How to use Modbus TCP in C++ with libmodbus in Visual Studio 2017

Putting this video out there in the rare chance this helps someone else.
This is a brute force, caveman-like method of including the library.
If anyone has a better method of using libmodbus in Windows Visual Studio, please comment below to commend below. Will be pleased to learn.
Note: I am aware that the library comes with a example on how to compile libmodbus on VS2008, but unfortunately it does not work for me.

[@Ackerman-iq3fl]

Thanx man !!
This video helped a lot, now I am able to perform read/write operations..

[@nemanja8676]

You saved me, tnx bro !

[@yutso3177]

Thanks for your clear and detailed tutorial. It really helps!!

[@AbhishekBade1310]

weach functions displays an errno when a specific libmodbus functions fails to do its task so i waned to ask whether the string attached to that error is also shown in the output which describes what that errno means? if so how can i add that to the throw in exception handling? thank you.

[@BillBartol]

Very helpful! Thank you!

[@mb_3000]

Hi, I used your video to write code for connecting modbus mb3000 and I've managed to connect but I get error saying gateway is unavaliable. Do you have an idea on how to fix this problem?
I am using vpn connection and only this code to configure the data.

[@joshuacvzn]

I did as shown in the video, but when I compile (minute 15:36) the error appears "undefined reference to `modbus_read_registers', undefined reference to `modbus_strerror', undefined reference to `modbus_new_tcp'...", how can I solve this problem ?
I'm using Dev C++ because my pc version doesn't work this visual studio

[@chlow1627]

I would guess your code cannot find the modbus library you included. You may an issue with linking the library to your IDE. Unfortunately, I am not familiar with Dev C++ interface, so you have to look for other tutorials on the linking files within the same folder

[@anshuman2952]

Thanks a lot for the read function. I would like to ask if there is a function to write to registers through MODBUS as well. If so, how to do that? Thank you.
Also, is this code only viable for modbus-tcp or can we use it for communication done in modbus rtu as well?

[@chlow1627]

Yes, i believe there are functions to read and write modbus registers. And to use for modbus rtu, use modbus_new_rtu() instead of modbus_new_tcp()
You may find documentation of the library's available functions at the main website. libmodbus.org/
This build is done using v3.1.7, so documentation is here libmodbus.org/olddocs/v3.1.7/libmodbus
Do consider supporting the project. :)

[@anshuman2952]

@@chlow1627 Thank you very much for the timely response. It was very helpful.

[@anshuman2952]

Will modbus_connect(mb) return -1 if there is a usb-rs-485 converter connected to a COM port but the converter itself is not connected with any device?

[@chlow1627]

@@anshuman2952 Hi, sorry for late reply, on my code, it exits with an exception error. Haven't had time to really figured out how to resolve this

[@anshuman2952]

I understand. Thank you very much for trying for my sake.​@@chlow1627

[@AbhishekBade1310]

I want to execute a DLL made in cpp using libmodbus inbuilt api's and run that DLL in csharp so is that achievable? If so, then any tips on how I can make that work?

[@chlow1627]

Unfortunately, I am not too familiar with DLL implementation.
I believe the repo owner already compiled some sample DLL. Prehaps you could look into repo for that.

[@stubborn176]

It is definitely achievable. You just need to make a project in C/C++ that exposes some API, the project will be build as dll project and a C# wrapper over it.

[@pere8641]

Thanks !!! Quite useful ! !!!!

[@Anas0473]

I know this is an old video, but i hope you can help.
I can't get it to run at 10:34 in the video. It gives me 8 errors of unresolved external symbols. I am running the latest version of Visual Studio Community 2022, that being version 17.5.1 and version 3.1.10 of the libmodbus. I would greatly appreciate it if you have any solution to this and are willing to help.

[@chlow1627]

You are in luck. Maybe more details about the error message?
I happen to see this. If I recall correctly, I saw unresolved errors when I missed out certain linkages, so maybe step through the video again ?
Also, Did you include extern "c"?

[@Anas0473]

@@chlow1627 I saw it again and figured it out :D
I got a problem that said something about the preprocessor definitions being undefined. On Google someone said that I could go to C/C++ settings -> Advanced and type disable the specific warning 4996 and it worked.

[@joydeeppaul2602]

requesting you to share the code

[@chlow1627]

It will not work. You really have to set these configurations on your computer

[@techwishsolutions]

thank you!