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. 

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?

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?

Dear Stefan,

I followed your suggestion to try the sample front-ends from the distribution and 
they work fine. They also work fine with any one of my front-ends. Only my two 
front-ends cannot run concurrently in the same directory. I later found that the 
problem is in the CAEN HV wrapper library. The problem arises when the front-ends 
are both linked to that library and it is solved now.

Thanks & Best Regards,
Jimmy


> 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. 

> > 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.

Hi,

On a custom web page, can a "filled" area be made to flash (i.e. cycle between 
two colours)? This area would have to update faster than the whole page update.
 
I have a custom page representing a gas system, and the users
want the heaters to flash when they are on, as is done in their EPICS page.

Thanks,
Suzannah 

Notes on the implementation of the MIDAS alarm system.

Alarms are checked inside alarm.c::al_check(). This function is called by
cm_yield() every 10 seconds and by rpc_server_thread(), also every 10 seconds.

For remote midas clients, their al_check() issues an RPC_AL_CHECK RPC call into
the mserver, where rpc_server_dispatch() calls the local al_check().

As result, all alarm checks run inside a process directly attached to the local
midas shared memory (inside a local client or inside an mserver process for a
remote client).

Each and every midas client runs the alarm checks. To prevent race conditions
between different midas clients, access to al_check() is serialized using the
ALARM semaphore.

Inside al_check(), alarms are triggered using al_trigger_alarm(), which in turn
calls al_trigger_class(). Inside al_trigger_class(), the alarm is recorded into
an elog or into midas.log using cm_msg(MTALK).

Special note should be made of the ODB setting "/Alarm/Classes/xxx/System
message interval", which has a surprising effect - after an alarm is recorded
into system messages (using cm_msg(MTALK)), no record is made of any subsequent
alarms until the time interval set by this variable elapses. With default value
of 60 seconds, after one alarm, no more alarms are recorded for 60 seconds.
Also, because all the alarms are checked at the same time, only the first
triggered alarm will be recorded.

As of alarm.c rev 4683, "System message interval" set to 0 ensures that every
alarm is recorded into the midas log file. (In previous revisions, this setting
may still miss some alarms).

There are 3 types of alarms:

1) "program not running" alarms.

These alarms are enabled in ODB by setting "/Programs/ppp/Alarm class". Each
time al_check() runs, every program listed in "/Programs" is tested using
"cm_exist()" and if the program is not running, the time of first failure is
remembered in "/Programs/ppp/First failed".

If the program has not been running for longer than the time set in ODB
"/Programs/ppp/Check interval", an alarm is triggered (if enabled by
"/Programs/ppp/Alarm class" and the program is restarted (if enabled by
"/Programs/ppp/Auto restart").

The "not running" condition is tested every 10 seconds (each time al_check() is
called), but the frequency of "program not running" alarms can be reduced by
increasing the value of "/Alarms/Alarms/ppp/Check interval" (default value 60
seconds). This can be useful if "System message interval" is set to zero.

2) "evaluated" alarms
3) "periodic" alarms

There is nothing surprising in these alarms. Each alarm is checked with a time
period set by "/Alarm/xxx/Check interval". The value of an evaluated alarm is
computed using al_evaluate_condition().

K.O.

> 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 want to let the run stop and start periodically. But I looked through the ODB
and didn't find anything may help. I also checked the FAQ online and didn't find
answer either. Who can help me? Thank you.

Hi Exaos,

This may help: https://ladd00.triumf.ca/elog/Midas/645

You need to set the following keys:
/Logger/Run duration
/Logger/Auto restart
/Logger/Auto restart delay

Regards,
Jimmy


> I want to let the run stop and start periodically. But I looked through the ODB
> and didn't find anything may help. I also checked the FAQ online and didn't find
> answer either. Who can help me? Thank you.

Dear All,

After clicking the "Start" button, there is a page for the operator to change some 
ODB values. I have created "/Experiment/Edit on start" and added some links there. 
If the link is pointed to a boolean type key, a check box will appear in the 
"Start" page, which is great. But how about if I want to have some radio buttons 
or pull-down menus for the operator to select among different calibration sources 
or running modes?

Thanks,

Jimmy

do: svn co svn+ssh://svn@savannah.psi.ch/afs/psi.ch/project/meg/svn/midas/trunk
midas
shows: ssh: connect to host savannah.psi.ch port 22: Connection timed out
svn: Connection closed unexpectedly

> do: svn co svn+ssh://svn@savannah.psi.ch/afs/psi.ch/project/meg/svn/midas/trunk
> midas
> shows: ssh: connect to host savannah.psi.ch port 22: Connection timed out
> svn: Connection closed unexpectedly

sorry, my side network problem.
N.

Dear experts,

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


# odbedit -c start


Starting run #18
[midas.c:8423:rpc_client_connect,ERROR] timeout on receive remote computer info: 
[midas.c:3659:cm_transition,ERROR] cannot connect to client
"feTPCPacketReceiver" on host tpcdaq0, port 36663, status 503
[midas.c:8423:rpc_client_connect,ERROR] timeout on receive remote computer info: 
[midas.c:4880:cm_shutdown,ERROR] Cannot connect to client 'frontend' on host
'hostname', port 36663
[midas.c:4883:cm_shutdown,ERROR] Killing and Deleting client
'feTPCPacketReceiver' pid 24516
[midas.c:3857:cm_transition,ERROR] Could not start a run: cm_transition() status
503, message 'Cannot connect to client 'frontend''
Run #18 start aborted
Error: Cannot connect to client 'frontend'

11:03:42 [Logger,INFO] Deleting previous file "/home/daq/Run/online/run00018.mid"

11:03:42 [Logger,INFO] Client 'feTPCPacketReceiver' on buffer 'SYSMSG' removed
by cm_watchdog because client pid 24516 does not exist

11:03:42 [Logger,ERROR] [system.c:563:ss_shm_close,ERROR]
shmctl(shmid=7274511,IPC_RMID) failed, errno 1 (Operation not permitted)

11:03:42 [ODBEdit,INFO] Run #18 start aborted
==========================================================================

there are several ethernet cards on the host machine. eth0 connect the host
machine to the gateway machine and the front end application listen to eth1 for
the incoming data packets:

eth0      Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx  
          inet addr:10.0.1.1  Bcast:10.0.1.63  Mask:255.255.255.0
          inet6 addr: fe80::f6ce:46ff:fe99:709b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:470870 errors:0 dropped:0 overruns:0 frame:0
          TX packets:515987 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:345000246 (329.0 MiB)  TX bytes:377269124 (359.7 MiB)
          Interrupt:17 

eth1      Link encap:Ethernet  HWaddr xx:xx:xx:xx:xx:xx   
          inet addr:10.0.1.2  Bcast:10.255.255.255  Mask:255.0.0.0
          inet6 addr: fe80::226:55ff:fed6:56a9/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:1836 (1.7 KiB)
          Memory:ec180000-ec1a0000 


thanks for hints

> 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?