Midas: Frequently Asked Questions

Frequently Asked Questions

Midas Code and Libraries

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Data format

Why the CAMAC frontend generate a core dump (linux)?

If you're not using a Linux driver for the CAMAC access, you need to start the CAMAC frontend application through the task launcher first. See dio task or mcnaf task. This task laucher will grant you access permission to the IO port mapped to your CAMAC interface.

Where does Midas log file resides?

As soon as any midas application is started, a file midas.log is produce. The location of this file depends on the setup of the experiment.

if exptab is present and contains the experiment name with the corresponding directory, this is where the file midas.log will reside.
if the midas logger mlogger task is running the midas.log will be in the directory pointed by the "Data Dir" key under the /logger key in the ODB tree.
Otherwise the file midas.log will be created in the current directory in which the Midas application is started.

How do I protected my experiment from being controlled by aliases?

Every experiment may have a dedicated password for accessing the experiment from the web browser. This is setup through the ODBedit program with the command webpass. This will create a Security tree under /Experiment with a new key Web Password with the encrypted word. By default Midas allows Full Read Access to all the Midas Web pages. Only when modification of a Midas field the web password will be requested. The password is stared as a cookie in the target web client for 24 hours See ODB /Experiment Tree.
Other options of protection are described in ODB /Experiment Tree which gives to dedicated hosts access to ODB or dedicated programs.

Can I compose my own experimental web page?

Only under 1.8.3 though. You can create your own html code using your favorite HMTL editor. By including custom Midas Tags, you will have access to any field in the ODB of your experiment as well as the standard button for start/stop and page switch. See mhttpd task , Custom page.

How do I prevent user to modify ODB values while the run is in progress?

By creating the particular /Experiment/Lock when running/ ODB tree, you can include symbolic links to any odb field which needs to be set to Read Only field while the run state is on. See ODB /Experiment Tree.

Is there a way to invoke my own scripts from the web?

Yes, by creating the ODB tree /Script every entry in that tree will be available on the Web status page with the name of the key. Each key entry is then composed with a list of ODB field (or links) starting with the executable command followed by as many arguments as you wish to be passed to the script. See ODB /Script Tree.

I've seen the ODB prompt displaying the run state, how do you do that?

Modify the /System/prompt field. The "S" is the trick.

 Fri> odb -e bnmr1 -h isdaq01
 [host:expt:Stopped]/cd /System/
 [host:expt:Stopped]/System>ls
 Clients
 Client Notify                   0
 Prompt                          [%h:%e:%S]%p
 Tmp
 [host:expt:Stopped]/System
 [host:expt:Stopped]/Systemset prompt [%h:%e:%S]%p>
 [host:expt:Stopped]/System>ls
 Clients
 Client Notify                   0
 Prompt                          [%h:%e:%S]%p>
 Tmp
 [host:expt:Stopped]/System>set Prompt [%h:%e:%s]%p>
 [host:expt:S]/System>set Prompt [%h:%e:%S]%p>
 [host:expt:Stopped]/System>

I've setup the alarm on one parameter in ODB but I can't make it trigger?

The alarm scheme works only under ONLINE. See ODB /RunInfo Tree for Online Mode. This flag may have been turned off due to analysis replay using this ODB. Set this key back to 1 to get the alarm to work again.

How do I extend an array in ODB?

When listing the array from ODB with the -l switch, you get a column indicating the index of the listed array. You can extend the array by setting the array value at the new index. The intermediate indices will be fill with the default value depending on the type of the array. This can easly corrected by using the wildcard to access all or a range of indices.

[local:midas:S]/>mkdir tmp
[local:midas:S]/>cd tmp
[local:midas:S]/tmp>create int number
[local:midas:S]/tmp>create string foo
String length [32]: 
[local:midas:S]/tmp>ls -l
Key name                        Type    #Val  Size  Last Opn Mode Value
---------------------------------------------------------------------------
number                          INT     1     4     >99d 0   RWD  0
foo                             STRING  1     32    1s   0   RWD  
[local:midas:S]/tmp>set number[4] 5
[local:midas:S]/tmp>set foo[3]
[local:midas:S]/tmp>ls -l
Key name                        Type    #Val  Size  Last Opn Mode Value
---------------------------------------------------------------------------
number                          INT     5     4     12s  0   RWD  
                                        [0]             0
                                        [1]             0
                                        [2]             0
                                        [3]             0
                                        [4]             5
foo                             STRING  4     32    2s   0   RWD  
                                        [0]             
                                        [1]             
                                        [2]             
                                        [3]             
[local:midas:S]/tmp>set number[1..3] 9
[local:midas:S]/tmp>set foo[2] "A default string"
[local:midas:S]/tmp>ls -l
Key name                        Type    #Val  Size  Last Opn Mode Value
---------------------------------------------------------------------------
number                          INT     5     4     26s  0   RWD  
                                        [0]             0
                                        [1]             9
                                        [2]             9
                                        [3]             9
                                        [4]             5
foo                             STRING  4     32    3s   0   RWD  
                                        [0]             
                                        [1]             
                                        [2]             A default string
                                        [3]

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