Devicenet to RS485 Converters


Thread Starter


Looking for a Devicenet to RS485 Converter for 115Kbaud.

I've seen a lot of converters that do this, but I haven't found one that goes above 56Kbaud on the RS485 side.

I need to interface some RS-485 devices to a Devicenet network, and they can only do 115Kbaud. The device vender has a converter that will converts CANbus to RS-485 for their units, but I don't think that the CANBus will talk to the
Devicenet scanner that I'm using.

I've done some Devicenet in the past, but am relatively new to it. Typically work with Ethernet or ARCNET. I did look at the ODVA website, but unless you're a member you can't get to the technical stuff.


Robert Scott

I find it odd that you have a device that is not capable of running slower than 115Kbaud. Is it because the device really has that much to
send? If so, then you may have problems with overloading the DeviceNet side of things too. When RS-485 is converted to DeviceNet, the
actual number of bits sent is approximately doubled due to the protocol overhead. So you will be sending 230K bits per second on the CAN
bus. Unless this is the only device on the bus, you are allocating a large fraction of the bandwidth for this one device.

If the data needs are not that severe, perhaps you can get an intermediate 485-485 buffer device that drops the baud rate to 56K?

Matt Brugman

The vendor tells me that the device is only capable of 115K. The data protocol length is 5 bytes (1 byte of status bits, 3 bytes of data, and 1 byte for checksum).

I agree that it seems goofy that a device can only communicate at 115K, but I'm stuck with what the vendor can do.

Originally, the vendor told us that it would communicate RS-485; and that they would supply an converter to go "at the front of the line" for Profibus or Devicenet. Our application calls for low cost, so I wanted to avoid Profibus and go Devicenet (my processor can do either). When it came time to order, the vendor stated that it's either CANBus or Profibus.

I made some decisions based on the original Devicenet concept, so now I'm kinda stuck.