Subject: |
Allen-Bradley Vs. CAMAC |
From: |
Carl Dickey <[email protected]> |
Date: |
Mon, 28 Nov 1994 16:20:35 -0500 |
We have implemented both Allen-Bradley and CAMAC systems here at Duke.
I agree with everything that Bob, Steve and Chip have said about the systems.
However there are a few additional comments that I would like to make:
1. The AB system is capable of extremely high distance connectivity using
standard balanced transmission line. Fiber optic interfaces can be installed
for even greater distances. The Hytec VME based serial drivers connect using
low capacitance twisted pairs. I think that with U-Port adapters that we might
expect quality transmissions up to perhaps five hundred feet. (Our longest
connection is probably around three hundred feet. Perhaps Chip's group has
a more exact figure.) Also, Hytec makes an optical fiber adapter for this
serial CAMAC system. (Perhaps CEBAF is using this.) But I think that you
need to understand your distribution requirements in addition to your data
rate, or scan rate requirements.
2. We had a lot of standard CAMAC equipment on hand of SLAC origin. This
equipment was basically limited DAC, ADC and digital I/O functions. In order
to utilize the existing equipment, we implemented a number of conditioning
and fuctional I/O standards. For instance, when reading back the T-type
thermocouples on the Stanford accelerating sections, we utilized the
Analog Devices style I/O module system. This system also proved to be handy
for interfacing some RTD signals. In the case of the Analog Devices I/O rack,
we scanned the racks with CAMAC BIRA SAM modules. When controlling our
screen diagnostics and vacuum valves we interfaced standard BIRA digital
output modules (IDOMs) into solid state relays that energize solenoids.
(We specifically avoided stepper motors, but they can be handled in a
similar manner, I believe.) My point is that it is possible to limit the
number of CAMAC function modules and to utilize the old CAMAC equipment
by employing low cost, conditioning standards. Limiting the number
of CAMAC function modules that are required will potentially reduce your
software development overhead also.
3. Finally, I think that cost should be considered in the selection process.
While CAMAC is not the latest, and it is somewhat painful to work with
particularly in physical I/O layer, the medium is entirely functional and
sufficient for many if not most of the problems that we encounter in
acclerators, I believe. The question is, does CAMAC meet your requirements?
To recap, I would like to say that my experience with both the AB and CAMAC
extensions to EPICS is that they will both work and get the job done, in a
similar manner. There are positive and negative aspects to both systems, I
think. First, will both systems actually meet your requirements for data
rates, connection distance, and functionality? Second, if both system meet
the requirements, will existing equipment significantly reduce your costs.
Best wishes to all,
Carl Dickey, DFELL
- Navigate by Date:
- Prev:
re: digitizer boards Matthias Clausen DESY -MKV2/KRYK-
- Next:
Analog input record offsets Nick Rees
- Index:
<1994>
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
- Navigate by Thread:
- Prev:
Allen Bradley Configuration Marty Kraimer
- Next:
Analog input record offsets Nick Rees
- Index:
<1994>
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
|