Experimental Physics and
Industrial Control System

[email protected] · Mon, 11 Apr 94 09:52:49 -0500

This is to add an extra requirement to Chips list. This is NOT for June 1 but
for the future.

I believe that at APS we will have a real need for a CA Concentrator. Let me
explain.

APS will ultimately have ~36 beam line sectors. Each sector will have an
arbitrary number of workstations that can potentially want info from the APS
accelerator control system. If we merely use gateways and access security then
each beam line CA client will use resources in one or more of the controls
IOCs. Since this is an unknown and potentially very large usage of ioc
resources, especially memory, this could be a major problem.

I can think of an easy out. For each sector there is an IOC for control of the beam
line insertion device. This beam line IOC is managed by accelerator controls
not by the beam line users. It seems natural to use this IOC as a concentrator.
We (accelerator controls) could define records to link to all accelerator PVs
needed by the users. A user connects to one of these records rather than to
the actual IOC containing the PV to be monitored/controlled. No matter how
many users connect to the beam line ioc, the number of channel access
clients connected to the rest of the control network will not change. The
worst thing the users could do is cause problems with their beam line ioc.
With proper design this should only affect them and not the users of other
beam lines.

I know that concentrators were discussed in the past especially with SSC. Bob
Dalesio, Jeff Hill, and others who were involved in the SSC discussions
probably have a lot to add to this discussion. We still need this capability.
At APS we are already seeing memory problems on iocs with insufficiant memory.
Although more memory will buy us time it is not the proper solution to a
problem that will only get worse.

Marty Kraimer

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System