Hello, I am new in the forum. We are running an experiment for a week with no
problems. Now we add a detector a we found an error. Even we come back to our
previous configuration the error continues appearing. Please, may someone help
us? You can find the error in the attachment. Thanks!

Dear Midas Team,

I have run into a problem with Midas and was wondering if you could explain what I 
am doing wrong.  I have included a simple demo to illustrate what I am doing and 
can send a small input data file if needed.

WHAT I AM TRYING TO DO:
Every midas event for the DANCE experiment consists of many physics events.  I am 
trying to create a secondary mid file where the event boundaries are now the 
physics events rather than the midas events.  This secondary mid file will be 
analyzed using a second stage midas analyzer.

For the demo, I use the data from EV02 (one of our 15 frontends), which consists of a 
variable number of fixed length structures where each structure contains the data for 
one crystal from the DANCE detector. 
 I treat each crystal as a separate physics event and write it out in the TREK bank, 
which is a demo calculated output bank, as a separate event.   

(The only difference between this demo and our real system is that we would include 
all the crystals from the other frontends that have approximately the same time stamp 
in the output bank.  Thus the output bank would consist of a varing number of 
crystals in one event rather than the fixed one crystal per event used in this demo.)

THE CHANGES TO analyzer.c AND adccalib.c
I loop through the EV02 bank examining each crystal structure in turn.  I calculate 
"calibrated" parameters and put them into an output bank called TREK.  The unusual 
part of this example is that the TREK bank is no longer part of the main list of input 
banks, ana_trigger_bank_list[].   Instead it is now part of a new bank list called 
ana_physics_bank_list[].  See the analyzer.c file for this definition.

In adccalib.c I  create the space for this new bank as follows. 

	EVENT_HEADER 	gPhysicsEventHeaders[ MAX_EVENT_SIZE / sizeof( 
EVENT_HEADER ) ];  
	WORD* 		gPhysicsEventData = ( WORD * )( gPhysicsEventHeaders + 1 );		

In the adc_calib routine I create the bank header as follows.  Note that the serial 
numbers will restart at 0 at the beginning of each midas event.  Should I let the serial 
number increment monotonically until the end of the run?:

	gPhysicsEventHeaders->serial_number = (DWORD) - 1;
	gPhysicsEventHeaders->event_id = 2;
	gPhysicsEventHeaders->trigger_mask = 0;
	gPhysicsEventHeaders->time_stamp = pheader->time_stamp;

In a loop that loops through all the crystals contained in EV02,  I extract each crystal, 
calibrate it, and store it in a TREK structure.  In creating the TREK bank I assume that 
each one will be a separate physics event thus I update the event serial number and 
use bk_init32 to initialize the memory.   

   	for ( short i = 0; i < nItems; i++ )
  	{	++(gPhysicsEventHeaders->serial_number);  	// Update serial number.
  		bk_init32( gPhysicsEventData );		// Initialize storage.
  		bk_create( gPhysicsEventData, "TREK", TID_STRUCT, &trek );
  	
  		trek->one = (double) pev->areahg * 1.0;
  		trek->two = (float) pev->timelo * 1.0;

  		bk_close( gPhysicsEventData, trek+1 );
  		
  		pev++; 					// Loop to next crystal's data. 
	}	

The output bank should consist of multiple events for each individual EV02 midas 
input event. 

 As far as I can tell the code compiles and runs fine, but I get no data in the .mid 
output file except for the ODB. I have a print statement at the beginning of each 
midas event stating how many crystals were found in the EV02 bank.  I also print out 
the calibrated value for each crystal as it is being placed in its own TREK output 
bank.  The data appears correct.

 I cannot place TREK in the input bank the way it normally is done in the examples 
because there is not a one-to-one correspondence between a midas event and a 
true physics event.  Instead one midas event has many physics events.  Thus the 
output bank needs to be in a new memory area so that I can create a custom header 
and increment the serial number properly for each event.  Our follow-on analysis 
using a second Midas analyzer only needs to analyze one physics event at a time 
rather than one Midas event at a time, which is why we are going to all the trouble to 
get this paradigm working.

I include all the code for this very simple example. 

RUNNING THE CODE:
To run the example just use the run01220.mid file I will send:

./analyzer -i run01220.mid.gz -o run01220out.mid -c settings.odb_cfg -n 50

The only thing done by the settings.odb_cfg file is to turn on the TREK output bank.  I 
have verified that the bank is on.

