates are not happening.

3) if the time difference between the two run starts gets too large,
   the plotted time dependence starts getting discontinuities

4) finally, if I switch the logging channel from FILE to MIDAS (activate the MIDAS
   channel in /Logger/History and set /History/LoggerHistoryChannel to MIDAS),
   the updates of the history plots simply stop.

MIDAS feels as a great DAQ framework, so I would appreciate any suggestion on 
what I could be doing wrong. I'd also be happy to give a demo in real time 
(via ZOOM/SKYPE etc).

-- much appreciate your time, thanks, regards, Pasha
    
------------------------------------------------------------------------------
diff --git a/examples/slowcont/scfe.cxx b/examples/slowcont/scfe.cxx
index 11f09042..c98d37e8 100644
--- a/examples/slowcont/scfe.cxx
+++ b/examples/slowcont/scfe.cxx
@@ -24,9 +24,10 @@
 #include "mfe.h"
 #include "class/hv.h"
 #include "class/multi.h"
-#include "device/nulldev.h"
 #include "bus/null.h"
 
+#include "nulldev.h"
+
 /*-- Globals -------------------------------------------------------*/
 
 /* The frontend name (client name) as seen by other MIDAS clients   */
@@ -74,11 +75,11 @@ EQUIPMENT equipment[] = {
      0,                         /* event source */
      "FIXED",                   /* format */
      TRUE,                      /* enabled */
-     RO_RUNNING | RO_TRANSITIONS,        /* read when running and on transitions */
-     60000,                     /* read every 60 sec */
+     RO_ALWAYS,        /* read when running and on transitions */
+     6000,                     /* read every 6 sec */
      0,                         /* stop run after this event limit */
      0,                         /* number of sub events */
-     10000,                     /* log history at most every ten seconds */
+     1000,                     /* log history at most every one second */
      "", "", ""} ,
     cd_hv_read,                 /* readout routine */
     cd_hv,                      /* class driver main routine */
@@ -93,8 +94,8 @@ EQUIPMENT equipment[] = {
      0,                         /* event source */
      "FIXED",                   /* format */
      TRUE,                      /* enabled */
-     RO_RUNNING | RO_TRANSITIONS,        /* read when running and on transitions */
-     60000,                     /* read every 60 sec */
+     RO_ALWAYS,        /* read when running and on transitions */
+     6000,                     /* read every 6 sec */
      0,                         /* stop run after this event limit */
      0,                         /* number of sub events */
      1,                         /* log history every event as often as it changes (max 1 Hz) */
------------------------------------------------------------------------------
[test_001]$ diff ../midas/examples/slowcont/nulldev.cxx ../midas/drivers/device/nulldev.cxx 
13d12
< #include <math.h>
150,154c149,150
<    if (channel < info->num_channels) {
<      // *pvalue = info->array[channel];
<      time_t t = time(NULL);;
<      *pvalue = 100*sin(M_PI*t/60)+10*channel;
<    }
---
>    if (channel < info->num_channels)
>       *pvalue = info->array[channel];
------------------------------------------------------------------------------

Hi Sfefan, thanks a lot for taking time to reproduce the issue! 

Here comes the resolution, and of course, it was something deeply trivial :  

the definition of the HV equipment in midas/examples/slowcont/scfe.cxx has 
the history logging time in seconds, however the comment suggests milliseconds (see below), 
and for a few days I believed to the comment (:smile:)

Easy to fix. 

Also, I think that having a sine wave displayed by midas/examples/slowcont/scfe.cxx 
would make this example even more helpful.

-- thanks again, regards, Pasha

--------------------------------------------------------------------------------------------------------
EQUIPMENT equipment[] = {

   {"HV",                       /* equipment name */
    {3, 0,                      /* event ID, trigger mask */
     "SYSTEM",                  /* event buffer */
     EQ_SLOW,                   /* equipment type */
     0,                         /* event source */
     "FIXED",                   /* format */
     TRUE,                      /* enabled */
     RO_RUNNING | RO_TRANSITIONS,        /* read when running and on transitions */
     60000,                     /* read every 60 sec */
     0,                         /* stop run after this event limit */
     0,                         /* number of sub events */
     10000,                     /* log history at most every ten seconds */ // <------------ this is 10^4 seconds, not 10 seconds
     "", "", ""} ,
    cd_hv_read,                 /* readout routine */
    cd_hv,                      /* class driver main routine */
    hv_driver,                  /* device driver list */
    NULL,                       /* init string */
    },


https://bitbucket.org/tmidas/midas/src/7f0147eb7bc7395f262b3ae90dd0d2af0625af39/examples/slowcont/scfe.cxx#lines-81

Dear all,

I have implemented a number of slow control frontends which are directed to update the 
history once in every 10 sec, and they do just that. 

