Experimental Physics and
Industrial Control System

[email protected] · Thu, 16 Aug 2001 13:59:16 +0200

  > We need to monitor about 700 thermocouples for the SPEAR3 upgrade.
  > There will be about 40 TCs on 18 girders distributed around the 230m
  > ring circumference.  The present plan is to monitor the temperatures
  > at a few second intervals.  We have a couple of quotes from PLC
  > vendors, but they are fairly expensive.

  > Does anyone have a suggestion for hardware and software to
  > accomplish our task?  Of course the aim is to get the temperatures
  > into an IOC.

As our ring is about the same size and BESSY heavily uses CANbus the
suggestion is quite obvious:

There's a number of commercial multiple thermocouple controllers with
CAN field bus interface. A (number of) slow CAN line(s) around the ring
would probably still provide enough bandwidth for your needs. Any (even
an existing) IOC equipped with a VME CAN card would collect the data.
Polled mode or event triggered data flow as the TC controllers allow.

Segmenting the ring and having an IOC per segment would allow higher CAN
speed thus more bandwidth.

The main problem might be that the TC controllers usually handle 4 or 8
TCs max, so you would have to have multiple controllers per girder.
Probably a bit on the expensive side.

*Shrug* ?!

Ralph

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System