Modbus RTU over TCP (Simex Transmitter and Advantech Server)

[Christo89]

Hey Guys,

somehow i am not able to get a connection over TCP IP using RTU Mode (reading values) from a  transmitter which is hooked up to an advantech EKI 1542 Server. The Port is configured as an RS 485.

i am using the modbus library and i tried to adjust the MB serial read holding registers vi to accept a TCP IP Socket input instead of an INSTR. Do you have any suggestions?

Thanks a lot for the forum support!

[Christo89]

i also tried the TCP connection vi and the MB ethernet but this gives me an error 56

[ValkoA]

Hi Christo and welcome to NI Forums!

Is this the ModBus library you are using? If so, I'd recomend to check out the newer, object based library available here. It has a more straightforward setup, especially for using TCP connections. You'll find an example VI for using a master, as well as a slave device, and these you'll be able to use right away without much modification. The code'll look like:

Please test your device communication using this library.

Kind regards:

Andrew Valko

NI Hungary

[Christo89]

hey thanks for your help. i finally got it to work modifying the old modbus library so that the serial vis take in a tcp/ip socket 🙂

cheers

[ni_serg]

Hello! can you shared your result vis.

[cba.at]

Hi Christo89

i have at the moment the same problem as you. Before starting to modify the old lib I have found your solution. It would be very nice from you to share your lib!

christoph

[Christo89]

hey guys

sorry for the delayed answer.

sorry i dont have the vis at hand right now. but i can try to explain the fix

it was a pretty easy fix afterall. i opened a connection to the server with the visa open vi putting in a tcp/ip socket.

then i fixed the the MB Serial Master Query Read Holding Registers and its sub vis to take the tcp/ip socket as an input.

in the MB serial receive vi you have to delete the bytes at port property node and replace it with read visa with a byte count of 1024.

delete the upper error wiring due to errors related to the socket thing and thats it. works like a charm 🙂

[Luong.Tran]

Hi Christo89

Would you mind please share your modifieded for Modbus RTU over TCP !

 

Thanks and Regards

 

Luong.Tran

[natasftw]

Date Last Visited

‎11-28-2013 10:20 AM

What do you think the odds are that he'll reply?  You'll have more luck trying to implement the code he suggested