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Hi All,<br>
<br>
I spoke with Beni a little about this this morning since I am
currently<br>
working on the code that parses this for the online monitoring and<br>
the offline. I have not been involved in any other discussions, but
here<br>
are some thoughts based on what I've seen in the F250ADC formats<br>
and my discussion with Beni:<br>
<br>
1.) It is not possible to fit both the sum and the pulse time into a
single<br>
32-bit word. The word must have at least 12 bits of info to define
the<br>
data type and channel number leaving only 20 bits for payload. Hits<br>
in the F125 must therefore span two 32-bit words.<br>
<br>
2.) The FADC250 has a specification where the pulse time and pulse<br>
integrals appear as separate data types (i.e. they appear in
separate<br>
32-bit words). This allows the option of having a module output one<br>
of these but not the other. In practice, we will probably never want
to<br>
do this, but thee spec. allows it. To see the spec, look here, but<br>
be aware a few things in the headers have changed:<br>
<br>
<a class="moz-txt-link-freetext" href="https://halldweb1.jlab.org/wiki/images/d/db/FADC_Data_Format_V2.pdf">https://halldweb1.jlab.org/wiki/images/d/db/FADC_Data_Format_V2.pdf</a><br>
<br>
<br>
3.) For the FADC125, we could decide to couple the two words and<br>
eliminate redundant information such as the channel number,<br>
pulse number, and slot. This frees up enough bits to record a 12bit<br>
pedestal with every hit. I've drawn this out in the diagram below<br>
labeled Option1: to show how we could pack the bits in a format<br>
consistent with the spirit of the current F250 spec.<br>
<br>
4.) We could also follow almost exactly the format of the F250 spec.<br>
with the difference being that we need 7bits instead of 5 for the<br>
channel number in the F125. I've drawn this up as Option 2:<br>
below.<br>
<br>
5.) We could also have something completely different from either<br>
of these. In any case, we'll want the block header/trailer and<br>
event header words to follow the standard format for JLab modules<br>
whose current specification is here:<br>
<br>
<a class="moz-txt-link-freetext" href="https://halldweb1.jlab.org/wiki/images/5/58/JlabModuleDataFormat.pdf">https://halldweb1.jlab.org/wiki/images/5/58/JlabModuleDataFormat.pdf</a><br>
<br>
<br>
<img src="cid:part1.04080903.06050500@jlab.org" alt=""><br>
<img src="cid:part2.07030700.00050805@jlab.org" alt=""><br>
Regards,<br>
-David<br>
<br>
<div class="moz-cite-prefix">On 7/8/13 9:17 AM, Beni Zihlmann wrote:<br>
</div>
<blockquote cite="mid:51DABBF6.7070404@jlab.org" type="cite">
<pre wrap="">Hi All,
we have to come up with a list of specifications of the data we
want to have from the ADC. I would like to use this email to
initiate a discussion and put this topic on the agenda of the
next tracking meeting. By that time we should have a clear
understanding of what is needed so that the experts Cody
and Gerard can tell us what is feasible and what not.
cheers,
Beni
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