Since the column on the main midas status page with fraction of analyzed events is 
barely used, I decided to drop it. Anyhow it does not make sense for all slow 
control events. If this feature is required in some experiment, I propose to move it 
into a custom page and calculate this ratio in JavaScript, where one has much more 
flexibility. 

This modification frees up more space on the status page for the "Status" column, where 
front-end programs can report errors etc.

The mhttpd program shows some standard buttons in the top row for 
starting/stopping runs, accessing the ODB, Alarms, etc. Since not all experiments 
make use of all buttons, they have been customized. By default mhttpd creates 
following entry in the ODB:

/Experiment/Menu Buttons = Start, ODB, Messages, ELog, Alarms, Programs, History, 
Config, Help

Which is the standard set (except the old CNAF). People can customize this now by 
removing unnecessary buttons or by changing their order. The "Start" entry above 
actually causes the whole set of Start/Stop/Pause/Resume buttons to appear, 
depending on the current run state. 

Hi Jimmy,

ok, now I understand. Well, I don't see your problem. I just tried with the 
current SVN 
version to start

midas/examples/experiment/frontend
midas/examples/slowcont/scfe

in the same directory (without "-h localhost") and it works just fine (see 
attachemnt). I even started them from the same directory. Yes there are *.SHM 
files and they correspond to shared memory, but both front-ends use this shared 
memory together (that's why it's called 'shared').

Your error message 'Semaphore already present' is strange. The string is not 
contained in any midas program, so it must come from somewhere else. Do you 
maybe try to access the same hardware with the two front-end programs?

I would propose you do the following: Use the two front-ends from the 
distribution (see above). They do not access any hardware. See if you can run 
them with the current SVN version of midas. If not, report back to me.

Best regards,

  Stefan


> Dear Stefan,
> 
> Thanks for the reply. I have tried your patch and it didn't solve my problem. 
Maybe I 
> have not written my question clearly. The two frontends could run on the same 
computer 
> if I use the remote method, i.e. by setting up the mserver and connect to the 
> experiment by specifying "-h localhost", also the frontend programs need to be 
put in 
> different directory. What I want to know is whether I can simply start 
multiple 
> frontends in the same directory without setting up the mserver etc. I noticed 
that 
> there are several *.SHM files, I'm not familiar with semaphore, but I guess 
they are 
> the key to the problem. Please correct me if I misunderstood something.
> 
> Best Regards,
> Jimmy
> 
> 
> > > Dear All,
> > > 
> > > I want to run two frontend programs (one for trigger and one for slow 
control)
> > > concurrently on the same computer, but I failed. The second frontend said: 
> > > 
> > > Semaphore already present
> > >  There is another process using the semaphore.
> > >  Or a process using the semaphore exited abnormally.
> > >  In That case try to manually release the semaphore with:
> > >    ipcrm sem XXX.
> > > 
> > > The two frontends are connected to the same experiment. Is there any way I 
can
> > > overcome this problem?
> > 
> > That might be related to the RPC mutex, which gets created system wide now. 
I 
> > modified this in midas.c rev. 4628, so there will be one mutex per process. 
Can you 
> > try that temporary patch and tell me if it works for you?

/Experiment/Menu Buttons = Start, ODB, Messages, ELog, Alarms, Programs, History, MSCB, Config, Help

[local:MEG:R]/MSCB>ls -r
MSCB
    Submaster
        mscb004
            Pwd                 xxxxx
            Comment             BTS
            Address             1
        mscb034
            Pwd                 xxxxx
            Comment             XEC HV & LED
            Address
                                0
                                1
                                2

/Equipment/<name>/Settings/Devices/Input/Device

/Equipment/<name>/Settings/Devices/<name>/MSCB Device

> > The custom and alias links in the standard midas status page were shown as HTML 
> > links so far. If there are many links with names having spaces in their names, 
> > it's a bit hard to distinguish between them. Therefore, they are packed now into 
> > individual buttons (see attachment) starting from SVN revision 4633 on. This makes 
> > also the look more homogeneous. If there is any problem with that, please report.
> 
> Would you consider using a different colour for the alias buttons (or background
> colour)? At present it's hard to know whether a button is an alias link, a custom page
> link or a user-button especially if you are not familiar with the button layout. 

Ok, I changed the background colors for the button rows. There are now four different 
colors: Main menu buttons, Scripts, Manually triggered events, Alias & Custom pages. Hope 
this is ok. Of course one could have each button in a different color, but then it gets 
complicated... In that case I would recommend to make a dedicated custom page with all these 
buttons, which you can then tailor exactly to your needs.

