Experimental Physics and
Industrial Control System

[email protected] · Fri, 16 Jul 2010 08:58:25 -0700

On 18:17 Thu 15 Jul     , Mark Rivers wrote:
> Shifu's device is a TCP/IP power supply, talking a simple ASCII
> protocol.  When talking to the device it usually responds quickly, but
> occasionally the responses are very delayed.  Whether this is due to the
> device or to the APS network is not clear, but in any event sometimes
> the response does not occur until after the 2 second timeout specified
> in the devGpib file.  However, the device does appear to always
> eventually reply.

I have similar problems with a few of my networked devices.
In my case, I believe this is due to broadcast packets.
A (logical or physical) point to point connection (device <-> IOC ) solve that problem.
I believe the broadcast packets are nothing less than the CA protocol itself ;-)
In a perfect world, one should have a network with OPIs and another network for controlled devices. 
The IOCs are the bridges between both networks.

At APS, are controlled devices and OPIs on the same net?

-- 
Emmanuel

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System