FW: CANopen question

I don't know "the CANopen Way", but years ago I set up a command that told every node to reply once with its node ID, after waiting a time dependent on the ID plus a random extra delay.  I  "hoped" that any duplicate nodes would start transmitting more than a fraction of a bit-time apart.  It might have been smart to turn retries off for that transmission, but I did not bother with that.

It wasn't a robust method and took some seconds to run, but we used it during development to confirm that people had set all the ID switches correctly.

For the real machine, the "chorus reply" was not needed.  It was sufficient to detect the absence of any expected node.  If one node was missing, we only had to look at the physical location of the "missing" node to find the incorrect ID switch setting (or a dead node or bad connector).

The real machine had a fixed list of nodes that were expected and needed - we didn't have to support a variable number of "drop-in" nodes.

We also had an LED on each node, that toggled each time a message was received.  If some unexpected node answered and I wasn't sure what-all was SUPPOSED to be installed on that particular day during development, I would set up a repeating command to the unexpected node ID, so I could walk around and look for the toggling LED.

Primitive stuff.  The opposite of a standardized approach.


Rick Corey  | Software Engineer | Crane Aerospace & Electronics, Lynnwood WA 98046


From: [email protected] [mailto:[email protected]] On Behalf Of John Dammeyer
Sent: Friday, February 12, 2016 10:00 AM
To: [email protected]
Subject: [CANLIST] CANopen question

Suppose a technician accidentally installs two CANOpen motor drives with the same nodeID.  Or two pressure transducers or Inclinometers.  Anything that requires an external terminal and dongle to program the target ID.

Is there a standardized way to ask nodes to report their NodeID when there may be two on the bus with the same ID?

Thanks
John Dammeyer

"ELS! Nothing else works as well for your Lathe"
Automation Artisans Inc.
http://www.autoartisans.com/ELS/
Ph. 1 250 544 4950



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