Experimental Physics and
Industrial Control System

[email protected] · Thu, 15 Apr 1999 09:39:18 +0200 (CEST)

>>>>> "B" == Bill Brown <[email protected]> writes:

 B> We have an upcomming project that requires a field bus.  We're
 B> seriously considering CAN bus, which looks like a good fit from a
 B> systems point of view.

 B> One of the requirements is that we generate a spec for the vendor in
 B> the very near future.  Are there COTS CAN Bus devices (a/d, d/a, binary
 B> i/o) that the vendor could integrate into his product which would make
 B> our specification a little more "bullet-proof?"

 B> We don't want to ask a vendor to invent his own CAN Bus device for this
 B> project; that seems like a sure way to cause a lot of grief.

 B> We would really like the interface to be at the digital rather than the
 B> analog level.

 B> Any pointers/suggestions would be greatly appreciated.

 B> --

 B> -bill

 B> p.s.  We've got the i/o going in our compactPCI chassis running EPICS
 B> R3.12.b12, using "out of the box" drvIpac stuff and a home- grown
 B> (groan?) driver layer for the cPCI-200 IP carrier.  We'll use the same
 B> approach for the mentioned project, hopefully with the existing CAN Bus
 B> controller support in EPICS.

 B> The only really ugly part of the whole thing is having to add some
 B> conditionally compiled lines to take care of the byte-swapping required
 B> to go from big-endian (PPC) to little-endian (cPCI).

 B> OTOH, the current project does not require the use of interrupts, so
 B> that feature remains to be implimented.

 B> These changes are confined to the IP pack driver and to drvIpac.c

Hi Bill,

AFAIK ther are three different CAN protocols heavily in use, the CANOpen
(European standard), OpenDeviceNet (introduced by Allen Breadley but now
supported by the Open Device Net Vendor Association, more common used in
USA) and the SDDS protocol from Honeywell.

We at BESSY have an I/O system installed that is compatible to CANOpen.
This I/O system runs very reliable and is a very flexible way to interface
hardware. We use the CANOpen standard because in Europe are several
vendors for CANOpen compatible I/O. In USA it may be more reasonable to use
the OpenDeviceNet standard. 

Anyway, you may try the following links:

BESSY approach: the CAN related papers available at
	http://www-csr.bessy.de/control/Hard/

several links to CAN related sites
	http://www-csr.bessy.de/control/Hard/fieldbus/

OpenDeviceNet Vendor Association
	http://www.odva.org/

Hope this helps......
--[[text/plain]]

Joachim

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System