Florian:
One reason, perhaps the major reason, why PLCs are chosen for safety
systems and also for equipment protection systems is that they are
high-availability systems. The PLC can be relied upon to do its simple
job a much greater fraction of time than many other types of controls.
Additionally, PLCs have simple operating systems and easy control of
individual bits, making it simple to interface switches and buttons.
These aspects and more are what keeps the amount of necessary routine
system maintenance is quite low and the availability high.
Also, it is common that some of the bit outputs of PLCs are chosen so
that they do not change state on system restart (but this is not unique
to PLCs).
For monitoring (or controlling) a vacuum system, a PLC is a great
choice. The logic is clear and, with clear design of the specific
system, there is no risk that some other task will interfere with the
designed control of the vacuum system. Except for hardware failure of
sensors, switches, buttons, PLC, power, ...
EPICS IOCs are not expected to have the same high-availability fraction
as PLCs.
Pete
On 2016-04-05 2:52 AM, Florian Feldbauer wrote:
Hey all,
I'm working with EPICS now for several years to develop parts of the
Detector Control System for
the PANDA experiment.
For our luminosity detector we need to control a small vacuum system.
I had a look at various talks from EPICS meetings to see, how others are
building their control systems
and I have a question concerning this:
All the systems I have seen are using PLCs to control the valves of the
system.
What is the advantage of a PLC for controlling the valves?
Why not using an EPICS IOC for direct control running on a realtime system?
I never worked on vacuum systems before, and our vacuum workshop here at
Mainz
could not help me with this question.
Many thanks in advance for the help!
Florian
--
----------------------------------------------------------
Pete R. Jemian, Ph.D. <[email protected]>
Beam line Controls and Data Acquisition, Group Leader
Advanced Photon Source, Argonne National Laboratory
Argonne, IL 60439 630 - 252 - 3189
-----------------------------------------------------------
Education is the one thing for which people
are willing to pay yet not receive.
-----------------------------------------------------------
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