Modbus Master Serial RTU without RS485

[gfia2000]

Hello,

I'm using a esp32 connect directly to other Uc (TI) and the communication between both of them is by Modbus RTU (not using rs485, only serial ports).

I can't receive the response messeage from Function 04 or write a coil from Function 05.

If anything have an idea or an example it will be welcome.

Thanks a lot.

[rodmcm]

Use something like Baseblock ComTest Pro to sample the messages on a PC http://www.baseblock.com/
You will need to connect with FTD module od similar

[gfia2000]

Use something like Baseblock ComTest Pro to sample the messages on a PC http://www.baseblock.com/
You will need to connect with FTD module od similar

Thanks u so much! I ve tried a lot of thingg and I forgot watch the signal by osciloscope. When I tried that, I have no response from the TI microcontroller because my partner forgot enable Serial communication...

I will refresh this post when I have a good result. The modbus communication is very important and there is no much related information for this enviroment.

Anyone can ask me why I choise Arduino IDE enviroment for the professional job.. and the answer is... Because if You can program C or assembly, arduino has no more problems than other enviroment.

[gfia2000]

Hi again. The next (and I hope the last) problem is:

How can I generate a silent interval between two frames. More detailed, an interval equal to character *3,5 or more.

If anyone know the answer, please post here! Thanks!!

[rodmcm]

send null characters

[gfia2000]

send null characters

Thanks! I fixed it yesterday.

If the library is required I can made it else I can receive questions about the format.

Good bye!