> The mhttpd program shows some standard buttons in the top row for 
> starting/stopping runs, accessing the ODB, Alarms, etc. Since not all experiments 
> make use of all buttons, they have been customized. By default mhttpd creates 
> following entry in the ODB:
> 
> /Experiment/Menu Buttons = Start, ODB, Messages, ELog, Alarms, Programs, History, 
> Config, Help
> 
> Which is the standard set (except the old CNAF). People can customize this now by 
> removing unnecessary buttons or by changing their order. The "Start" entry above 
> actually causes the whole set of Start/Stop/Pause/Resume buttons to appear, 
> depending on the current run state. 

Upon request the set of Menu Buttons has been extended to

/Experiment/Menu Buttons = Start, Pause, ODB, Messages, ELog, Alarms, Programs, 
History, Config, Help

by adding the additional "Pause" string. Without "Pause" being present in the list of 
menu buttons, the run cannot be paused/resumed, but only started/stopped. This is 
required by some experiments. If "/Experiment/Menu Buttons" is not present in the ODB, 
it gets created with the above default. If it is there from the previous update, the 
"Pause" string might be missing, so it must be added by hand if required. The 
modification is committed as revision #4684.

> I use fedora 12 and midas 4680. there is problem to start run when the frontend
> application runs fine. 

I don't know exactly what is wrong, but I would check following things:

- does your feTCPPacketReceiver die during the start-of-run? Maybe you do some segfault 
int he begin-of-run routine. Can you STOP a run?

- is there any network problem due to your two cards? When you try to stop your fe from 
odbedit with

# odbedit -c "shutdown feTCPPacketReceiver"

do you then get the same error? The shutdown functionality uses the same RPC channel as 
the start/stop run. Some people had firewall problems, on both sides (host AND client), 
so make sure all firewalls are disabled.

- if you disable one network card, do you still get the same problem?

> > Hi, there. I have not recently run mserver through inetd, and we usually do not do
> > that at TRIUMF. We do this:
> > 
> > a) on the main computer: start mserver: "mserver -p 7070 -D" (note - use non-default
> > port - can use different ports for different experiments)
> > b) on remote computer: "odbedit -h main:7070" ("main" is the hostname of your main
> > computer). Use same "-h" switch for all other programs, including the frontends.
> > 
> > This works well when all computers are on the same network, but if you have some
> > midas clients running on private networks you may get into trouble when they try to
> > connect to each other and fail because network routing is funny.
> 
> Hi K.O.,
> 
> Thanks for your reply. I have tried your way but I got the same error: 
> 
> [midas.c:8623:rpc_server_connect,ERROR] mserver subprocess could not be started 
> (check path)
> 
> My front-end and back-end computers are on the same network connected by a router. I 
> have allowed port 7070 in the firewall and done the port forwarding in the router (for 
> connecting from outside the network). From the error message it seems that some 
> processes can not be started automatically. Could it be related to some security 
> settings such as the SELinux?

The way connections work under Midas is there is a callback scheme. The client starts 
mserver on the back-end, then the back-end connects back to the front-end on three 
different ports. These ports are assigned dynamically by the operating system and are 
typically in the range 40000-60000. So you also have to allow the reverse connection on 
your firewalls.

> It looks like some example drivers in .../drivers/class want to link against YBOS libraries. 
> This fails because ybos.o is missing from the MIDAS library.

I fixed the class drivers in meantime (SVN 4814).

There is however another problem: The lazylogger needs YBOS support compiled in if the FTP transfer mode is used. 
At PSI we are stuck at the moment to FTP, so we still need YBOS there (although none of the data is in YBOS format). 
Maybe there is a chance that this will be fixed some time and we can get rid of YBOS.

Just some idea:

The ultimate solution to that would be to do that completely JavaScript driven. You load ONCE the list of all 
variables into a local array, then sort this into your history panel LOCALLY. When I did the original mhttpd 
history config page, there was not much JavaScript around, but today this would be the ultimate option. It 
even supports drag-and-drop. So let's keep that in mind for the future.

- Stefan

> We had javascript ODBGet() and ODBSet() functions for some time now, permitting 
implementation of 
> "page-reload-free" "self-updating" web pages. I finally got around to put all 
the javascript bits together 
> to actually implement such a page.

Unfortunately the page has tons of JavaScript errors, probably happened during 
copy-and-paste to elog. Note that 
such files are better places as attachment. I attached a screen dump from the JS 
debugger inside Chrome which I 
use normally to debug JS.