SUMMARY:
I believe that I must not be creating the new TREK output bank correctly so that 
midas understands that the event-by-event calculated physics data should be written 
out event-by-event.  I have pointed out several places in the above discussion where 
I might be making a mistake.

I would like to get both this example running and a similar which create Root trees, 
though the Root trees are of secondary importance.  With this example I can finish 
writing the second stage analyzer and get the DANCE collaboration moving forward 
with their analysis.  Currently, we cannot use this paradigm because I cannot create 
a secondary mid file in our stage one analysis.  I would be very grateful if you could 
take a look at this example and tell me what I am doing incorrectly.

Jan

I would like to know whether all parameters used by the frontend code have to be in the "Experiment/
Run Parameters" section.  This section can become big and difficult to maintain, because it is one single 
big section of experim.h (EXP_PARAM_DEFINED).  I have parameters the various frontends read at the 
beginning of each run, which set the hardware settings of various devices.  I would like to place these in 
a section all their own, organized by device.  Is this doable? 

What is the api call to determine the index of the frontend when specifying the
-i parameter during execution of the frontend? 

Could someone please explain to me how cm_msg, cm_msg1, etc. all work.  The
documentation is very terse.  

I want to setup a fairly significant set of debugging, and error messages for a
new frontend.  I need to get these messages to a logging file.  I also would
like to get the error messages to the user through whatever interface Midas
normally uses for error reporting.  

Jan

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

I'm trying to get a sense of the rate limitations of a python frontend. I 
understand this will vary from system to system.

I adapted two frontends from the example templates, one in C++ and one in python. 
Both simply fill a midas bank with a fixed length array of zeros at a given polled 
rate. However, the C++ frontend is about 100 times faster in both data and event 
rates. This seems slow, even for an interpreted language like python. Furthermore, 
I can effectively increase the maximum rate by concurrently running a second 
python frontend (this is not the case for the C++ frontend). In short, there is 
some limitation with using python here unrelated to hardware.

In my case, poll_func appears to be called at 100Hz at best. What limits the rate 
that poll_func is called in a python frontend? Is there a more appropriate 
solution for increasing the python frontend data/event rate than simply launching 
more frontends?

I've attached my C++ and python frontend files for reference.

Thanks,
Jack

Thank you, this was very helpful.

> First the general advice: if you reduce the "period" of your equipment, then your function will get called more frequently. You can set it to 0 and we'll call it as often as possible. You can set this in the ODB at "/Equipment/Python Data Simulator/Common/Period"

Thanks, I thought that was just for periodic triggering (or at least that's how I've used it in C++ frontends). Changing this allowed me to get past the 100Hz event rate cap I described.

> If that's still not fast enough, then you can return a *list* of events from your readout_func. I've seen real-world cases of 25kHz+ of midas events generated in this fashion.
> 
> 
> However in your case the limitation is likely that you're sending 1.25MB per event and we have a lot of data marshalling to do between the python and C++ layer. In particular it takes 15ms on my machine to just pack the data into a memory buffer (see timeit command below). I am sure there must be a faster way to do this packing, especially in the case where the bank contains a numpy array rather than a python list.
> 
> I'll add it to my to-do list to investigate improving the performance of medium-to-large events in the python code.
> 
> 
> Cheers,
> Ben


> P.S. You may have a bug in your calculations (depending on how you did your testing). In poll_func I think you should be updating the stats every time the function is called, not just the times when you return True.
I had tested the way you described at first, then later changed

> P.P.S. Command I used to test how slow it is to pack the data. One-time setup of creating the buffers, then multiple tests of the pack_into function:
> 
> python -m timeit -s "import struct;import ctypes;arr = [0]*1250001;buf = ctypes.create_string_buffer(10000000);fmt = \">1250000d\"" "struct.pack_into(fmt, buf, *arr)"
> 20 loops, best of 5: 15.3 msec per loop

Thanks for the responses, they were very helpful.

>First the general advice: if you reduce the "period" of your equipment, then your function will get called more frequently. You can set it to 0 and we'll 
call it as often as possible.

Thanks, this solves the event rate limitation I described. I didn't think to change this because the "period" did not affect the observed rate in C (and now 
I know why thanks to Stefan).

