Modbus TCPIP OPC Realtime

[dwhite_revoleng]

Can I run NI OPC Server on realtime systems? I am would like to run Modbus TCPIP on a realtime system without a remote windows PC.

What are my options???

[Rolf Kalbermatter]

Can I run NI OPC Server on realtime systems? I am would like to run Modbus TCPIP on a realtime system without a remote windows PC.

What are my options??

OPC probably never will run on real time. OPC is based on OLE and that is a huge system to add to a real time environment. As such it is probably not possible to create an OLE system that would not throw off any real time determinsme from the system. Also OLE is a closely protected core technology of Windows and Microsoft won't give out the source code just to anyone to port it to a competitive real time environment, even if porting it to a real time environment would technically be possible, what I highly doubt.

So your options are actually to go with a completely VI based ModBus library. There are several Alliance Members that sell VI based ModBus libraries and NI recently developed one based on the ModVIEW library from CIT Engineering where I work. I'm not sure what NIs plans and conditions are for this library but you can also checkout http://www.citengineering.com/pagesEN/products/modbus.aspx.

Rolf Kalbermatter

[David Wisti]

Can I run NI OPC Server on realtime systems? I am would like to run Modbus TCPIP on a realtime system without a remote windows PC.

What are my options???

Modbus TCP is quite a simple and well documented protocol. I have developed a Modbus TCP server and client on the NI cRIO with great success. These vis are not really ready for public release because not all the Modbus functions are supported. I'm willing to send you some examples if your interested. These examples will require you to learn more about the Modbus protocol.

[dwhite_revoleng]

Modbus TCP is quite a simple and well documented protocol. I have developed a Modbus TCP server and client on the NI cRIO with great success. These vis are not really ready for public release because not all the Modbus functions are supported. I'm willing to send you some examples if your interested. These examples will require you to learn more about the Modbus protocol.

Yes please forward these exsamples. I will be very interested.

Thank you,

[malef]

NI provides a free, downloadable set of VIs for Modbus communication under

http://sine.ni.com/nips/cds/view/p/lang/de/nid/201711

I think it will be part of PDS and supports RT. Up to now there is little documentation available.

I've tested Modbus TCP/IP connection with WAGO-I/O-750 and it works.

For us it's a great progress compared to OPC talk.

Manfred