Please find attached another example of a JavaScript (JS) page using the 
ODBGet/Set functions. 

In contrast to the previous posting, the page is not constructed via the 
document.writeln() function, but written directly in HTML and modified through the 
"innerHTML = ..." functionality. 

It is a control page for our beamline, which gets updated in the background. In 
addition, the user can set the beamline to three predefined settings which are 
stored in an array at the top of the page. As an little extra there is a progress 
bar, which is updated locally via JS since changing the beamline takes a while. 
The progress bar is implemented as a table with variable width, and dynamically 
updated by the JS program. The second attachment is a screen dump from such a 
switching process. Since only values in the ODB are changed, you can try it 
yourself without actually modifying a PSI beam line ;-)

> The attached errors all seem to be from cut-and-paste line breaks in the long "document.writeln()" statements. 
> When the page runs, there are no errors from Firefox and Safari.

Then it would be good if you re-submit the file as an attachment so that other people can use it.

> This example uses "document.writeln()" because the number of PostAmp devices displayed in the table is not 
> known in advance and is potentially read from ODB at page load time.

This was not a criticism but just to show that there are different ways of constructing such a page, depending on the 
needs. So people have the choice. Anyhow I think it's very good to have some working examples for people to start 
with.

> very recent mhttpd mangles spaces in URL encoding-decoding and I cannot create or delete entries in for 
> example "/experiment/edit on start". For example attempt to delete "/experiment/Pedestals Run" 
> produces:
> <h1>Cannot find key Experiment/edit%20on%20start/Pedestals run</h1>
> (notice "%20" instead of spaces. further navigation sometimes replaces the "%" sign with "%25" making it 
> even more mangled)
> 
> this used to work. looks like a call to URL unmangling went missing somewhere.
> K.O.

Thanks for reporting. Fixed in SVN revision 4882. Actually I outcommented the fix some time ago and forgot to 
put it back. Now I hope that this does not blow anything else...

- Stefan

midas\mscb\embedded
  \include                <- place for framework include file mscbemb.h
  \lib                    <- precompiled TCP/IP library for SCS-260 submaster
  \src                    <- framework sources mscbmain.c and mscbutil.c
  \<project1>             <- separate folder for project1
      config.h            <- config file for project1
  \<project2>             <- separate folder for project2
      config.h            <- config file for project2
  ...
  \experiment
     \<experiment1>
     \<experiment2>

• The framework files mscbmain.c mscbutil.c and mscbemb.h have moved and therefore they have to be re-added to the projects in the Keil MicroVision Development Environment.
  
• The name of the device should not be defined under compiler settings (Project Options/C51/Preprocessor Symbols), but put directly into the config.h file associated with the project.
  
• The include paths in the compile have to be changed and point to \midas\mscb\embedded\include
  
• The file config.h has to be copied from a similar project and adjusted to fit the new project.
  

> uhm, mine might be completely unrelated to this, but it just so happened that the rev.
> 4936 was one that was used in a recent experiment, in which there was complaints about
> the responsiveness of the history plots. The history plots would take up to 30 seconds
> to respond, if the run was about 30-40 minutes old. When the run is about  < 10 minutes
> old , the history plot was responsive to within 1-2 seconds.

Ah, that rings a bell. How big are your history files on disk? How much RAM do you have?

What I see in our experiment is that linux buffers everything I write to disk in a cache 
located in RAM. But this cache is limited, so after a certain time it's overwritten. Now 
this is handled by the OS, the application (mlogger in this case) has no influence on it. 
Let's say you write 5 MB/minute of history, and your cache is 50 MB large. Then after 10 
minutes you can still read the history data from the RAM cache which is ~10x faster than 
your disk. But your older history data (30-40 min) is flushed out of the cache and has to be 
re-read from disk. A typical symptom of this is that the first time you display this it 
takes maybe 30 seconds, but if you do a "reload" of your page it goes much faster. In that 
case the contents is cached again in RAM. If you observe this, you can almost be certain 
that you see th "too small RAM cache" problem. In that case just add RAM and things should 
run better (I use 16 GByte in my machine).

Best regards,

  Stefan

> Reading an FADC buffer often needs large buffer size, especially while several
> FADCs work together. I want to know how large a bank32 can support.

The "32" in bank32 means 32-bits, so the bank holds 2^32=4 GBytes, hope that is enough for your ADC. 
The "normal" bank has only a 16-bit header, so it can hold only 64 kBytes. But for small banks, the overhead 
is therefore smaller.