Modbus Master Serial RTU without RS485

gfia2000
Posts: 10
Joined: Mon Jun 01, 2020 2:17 pm
Location: Argentina

Modbus Master Serial RTU without RS485

Postby gfia2000 » Thu Sep 24, 2020 5:24 pm

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.
Hi! I'm a PCB designer and a Uc programmer from Argentinia.

rodmcm
Posts: 47
Joined: Sat Sep 02, 2017 3:31 am

Re: Modbus Master Serial RTU without RS485

Postby rodmcm » Mon Sep 28, 2020 1:05 am

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
Posts: 10
Joined: Mon Jun 01, 2020 2:17 pm
Location: Argentina

Re: Modbus Master Serial RTU without RS485

Postby gfia2000 » Mon Sep 28, 2020 11:26 am

rodmcm wrote:
Mon Sep 28, 2020 1:05 am
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.
Hi! I'm a PCB designer and a Uc programmer from Argentinia.

gfia2000
Posts: 10
Joined: Mon Jun 01, 2020 2:17 pm
Location: Argentina

Re: Modbus Master Serial RTU without RS485

Postby gfia2000 » Mon Sep 28, 2020 2:53 pm

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!!
Hi! I'm a PCB designer and a Uc programmer from Argentinia.

rodmcm
Posts: 47
Joined: Sat Sep 02, 2017 3:31 am

Re: Modbus Master Serial RTU without RS485

Postby rodmcm » Tue Sep 29, 2020 2:03 am

send null characters

gfia2000
Posts: 10
Joined: Mon Jun 01, 2020 2:17 pm
Location: Argentina

Re: Modbus Master Serial RTU without RS485

Postby gfia2000 » Tue Sep 29, 2020 11:40 am

rodmcm wrote:
Tue Sep 29, 2020 2:03 am
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!
Hi! I'm a PCB designer and a Uc programmer from Argentinia.

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