A couple more questions:

1. 
For me, 
python -m timeit -s "import struct;import ctypes;arr = [0]*1250001;buf = ctypes.create_string_buffer(10000000);fmt = \">1250000d\"" "struct.pack_into(fmt, 
buf, *arr)"
10 loops, best of 3: 43.7 msec per loop

which suggests my maximum data rate is about 1.25 MB * 1000/43.7 Hz = 23 MB/s (?). But I see data rates up to 60 MB/s with a python frontend. Am I 
misinterpreting the meaning of this result?


2. I can effectively bypass the rate limitations in python by running two concurrent frontends. For example, with one python frontend at best I can generate 
60 MB/s of data (setting "period" to 0 now); but with two frontends I can double this to 120 MB/s. This implies one python frontend is not bottlenecked by 
hardware limitations in my case.

Am I doing something wrong to artificially bottleneck my frontends? Perhaps there's a multi-threading solution I can implement to avoid needing multiple 
frontends?


Thanks,
Jack

If there's some template for writing a client to access event data, that would be 
very useful (and you can probably just ignore the context I gave below in that 
case).


Some context:

Quite a while ago, I wrote the attached "data pipeline" client whose job was to 
listen for events, copy their data, and pipe them to a python script. I believe I 
just stole bits and pieces from mdump.cxx to accomplish this. Later I wrote the 
attached wrapper class "MidasConnector.cpp" and a main.cpp to generalize
data_pipeline.cxx a bit. There were a lot of iterations to the code where I had the 
below problems; so don't take the logic in the attached code as the exact code that 
caused the issues below.

However, I'm unable to resolve a couple issues:

1. If a timeout is set, everything will work until that timeout is reached. Then 
regardless of what kind of logic I tried to implement (retry receiving event, 
disconnect and reconnect client, etc.) the client would refuse to receive more data.

2. When I ctrl-C main, it hangs; this is expected because it's stuck in a while 
loop. But because I can't set a timeout I have to ctrl-C twice; this would 
occasionally corrupt the ODB which was not ideal. I was able to get around this with 
some impractical solution involving ncurses I believe.


Thanks,
Jack

Dear all
I try to save data to an FTP server but don't get any data on the server. Midas does not complain or message any error but also nothing gets saved. Does somebody have experience with this? I use the following settings for the ODB mlogger channel settings: Type: FTP, Filename: server.com, 21, user, pw, ., run%06d.mid, Format: MIDAS, Output: FILE. What would be the Output: FTP setting for? I tried this but it does not work at all. 
Thanks in advance,
Ivo

> > I try to save data to an FTP server but don't get any data on the server. Midas does not complain or message any error but also nothing gets saved. Does somebody have experience with this? I use the following settings for the ODB mlogger channel settings: Type: FTP, Filename: server.com, 21, user, pw, ., run%06d.mid, Format: MIDAS, Output: FILE. What would be the Output: FTP setting for? I tried this but it does not work at all. 
> 
> Hi, Ivo, good to hear from a midas user in these difficult times.
> 
> We do not use FTP at TRIUMF, but Stefan asked us to keep FTP alive and working, so we should be able
> to get you going. I will try to find the FTP instructions for you, I am pretty sure I have them somewhere.
> 
> In the mean time, I am very curious why you are using a FTP to record data, is it some kind
> of data appliance where simplest input for data is FTP? Using NFS does not work or is too hard?
> 
> Also for example at CERN, we write data to Castor and EOS, for this mlogger writes data to local disk,
> then the lazylogger runs a script to move the data to Castor and EOS. The example lazylogger
> scripts for this are in the MIDAS "progs" directory. But maybe you do not have a local disk and this would
> not work for you.
> 
> In other news, I hope to work on mlogger and lazylogger support for cloud storage (swift and s3 apis?),
> would that be useful as replacement for FTP?
> 
> K.O.
>
Good Morning Konstantin

Thanks for the fast reply.  Yes, it is, Midas is one of the things we can at least improve from home. 

Our experiment is planned to measure (soon) at ILL. Now since we don't use the equipment/detector from the 
beamline but our own, all the data from Midas is saved on the local drive. This is fine in the first instance
but then we also need proper backup. Since our experiment is quite small, the easiest solution I came up with
is to copy all of our data to the ILL storage which has enough space and is properly backed up. The ILL data 
storage allows only SFTP connections, nothing else. Since Midas has the FTP feature, having a separate FTP 
logger channel seemed the easiest way to go. 