I expected that such frontends would be spending most of the time sleeping and waking up 
once in ten seconds to call their respective drivers and send the data to the server. 

However I observe that each frontend process consumes almost 100% of a single core CPU time 
and the frontend driver is called many times per second. 

Is that the expected behavior ?

So far, I couldn't find the place in the system part of the frontend code (is that the right 
place to look for?) which regulates the frequency of the frontend driver calls, so I'd greatly 
appreciate if someone could point me to that place.

I'm using the following commit:

commit 30a03c4c develop origin/develop Make sure line numbers and sequence lines are aligned.

-- many thanks, regards, Pasha

Hi Stefan, thanks a lot !

I just thought that for the EQ_SLOW type equipment calls to sleep() could be hidden in mfe.cxx 
and handled based on the requested frequency of the history updates.

Doing the same in the user side is straighforward - the important part is to know where the 
responsibility line goes (: smile :) 

-- regards, Pasha

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. 

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

I don't immediately see a reason for saying that if a DB key is older than 10 yrs, it may not be valid.

However, it would be worth learning what was the logic behind choosing 10 yrs as a threshold. 
If 10 is just a more or less arbitrary number, changing 10 --> 100 seems to be the way to go.

-- regards, Pasha 

Dear MIDAS experts, 

- I have a detector configuration with a variable number of hardware components - FPGA's receiving data 
  from the detector. They are described in ODB using a set of keys ranging 
  from "/Detector/FPGAs/FPGA00" .... to "/Detector/FPGAs/FPGA68".
  Each of "FPGAxx" corresponds to an ODB subdirectory containing parameters of a given FPGA. 

  The number of FPGAs in the detector configuration is variable - [independent] commissioning 
  of different detector subsystems involves different number of FPGAs.

  In the beginning of the data taking one needs to loop over all of "FPGAxx", 
  parse the information there and initialize the corresponding FPGAs.

The actual question sounds rather trivial - what is the best way to implement a loop over them? 

- it is certainly possible to have the number of FPGAs introduced as an additional configuration parameter, 
  say, "/Detector/Number_of_FPGAs", and this is what I have resorted to right now.

  However, not only that loooks ugly, but it also opens a way to make a mistake 
  and have the Number_of_FPGAs, introduced separately, different from the actual number 
  of FPGA's in the detector configuration.
 
I therefore wonder if there could be a function, smth like 

    int db_get_n_keys(HNDLE hdb, HNDLE hKeyParent)

returning the number of ODB keys with a common parent, or, to put it simpler, 
a number of ODB entries in a given subdirectory.

And if there were a better solution to the problem I'm dealing with, knowing it might be helpful 
for more than one person - configuring detector readout may require to deal with a variable number 
of very different parameters.

-- many thanks, regards, Pasha

Hi Stefan, Konstantin, 

thanks a lot for your responses - they are very teaching and it is good to have them archived in the forum.
 
Konstantin, as Stefan already noticed, in this particular case the race condition is not really a concern.

Stefan, the ChatGPT-generated code snippet is awesome! (teach a man how to fish ...)

-- regards, Pasha

> 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

Konstantin is right: KEY.num_values is not the same as the number of subkeys (should it be ?)
For those looking for an example in the future, I attach a working piece of code converted 
from the ChatGPT example, together with its printout.

-- regards, Pasha

Dear MIDAS experts,

I gave a try to the MIDAS python interface and ran all tests available in midas/python/tests.
Two Int64 tests from test_odb.py had failed (see below), everthong else - succeeded

I'm using a ~ 2.5 weeks-old commit and python 3.9 on SL7 Linux platform.

commit c19b4e696400ee437d8790b7d3819051f66da62d (HEAD -> develop, origin/develop, origin/HEAD)
Author: Zaher Salman <zaher.salman@gmail.com>
Date:   Sun Jan 14 13:18:48 2024 +0100

The symptoms are consistent with a string --> int64 conversion not happening 
where it is needed. 

Perhaps the issue have already been fixed? 

