Dealing with serial ports (Rs485)

Sonderval

Alright, I know this is a long shot...

Bit of an engineering problem. I have a 15 pin RS485 controlled stepper motor and am looking for a way to connect it up to my pc. So far, I have been unable to find a serial card with the required d-sub 15 pin connection - they just dont seem to exist.

Can anyone shed some light on this?

DublinDilbert

You'll need to find the pin out for the RS485 connector on the stepper motor.... with RS485 there is no standard pin out, that I'm aware of.

RS485 should just require you to connect to the GND and the High and Low signal lines....

On the PC side you'll need an RS485 level shifter connected to a serial port.

What software are you going to use to communicate with the motor driver? are you going to write this yourself?

Sonderval

Hey DD, thanks for getting back with that.

I have the pinout diagram for the DB 15 connection to the stepper motor alright. I have a PCI card that has RS485 port, but they are 9 pin, not 15. Kinda throws a spanner in the works.

I have some software for the motor that should run it via RS485 - again though, I suspect they designed it to run via a 15 pin RS485 serial port, rather then through the 9 pin port I have. I am tempted to try a DB 9 to DB 15 converter (those old vga adaptors), though I know in my head this won't do it.

I am not against programming for this thing, though I have no serial port programming experience (though I am a decent programmer). I presume its not hugely difficult to write code to output pin signals?

So as I understand it, RS485 only requires GND, and those 2 other pins? Everything else can be custom coded, so to speak?

DublinDilbert

I wouldn't use a 15 pin to 9 pin converter, you could quite possibly damage something... These type of situations are usually one for the soldering iron and make one up...

If you don't have a soldering iron you could always cut a cable with a 9 pin end on it, and a cable with a 15 pin end on it, and splice the 3 wires together. If you do this approach always check it with a multi meter that the correct pins at one end are connected to the correct pins at the other end...

If you want you can post here the pin-outs of the 15 pin connector and the 9 pin connector and we'll see what needs to be connected to what.

Before trying to get the software running, i would make sure i have the right lines connected at the physical layer... it might also be useful to have an oscilloscope handy for debugging the software & connection...