M-Bus protocol with cRIO

[Quintino]

Hello everyone.

I have a cRIO-9074 and two Brunata HGP with the M-Bus communication. The cRIO has one Serial Port RS-232, and I'm using a RS-232 to RS-485 converter to communicate with other devices.

Does anyone knows how should I use the same RS-485 network to communicate with this Brunata using M-Bus?

There are some RS-485 to M-Bus converter, although I believe those converters only convert the signals and not the protocol. With this, how can I communicate with this Brunata using this converter? Or is there any other solution?

Many thanks.

André Quintino

[Romain_P]

Hello André,

Thank you for posting on National Instruments' forum.

The RS232 embedded in cRIO is not intended to communicate with devices but only to programm cRIO.

You'll have to use an I/O NI module to communicate with Brunata HGP. Converters M-Bus to RS-485 will convert your signal using the RS-485 protocol.

Regards,

[Quintino]

Hello Romain, and thank you for the reply.

Can you please tell me what NI I/O module are you referring? Is there any NI software for this module, or I need to develop all the M-Bus protocol?

If I understood, the M-Bus to RS-485 converters not only convert the signal but also the protocols, right? So the converser will have a different communication protocol than the Brunata, and I just need to send the right request frame to the converter and them it will do all the protocol converter work?

Do you know and recommend any M-Bus to RS-485 converter?

Best regards,

André Quintino.

ISR

[Romain_P]

There are no software intended to M-Bus protocol. You have to use a M-Bus to RS-xxx converter, and use a 9871 (4x RS-485) module for example.

About the choice of the converter, I only advise you to be carefull if the converter use the RS-485 (what does it communicate? what protocol it use?), just compare converters products for your application in reading manuals.

Did you try to contact Brunata for more explanations?

Best regards,

[Wayne.C]

Quintino,

You can use the builtin RS-232 port to talk to external devices via the NI-Visa functions.  This port is NOT just for configuring the cRIO.  I suggest you start by reading/comparing the specs for RS-232, RS-485 and M-Bus.