Thanks for your input, I will look into how to mount SFTP and then this would also be a solution. 

Since ILL only provides access via SFTP and everything else is not existent or blocked (not even ssh is possible),
this is the only thing we can work with by now. 

Best regards,
Ivo

> Logging directly from the midas logger to FTP is a bit cumbersome. In case of delays during login etc. this can throttle the whole DAQ chain. 
> What we use in our lab is to write to local disk, then use the lazylogger (https://midas.triumf.ca/MidasWiki/index.php/Lazylogger) to copy the 
> local files to a remote FTP server. This way we de-couple data taking from backup, making the system much more swift.
> 
> Best,
> Stefan

Yes, see this now too. I will, therefore, try to set up the lazylogger properly. 

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

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

Dear all

To reduce the time needed by Midas between runs, we want to change some of our periodic equipment to multi-threaded slow-control equipment. To do that I wanted to start from 
the slowcont with the multi/hv class driver and the nulldev device driver and null bus driver. The example runs fine as it is on the local midas machine and also on remote 
machines. When adding the DF_MULTITHREAD flag to the device driver list, it does not run anymore on remote machines but aborts with the following assertion:

scfe: /home/neutron/packages/midas/src/midas.cxx:1569: INT cm_get_path(char*, int): Assertion `_path_name.length() > 0' failed.

Running the frontend with GDB and set a breakpoint at the exit leads to the following: 

(gdb) where
#0  0x00007ffff68d599f in raise () from /lib64/libc.so.6
#1  0x00007ffff68bfcf5 in abort () from /lib64/libc.so.6
#2  0x00007ffff68bfbc9 in __assert_fail_base.cold.0 () from /lib64/libc.so.6
#3  0x00007ffff68cde56 in __assert_fail () from /lib64/libc.so.6
#4  0x000000000041efbf in cm_get_path (path=0x7fffffffd060 "P\373g", path_size=256)
    at /home/neutron/packages/midas/src/midas.cxx:1563
#5  cm_get_path (path=path@entry=0x7fffffffd060 "P\373g", path_size=path_size@entry=256)
    at /home/neutron/packages/midas/src/midas.cxx:1563
#6  0x0000000000453dd8 in ss_semaphore_create (name=name@entry=0x7fffffffd2c0 "DD_Input", 
    semaphore_handle=semaphore_handle@entry=0x67f700 <multi_driver+96>)
    at /home/neutron/packages/midas/src/system.cxx:2340
#7  0x0000000000451d25 in device_driver (device_drv=0x67f6a0 <multi_driver>, cmd=<optimized out>)
    at /home/neutron/packages/midas/src/device_driver.cxx:155
#8  0x00000000004175f8 in multi_init(eqpmnt*) ()
#9  0x00000000004185c8 in cd_multi(int, eqpmnt*) ()
#10 0x000000000041c20c in initialize_equipment () at /home/neutron/packages/midas/src/mfe.cxx:827
#11 0x000000000040da60 in main (argc=1, argv=0x7fffffffda48)
    at /home/neutron/packages/midas/src/mfe.cxx:2757

I also tried to use the generic class driver which results in the same. I am not sure if this is a problem of the multi-threaded frontend running on a remote machine or is it 
something of our system which is not properly set up. Anyway I am running out of ideas how to solve this and would appreciate any input. 

Thanks in advance,
Ivo

Thanks you two once again for the very fast answers. I tested the example on the local machine and it works perfectly fine. In the meantime I also created two new drivers for our devices 
and everything works with them, the improvement in time is significant and I will create drivers for all our devices where possible. If they are in a working state I can also provide 
them to add to the Midas drivers. Of course if it would be possible to run the front-end also on our remote machines this would be even better. I am not experienced in any multi-threaded 
programming but if I can provide any help or input, please let me know. 

Have a great weekend,
Ivo

Dear all

We just started our beam time at ILL and just found yesterday that for certain 
settings of our detector the data is not saved into the .mid files. Running "mdump 
-l 10" online we see the data coming in as they should. Nevertheless, if we run 
"mdump -x runXXXXXX.mid" offline, the data file has no events and the banks are 
missing. Any ideas where the data could go lost?

Thanks in advance,
Ivo