Can't receive serial data in .net 2.0, using rs232 to rs485 converter

Question

I've done a good deal of RS232 work using the .Net 2.0 serialport class. I've never had trouble with it, until today.

I'm communicating with a piece of company hardware that uses the RS485 protocol. I'm using an RS232 to RS485 converter device from B & B electronics.

I can send data just fine, and see it received on the other side. However, my data_received event NEVER fires, and even using BytesToRead I never see anything coming back.

ReadExisting comes up empty as well.

We fired up 232Analyzer, and I can send AND receive packets with that application. I'm assuming this has something to do with the .Net 2.0 serial class.

Any thoughts at all?

Answer 1

The serial port code in 2.0 and 3.5 is known to be pretty flakey.

Cast around and you'll find a few known issues - perhaps this one matches your symptoms?

Answer 2

It turns out (after hours of researching and trying) that setting this:

.DtrEnable = True

did the trick. I've never had to use the DTR properties before, but whether it's an issue with this one device I'm working with, or something else I'm missing - that did it.

I thought this might save someone else a headache down the road.