# Modbus TCP **URL:** \ **Category:** Getting Started\ **Created:** [November 11, 2021, 10:43am UTC](https://forum.xojo.com/t/modbus-tcp/66610 "2021-11-11T10:43:55Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Noel\_Wetischek](https://forum.xojo.com/letter_avatar_proxy/v4/letter/n/90db22/32.png) [@Noel\_Wetischek](https://forum.xojo.com/u/Noel_Wetischek)\ **Post date:** [November 11, 2021, 10:43am UTC](https://forum.xojo.com/t/modbus-tcp/66610/1 "2021-11-11T10:43:55Z")
Hello, I 've readen some post but no response. I try to develop a soft to command an logic controler The communication protocol is modbus TCP Is somebody have class to communicate in modbus TCP or tips to make it thanks in advance Noel ---
**Author:** ![Dennis\_Hoskins](https://forum.xojo.com/letter_avatar_proxy/v4/letter/d/bb73d2/32.png) [@Dennis\_Hoskins](https://forum.xojo.com/u/Dennis_Hoskins)\ **Post date:** [November 11, 2021, 2:13pm UTC](https://forum.xojo.com/t/modbus-tcp/66610/2 "2021-11-11T14:13:30Z")
Noel, I have used a C library on Github that provides support for Modbus TCP and EtherNet/IP. I have not used the Modbus TCP portion but the EtherNet/IP works very well with Rockwell ControlLogix PLCs. The Github URL is: [https://github.com/libplctag/libplctag](https://github.com/libplctag/libplctag) I’ve written a Xojo wrapper module for the library. You can get it at: [libplctag](https://drive.google.com/file/d/1Y6rr__AWo-14YXHDPWGDefx71pcUGsVK/view?usp=sharing) The wrapper is written for version 2.3 but it should work for the current 2.4 version. I usually put the dll file in the same folder as the executable. Dennis ---
**Author:** ![William\_Reynolds](https://forum.xojo.com/user_avatar/forum.xojo.com/william_reynolds/32/565_2.png) [@William\_Reynolds](https://forum.xojo.com/u/William_Reynolds)\ **Post date:** [November 17, 2021, 3:02pm UTC](https://forum.xojo.com/t/modbus-tcp/66610/3 "2021-11-17T15:02:42Z")
Hello @Noel_Wetischek ! You’ll notice that whenever someone posts about Industrial Automation there are only a small handful of us that work in this industry, so the replies aren’t as rapid as on other topics. I’ve done a great amount of programming for Modbus RTU, and it’s my understanding that Modbus TCP/IP is basically “Modbus RTU over IP”… or so I hear. I’m overdue to look into this topic so I’ll start digging now and see if there isn’t some help I can offer. Welcome to the Forum by the way! ---
**Author:** ![William\_Reynolds](https://forum.xojo.com/user_avatar/forum.xojo.com/william_reynolds/32/565_2.png) [@William\_Reynolds](https://forum.xojo.com/u/William_Reynolds)\ **Post date:** [November 18, 2021, 5:51pm UTC](https://forum.xojo.com/t/modbus-tcp/66610/4 "2021-11-18T17:51:20Z")
Hi Noel, I’m taking a look at the official spec on this (Modbus\_Messaging\_Implementation\_Guide\_V1\_0b.pdf) and it’ll take me several reads to absorb and not fall asleep. I’ll also likely find some software that emulates a Modbus TCP/IP “Client” (formerly referred to as “Master”) that’s intended for use debugging “Server” nodes. And I’m headed out for a week holiday with family, so it’s unlikely I’ll have more to contribute to this thread till after the 29th of the month. However, I really do hope I can be of help. My company has a need to fully understand and work with this protocol - so it’s something I plan on sticking to. Best of luck for now! ---
**Author:** ![Dennis\_Hoskins](https://forum.xojo.com/letter_avatar_proxy/v4/letter/d/bb73d2/32.png) [@Dennis\_Hoskins](https://forum.xojo.com/u/Dennis_Hoskins)\ **Post date:** [November 18, 2021, 7:17pm UTC](https://forum.xojo.com/t/modbus-tcp/66610/5 "2021-11-18T19:17:54Z")
William, This page, [http://www.dalescott.net/modbus-development/](http://www.dalescott.net/modbus-development/) has a good listing of Modbus simulators. Worth checking out. By the way, I confirmed my Xojo wrapper for the libplctag library (see my earlier post) does work with version 2.4 of the library. If you are on Windows, the 2.4 version is worthwhile since Windows performance has been improved. Dennis ---
**Author:** ![Noel\_Wetischek](https://forum.xojo.com/letter_avatar_proxy/v4/letter/n/90db22/32.png) [@Noel\_Wetischek](https://forum.xojo.com/u/Noel_Wetischek)\ **Post date:** [November 19, 2021, 8:48am UTC](https://forum.xojo.com/t/modbus-tcp/66610/6 "2021-11-19T08:48:08Z")
Thanks a lot Dennis and William I’ll try your wrapper soon. I have first to understand how to call/load the external library Noel ---
**Author:** ![Philip\_Stenson](https://forum.xojo.com/user_avatar/forum.xojo.com/philip_stenson/32/5995_2.png) [@Philip\_Stenson](https://forum.xojo.com/u/Philip_Stenson)\ **Post date:** [October 23, 2026, 5:43am UTC](https://forum.xojo.com/t/modbus-tcp/66610/7 "2026-10-23T05:43:19Z")
Hi @Dennis_Hoskins Is the wrapper still around ? The Google link seems to be not working 🙏 Many Thanks 😀 ---
**Author:** ![Jean-Yves\_Pochez](https://forum.xojo.com/user_avatar/forum.xojo.com/jean-yves_pochez/32/21769_2.png) [@Jean-Yves\_Pochez](https://forum.xojo.com/u/Jean-Yves_Pochez)\ **Post date:** [October 23, 2026, 10:03am UTC](https://forum.xojo.com/t/modbus-tcp/66610/8 "2026-10-23T10:03:16Z")
Hi there, I made this small library / app to connect to my hitachi heat pump using modbus it is a reusable library all written in xojo. hope this helps. _ **tested on macos only but should work on other platforms** _ > **[GitHub - JYPochez/VNS-Xojo-Modbus: a small library and example Xojo app to connect to...](https://github.com/JYPochez/VNS-Xojo-Modbus)** > > a small library and example Xojo app to connect to a device using Modbus