-- many thanks, regards, Pasha
-------------------------------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 178, in testInt64
    self.set_and_readback_from_parent_dir("/pytest", "int64_2", [123, 40000000000000000], midas.TID_INT64, True)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 130, in set_and_readback_from_parent_dir
    self.validate_readback(value, retval[key_name], expected_key_type)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 87, in validate_readback
    self.assert_equal(val, retval[i], expected_key_type)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 60, in assert_equal
    self.assertEqual(val1, val2)
AssertionError: 123 != '123'

with the test on line 178 commented out, the test on the next line fails in a similar way:
        
Traceback (most recent call last):
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 179, in testInt64
    self.set_and_readback_from_parent_dir("/pytest", "int64_2", 37, midas.TID_INT64, True)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 130, in set_and_readback_from_parent_dir
    self.validate_readback(value, retval[key_name], expected_key_type)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 102, in validate_readback
    self.assert_equal(value, retval, expected_key_type)
  File "/home/mu2etrk/test_stand/pasha_020/midas/python/tests/test_odb.py", line 60, in assert_equal
    self.assertEqual(val1, val2)
AssertionError: 37 != '37'
---------------------------------------------------------------------------

Dear MIDAS experts,

I have multiple daq nodes with two data receiving FPGAs on the PCIe bus each. 
The FPGAs come under the names of DTC0 and DTC1. Both FPGAs are managed by the same slow control frontend. 
To distinguish FPGAs of different nodes from each other, I included the hostname to the equipment name, 
so for node=mu2edaq09 the FPGA names are 'mu2edaq09:DTC0' and 'mu2edaq09:DTC1'. 

The history system didn't like the names, complaining that 

21:26:06.334 2024/02/05 [Logger,ERROR] [mlogger.cxx:5142:open_history,ERROR] Equipment name 'mu2edaq09:DTC1' 
contains characters ':', this may break the history system

So the question is : what are the safe equipment/driver naming rules and what characters 
are not allowed in them? - I think this is worth documenting, and the current MIDAS docs at 
 
https://daq00.triumf.ca/MidasWiki/index.php/Equipment_List_Parameters#Equipment_Name 

don't say much about it.

-- many thanks, regards, Pasha

> For ODB keys of type TID_KEY, the value num_values IS the number of subkeys. 

this logic makes sense, however it doesn't seem to be consistent with the printout of the test example
at the end of https://daq00.triumf.ca/elog-midas/Midas/240203_095803/a.cc . The printout reports 

key.num_values = 1, but the actual number of subkeys = 6, and all subkeys being of TID_KEY type

I'm certain that the ODB subtree in question was not accessed concurrently during the test.

-- regards, Pasha

> > Hmm... is there any use case where you want to know the number of directory entries, but you will not iterate 
> > over them later?
> 
> I agree. 

here comes the use case: 

I have a slow control frontend which monitors several DAQ components - software processes. 
The components are listed in the system configuration stored in ODB, a subkey per component.

Each component has its own driver, so the length of the driver list, defined by the number of components, 
needs to be determined at run time.

I calculate the number of components by iterating over the list of component subkeys in the system configuration, 
allocate space for the driver list, and store the pointer to the driver list in the equipment record.

The approach works, but it does require pre-calculating the number of subkeys of a given key.

-- regards, Pasha

Dear MIDAS Experts,

I'm having an odd problem when trying to display an integer stored in ODB on a custom 
web page:  the hex specifier, "%x", displays integers as if it were "%d" .

- attachment 1 shows the layout and the contents of the ODB sub-tree in question
- attachment 2 shows the web page as it is displayed
- attachment 3 shows the snippet of html/js producing the web page

I bet I'm missing smth trivial - an advice is greatly appreciated! 

Also, is there an equivalent of a "0x%04x" specifier to have the output formatted 
into a fixed length string ?  

-- thanks, regards, Pasha  

Hi Stefan (and Ben),

thanks for reacting so promptly - your commits on Bitbucket fixed the problem.

For those of us who knows little about how the web browsers work: 

- picking up the fix required flushing the cache of the MIDAS client web browser - apparently the web browser 
  I'm using - Firefox 115.6 - cached the old version of midas.js but wouldn't report it cached and wouldn't load 
  the updated file on its own.

