very cheap micro with CAN controller

then something like

-Lasse

I have no experience on automotive CAN systems, but I did work on a couple projects where CAN was used as an inter-board control bus.

For a project using the basic packets as defined by the CAN protocol and already implemented in hardware, (as opposed to, lets say, implementing IPv6 over CAN) the SW needed beyond the initialization of the controller is almost nill: Get an interrupt, read packet, mask off some of it, is it mine? yes, no, continue. No much more than that on the transmit side either.

-- Roberto Waltman

reminds me on the Philips SLIO years ago. Looks indeed interesting. I don't need much intelligence in the device as I wrote already. I can not figure out how to set up the CAN frame Ids used by the MCP25020. The device itself has not to talk the CANopen protocol but it has to fit in the communication of a CANopen network. I need in this case the Id to be configured in a way that it does allow standard CANopen devices to use there predefined connection set.

Regards Heinz

And you're sure you haven't contradicted yourself there?

I suspect CANopen pretty much owns the entire parameter space of a CAN bus it runs on. In that case the only way for a device _not_ to disturb the CANopen system is for it to speak CANopen itself.

I have seen simple CAN devices marketed as CanOpen devices, that happened to use the same CAN IDs as the PDOs for a specific CanOpen slave number. No SDOs and no NMT support.

Some CanOpen masters communicated with such devices, others refused to communicate due to missing NMT responses or the master could not read parameters (no SDO support).

wrong, CANopen can co-exist with other CAN-Traffic. You even can exchange data between "CANopen" nodes and "foreign" nodes.

Oliver

Let it say this way. CANopen as a system can interprete messages of simple sensors as CANopen PDOs (and visa versa). A single CANopen node can arrange a receive PDO for such messages and put the content according to its own mapping rules in its own object dictionary. Of course, such a node will not react on NMT messages or accept configuration via SDO transfers.

Regards Heinz

If cost is really an issue, you might find that a PIC18F25K80 micro coupled with an MCP2551 transceiver will be cheaper than the LPC11C22 with its built-in transceiver. The only thing to watch for is if you're planning on having a large number of unpowered nodes on the bus and/or long cable runs, the MCP2551 gives a maximum leakage current of

Thanks. I'll ask the local Distri for prices.

Heinz