[Halld-level1] Data stream scalers, summary of the meeting

[Alexander Somov]

Hi Dave,

We are planning to have two types of scalers:

1. Scalers accessable from the boards registers. These scalers
can be read out by a monitoring process running on the ROC. They
are accessable even when the trigger (DAQ) get's stuck...
We have these scalers implemented on the firmware level and
are currently working on the client-server implementation
(I already have a prototype). During the data taking, we
are not planning to use these scalers all the time. It would
make sense to monitor the detector performance (occupancies, energy
flow, ...) using the data stream scalers, i.e., those written to
the data (evio) file.

2. Scalers going to the data stream; we were discussing them
in the previous mails.


Cheers,
        Sasha




On Mon, 23 Jan 2012, David Lawrence wrote:

>
> Hi Sasha,
>
>   Are they counting even when the DAQ system is not currently taking
> data? I would think we would want an out-of-band way of getting at the
> scalers. That way, we can display them at any time (e.g. while tuning
> the beam in between runs). Maybe you mentioned something about this
> before...?
>
> -Dave
>
> On 1/23/12 1:25 PM, Alexander Somov wrote:
>> Hi Elton,
>>
>> A good point.
>>
>> You don't need to disentangle the whole events.
>> Scalers will have a tag in the fadc event block;
>> one will need to search for the corresponding tags
>> only; should be straight forward.
>>
>> Cheers,
>>          Sasha
>>
>>
>>
>> On Mon, 23 Jan 2012, Elton Smith wrote:
>>
>>> Hi Sasha,
>>>
>>> Thanks for the summary. In mode a) can easily scan through a file and
>>> pick out the events with scalers (without disentangling the whole event)?
>>>
>>> Elton Smith
>>> Jefferson Lab MS 12H5
>>> 12000 Jefferson Ave
>>> Suite #16
>>> Newport News, VA 23606
>>> (757) 269-7625
>>> (757) 269-6331 fax
>>>
>>>
>>> On 1/23/12 9:10 AM, Alexander Somov wrote:
>>>> Hi,
>>>>
>>>> I brief summary of the data stream scaler
>>>> implementation  discussion last Friday
>>>> (Jan 20th, 2012):
>>>>
>>>> 1. Scalers will be integrated into the data readout
>>>> block of each FADC; they will be readout using DMA.
>>>>
>>>> 2. There are two ways of the implementation:
>>>>      a) scalers will be added to the last event in
>>>>         the block. A user needs to specify the block
>>>>         prescaling factor, i.e., the number of blocks
>>>>         after which the scalers should be added
>>>>         (for instance, add scalers in each 10000's readout
>>>>         blocks).
>>>>      b) Scaler readout will be handled by the special
>>>>         trigger type generated by the TS (the trig2 line
>>>>         going from the TI to the fadc can, for instance, be
>>>>         used for the scaler trigger distribution). Similar
>>>>         to a), scalers will be added to the readout block.
>>>>         Implementing this mode will require more efforts.
>>>>
>>>> 3. Edd and Bryan will start implementing mode a).
>>>>
>>>>
>>>> Cheers,
>>>>          Alex
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