-- thanks again, regards, Pasha

Dear all, 

this posting results from the Fermilab move to a new packaging/build system called spack 
which doesn't allow to use the MIDAS install procedure described at

https://daq00.triumf.ca/MidasWiki/index.php/Quickstart_Linux#MIDAS_Package_Installation

as is. Spack specifics aside, building MIDAS under spack took  
a) adding cmake install for three directories: drivers, resources, and python/midas, 
b) adding one more include file - include/tinyexpr.h - to the list of includes installed by cmake.

With those changes I was able to point MIDASSYS to the spack install area and successfully run mhttpd, 
build experiment-specific C++ frontends and drivers, use experiment-specific python frontends etc. 
I'm not using anything from MIDAS submodules though.

I'm wondering what the experts would think about accepting the changes above to the main tree. 

Installation procedures and changed to cmake files are always a sensitive area with a lot of boundary 
constraints coming from the existing use patterns, and even a minor change could have unexpected consequences
So I wouldn't be surprised if the fairly minor changes outlined above had side effects.

The patch file is attached for consideration.

-- regards, Pasha

Hi All,

I have found a weird one:

The following code executes on the frontend machine in the
frontend_exit() routine, and connects to the odb running on
another separate machine:
...
     cm_msg(MINFO,__func__, "line %d", __LINE__);

     cm_get_experiment_database(&hdb, NULL);

     cm_msg(MINFO,__func__, "line %d", __LINE__);
     status = db_find_key(hdb, 0, "/Experiment/Run Parameters", &hkey);
     cm_msg(MINFO,__func__, "line %d, hkey=%d, status=%d",
            __LINE__, hkey, status);
     checkstat("db_find_key returned status %d", status);
     cm_msg(MINFO,__func__, "line %d", __LINE__);
     status = db_close_record(hdb, hkey);

     /* NOTREACHED!! the above call to db_close_record
        doesn't return!
      */
     cm_msg(MINFO,__func__, "line %d, status=%d", __LINE__, status);
     checkstat("db_close_record returned status %d", status);

checkstat is a macro that does the following:
#define checkstat(format, arg...)\
do{ if(status != DB_SUCCESS) {\
cm_msg(MERROR, __func__, format, ## arg);\
return FE_ERR_ODB;}}while(0)

The key exists, and the status of the search is 1
(i.e., DB_SUCCESS) and rest of the code tries to run.  What gets
really weird is that the db_close_record _doesn't_ _return_.
The code following the NOTREACHED comment just doesn't get
called.  I get the message from the __LINE__ just in front
of the call, but not the message afterwards (cm_msg and printf 
were tried).  Somehow db_close_record is causing a non-local 
exit or signal or something. No error message is printed and the 
frontend continues to exit with exit code 0.  But, since the rest
of my frontend_exit/odb closing doesn't happen, the odb is left in
a lost state requiring a cleanup.  If I comment out the calls to 
db_close_record, the rest of my frontend_exit runs normally 
and the cm_disconnect_experiment() in mfe.c eventually closes my 
open records correctly (I expect, anyway) and this is the present 
workaround i am using.  The terror i have is that several of my 
hotlinked callback routines will call the close_record routine 
when resetting illegal values.  No end of hilarity will result there...

I was using the same code in the frontend under 1.9.2 and
have only recently upgraded to 1.9.3-? tarball from PAA and 
there were no problems using the 1.9.2 code: this is a 1.9.3
issue.

I have localized the weirdness to what I think is the RPC interface.
Running the nullfrontend (no camac access) on the same machine as 
hosts the ODB I can make the problem appear and disappear in the 
following way:
(odb is local on machine ``monet'')

nullfe -h monet -e acqmonad     : db_close_record will get lost

nullfe -e acqmonad              : db_close_record works as expected.

I've tried also with the patch for the 256 byte odb string bug since
many of the open records have strings of that length, but that isn't
it. The only substancial looking change to mserver from 1.9.2 to 1.9.3
is the SIGPIPE ignore and that doesn't look like a good candidate either.
Can this be that some of the 
   #IFDEF LOCAL_ROUTINES
that got moved about in odb.c and others
are causing the remote call to get confused?

Clearly the answer is to just use stable and happy 1.9.2, but the 
people for whom I am working now really want to use ROOT for
an analyzer...


cheers,
.p.

Paul Knowles.                   phone: 41 26 300 90 64
email: Paul.Knowles@unifr.ch      Fax: 41 26 300 97 47
finger me at pexppc33.unifr.ch for more contact information