From: Frank Geurts (geurts_at_rice.edu)
Date: Tue Mar 25 2003 - 17:33:17 EST
Zhangbu,
i haven't heard back from you ... what changes did you make?
-frank
John Mitchell wrote:
> Zhangbu,
> Indeed, what you want is the Local BUSY generated in Phillips 794 unit
> 2-6-4 (set as latch). Unfortunately, the Phillips 794 only has single
> GATE and GATEbar outputs. This is the reason that I used the GATEbar
> and a 2-fold coincidence to achieve a veto condition for the TOF logic
> PULSE unit (2-10-1).
>
> There are two options.
>
> 1) Use the TTL or ECL output of the 794 latch. Both are normally wired
> internally as GATE (although they can be changed to be DELAY, DELAYbar,
> or GATEbar). You will then have to convert to NIM (using for TTL-NIM,
> e.g. a LeCroy 688AL or Phillips 726) to provide the veto for your
> logic. This option has no effect on the TOFp logic and is preferable to
> the other option below. If you do this, you need to check to make sure
> that your final NIM signal actually has the same polarity as the 794
> GATE because there is some chance that the 794 is wired for a different
> function or that you will make an unintended polarity change in your
> logic level conversion. You can set/clear the 794 latch from the front
> panel.
>
> 2) Add a fan-out at the output of unit 2-6-4. If you choose this option
> then you must use a 100% duty cycle fan-out like a LeCroy 429A or
> Phillips 740. You cannot use a pulse generating unit like a
> discriminator or logic unit as a fan-out for this function. My
> preference would be to use a LeCroy 429A or Phillips 740 attached to the
> GATEbar output of 2-6-4. (I don't really want to put it on the GATE
> output and delay the start of the Local BUSY by an additional
> propagation delay.) The normal output of this unit would be connected
> to 2-10-1 to provide the input for the 2-fold coincidence (BUSYbar) just
> as the direct GATEbar output of 2-6-4 is now. You would use the OUTbar
> to give a BUSY signal to your logic. At present, I don't think there
> are any fan-out sections available in the TOFp logic in NIM bin 2, so a
> fan-out would have to be added in NIM bin 4.
>
> Let me know what you think.
>
> John
>
> At 1:27 PM -0500 3/24/03, Xu, Zhangbu wrote:
>
>>
>> Hi, Frank:
>> The BUSY sent to TCD will be taken care of by the TRIGGER.
>> What I need probably is the local BUSY from 2-6-4 to
>> 2-10-2 where the "pretrigger" is BUSY.
>> Thanks!
>> Zhangbu
>>
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