Communication with modbus devices

[SFuller]

Hi Peter,

It looks like you've made a lot of progress since your first post on this thread. So that I can get up to speed with where you are, could you clarify what you're trying to achieve at this point in time? If you could outline your setup and what you're trying to read, that would be useful.

Thanks,

Sean

[Versatilesamudia]

Hello Sean,

Thanks very much for taking time to look at my post and for your feedback. I am glad to say that I have indeed made some good progress since my first post on this thread. Then, I knew nothing about Modbus and was just getting to learn about it. Thanks to everyone on this forum who contributed towards getting me started with Modbus.

Just to enumerate the progress so far

1.)   I have been able to use both the I/O server and Modbus library for Modbus communication

2.)  I have succeeded in doing this with both RTU and TCP Modes

3.)  At some point, I had a problem communicating on RTU mode but latter realised that the Modbus server must first have to be set to RTU mode before it can be accessible via RTU

4.)  I have used both the I/O server and Modbus library to read the holding registers of the device available in my Lab. and I have also been able to read coils and write coils.

I am eager to explore more things that can be done with Modbus now that I have access to a Modbus device to practice whatever I read from books.

Any recommendations/suggestions of relevant documents that can get me grounded in Modbus will be highly appreciated at this time. I am currently reading Modbus Application Protocol Specification. I want to know what more could be done with Modbus.

Thanks

PETER

[SFuller]

Hi Peter,

Glad to hear you're getting on so well. I would suggest looking at some of the white papers available on ni.com. I have attached a few below for you to look into:

Getting Started with Modbus Communication in Lookout

NI Connectivity to Industrial Communications

Industrial Networking Based on Ethernet

Best of luck,

Sean

[Versatilesamudia]

Thank you very much Sean. I am really glad to have these links sent to me.

God bless you!

Regards,

PETER.

[smithd]

Sorry I disappeared for a bit -- NI week was upon us. Those links above should help a little bit, but we recently posted this series of documents:

http://www.ni.com/white-paper/52204/en/

Unfortunately the second link is broken right now, it is supposed to go here:

http://www.ni.com/white-paper/52135/en/

Instead, the first two links point to the same place. Should be fixed soon.

[Versatilesamudia]

Thank you very much SmithD. I am happy to have these documents.

They certainly will take me some steps higher.

Thank you once again.

Regards,

PETER