On Fri, 27 Feb 2004, vitaliy ziskin wrote:
> I'm not sure if that is possible. Scalers get their TTL signal from
> this ribon cable which comes staright from the ABS rack 13 (lucky
> number). To do what you are sugesting we need to make another scaler
> channel (another epics channel is easy) , do we have an exra one.
That's exactly my point. Why do we use the epics for this
purpose? The hardware signal is out there already! Delivering a
signal through epics is equivalent of introducing more breakable
points along the way. The Flip-Odd signal we produce is already a
TTL signal.
As for the epics channel: Of course it doesn't hurt to have this
one as well. What I am suggesting is that we should use a
hardware signal read by a device and distributed by the epics,
instead of a software bit that we can set (means any other
software can change it - not error-prone).
And, that kind of channel is already in place; no software is
involved (other than epics server, off course), it is read
directly from the hardware signal. It is called
"sp2_6034e:flip_odd".
Thus, the conflict is not whether it is doable or not, but
finding the best approach. I vote for using directly the TTL
signal from the Compton electronics for scaler normalization.
Correct me if I'm wrong: The current setup is as follows:
1) Compton Controller flips the spin.
2) The flip-odd TTL signal is generated by the compton
electronics.
3) Compton controller sets the proper epics bit according to the
flip-odd state.
4) A digital I/O board (call it an out-register) produces a TTL
signal that supplies the scalers.
We can eliminate item 2&3 by using directly the TTL hardware
signal produced by the item-2. And, there is already an epics
channel that reads the same TTL signal produced by item-2.
(Finding a proper cable for the scaler channel is a small
detail.)
Maybe, I'm missing something, let's discuss this on
paper/electronics.
Cheers,
Taylan
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Taylan Akdogan Massachusetts Institute of Technology
akdogan@mit.edu Department of Physics
Phn:+1-617-258-0801 Laboratory for Nuclear Science
Fax:+1-617-258-5440 Room 26-402b
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