How to command RS485 with LABVIEW?

[toby 744]

I'm relatively new to Labview and having trouble producing a program to communicate with a "Eurotherm 2704" module via an rs485 connection. All suggestions greatly appreciated.

[Chris_Rake]

RS-485 describes the physical communication layer. Typically a RS-485 interface uses a standard 16550 UART and is used just like an RS-232 COM port on your computer with a couple of differences. RS-485 interfaces often can be set to different transceiver modes (4-Wire, 2-Wire Auto, etc.) and the networks can be multi-drop.

In your application, it sounds like you're trying to communicate with a single instrument. In that case here is what you will need to do:

- Connect ground of the RS-485 interface to ground of your device.
- Connect TX+ and TX- of the RS-485 interface to RX+ and RX- of your device.
- Connect RX+ and RX- of the RS-485 interface to TX+ and TX- of your device.
- If RTS/CTS flow control is used, repeat the above steps for HSO and HSI
(handshake out/in).
- Open and configure the RS-485 interface in LabVIEW (using NI-VISA for example). Make sure the baudrate, data bits, parity, and handshaking are all set up correctly.
- Now you should be able to read/write data to/from your device.

If your application is more complex (using a 2-Wire configuration or multi-drop), let us know!

[gemstone]

Hi,
Rake!
I want to use RS485 2-wire mode to communicate with two device.one is a pc.the other is a rs device.But I do not know how to connect the two machines.Now I have a RS232/485 convertor.I connect them like that.
pc:device
1--1
4--5
5--4
is this right?if not,pls tell me.
besides this, when i use rs232 mode,i have checked all details but do not find error.I connect three pins
5-5,2-2,3-3(2-3,3-2 normally.but i find pin3 in device is in high voltage level when the power is on.so connect them like this).am i right,too?
Thanks a lot.
stone

[eronides]

Chris.

Good Afternoon. So, If I do what u saying I'm gonna be able to connect RS485  - 4 wires to my MyRio Device?

I only wanna communicate with a single instrument For now.

[RavensFan]

You are replying in a 15 year old thread to a person whose last message on the forum was 6 years ago.  I don't think you'll get much help.

If his message at face value isn't helping you, then I suggest you create a new message.  Thoroughly describe your problem and what equipment you are using.

[eronides]

Knight of NI. The thing is: I have some temperature controlers here. An Autonics TK4s to be more specific. It has RS485 communication, but the thing is: How could I make the RS485 communication through labview and take the temperature to my front panel?

Maybe u have an example to show me?

Thank You for your reply

[cstorey]

Use the NI Example Finder, search "RS-485" and there are several examples that will help.