Hi Surendra, Could you provide more information about your implementation? Do you have other tasks whose priority higher than FMB_SERIAL_TASK_PRIO option and how high if it is? Are these task(s) doing flash access (nvs) or disable CPU cache? Is the FMB_TIMER_ISR_IN_IRAM option set in your kconfig? C...

Hi @waterfox, - How do I set the stop bit to 2? I didn't find any option for this like in uart. The modbus master supports UART_STOP_BITS_1 option set in the serial port components\freemodbus\port\portserial_m.c:xMBMasterPortSerialInit(). However it should not cause any communication issues. Here I ...

The master device must knows register map of your slave (parameter structure) then it can set parameter of any type correctly and stack will transfer it to the slave device parameter structure. Good luck!

I agree that it is little bit unclear but this is how standard printf shows the float value made from incorrect bytes. How would you expect to print the float in this case (NAN)? The Modbus stack in this example just transfers the value of registers into its place of concrete parameter but how to pr...

Hi Chriserke, The approach you showed in your code must work. I guess the reason for the float value = 0.0000 is that you are writing the incorrect value of registers from mb_addr=1 and they are not correspond to correct float value. The printf("Holding reg value, %f", holding_reg_params.data_chan2)...

Hi @waterfox,

Let me place the link to github discussion about this issue here:
https://github.com/espressif/esp-idf/issues/5031

Let me know if you have progress in investigation of this issue.

EDIT: I tried the master version (4.1) and the same issue pops up. So i guess ill get back to debugging the data lines for now I just checked the v4.1 branch, for sure it is free of these issues and modbus_slave can communicate just fine. Probably you have some other (may be hw connection) issues. ...

Hello, What I can suggest you is to download the latest release of ESP-IDF and try to make a few changes manually in the components/freemodbus/port/portserial.c, components/freemodbus/modbus/mbascii.c of Visual GDB IDF folder. Unfortunately I don't know the actual commit ID and can't provide a patch...

I still do not know the correct commit ID (it is old preliminary version) but goal of change I provided just to check issue. Could you please rebase your ESP-IDF on master? The latest master has all required fixes and ASCII mode shall work just fine. Please let me know the result.

Thanks.

Hi @jaspernorth,

The protocol you provided is not the Modbus protocol but some custom protocol. ESP-IDF does not support this protocol.

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Alex