Read RS-422

[Erik Wessel-Berg]

Is it possible to read RS-422 signals using LabVIEW. If so, where do I
set the options?

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for reply: remove IKKESPAM from address

[Croll, Andrew [SKY:1V43:EXCH]]

I have been trying to figure out a similar problem only I am trying to
talk to a RS-485 device. I don't have a RS-485 card though. Hence
I must use the serial port to communicate and a RS-232 to RS-485
converter. This is a fairly easy way to do things, many companies make
232-485 converters for around $50 (USD).

To talk to the serial port you can use visa or the serial port commands,
both seem to function well. If you have an RS-422 card in your computer
then you need to ask the manufacturer if they have labview drivers for
thier product. If they don't you are probably out of luck.


Andrew B. Croll
Optical Verification
Nortel Networks
Ottawa, Canada

Erik Wessel-Berg wrote:

> Is it possible to read RS-422 signals using LabVIEW. If so, where
do I
> set the options?
>
> --
> for reply: remove IKKESPAM from address

[Brian_Powell]

It depends on what you're trying to do. What options do you want to set? Are you trying to make a multi-device bus out of RS-422?

One way to think of RS-422 is that it is just RS-232 with differential electrical signals instead of grounded. (And it's got tighter restrictions on voltage levels.) So if you have just a single device, you can usually just connect your RS-422 device to an RS-232 serial port and it will just work. The Tx- and Rx- end up getting grounded.

However, RS-422 also defines a way of having one talker and many listeners. It's multi-drop like RS-485, but not nearly as flexible in terms of how you can address individual devices. If you're talking about needing to do that, you'll probably need to find an RS-485 card (like NI's card) to
talk to your RS-422 device(s).

I hope this helps.

Brian