MB RTU slave, Timeout error with baud rate > 19200 #203
Description
Hi.
Thanks for so powerful library
Spec: ESP32 WROOM, ST3485EB (3.3V), Switchable termination resistor 120R, Arduino IDE, Scan rate time = 1S.
Library 4.0.0:
I use Mb RTU with around 100 write/read registers and I don't have any issue with baud rate <= 19200.
Higher baud rate cause the timeout error.
To eliminate the bug from my project, I created simple Arduino code with single Modbus register based on your example, and problem is exactly the same.
Can you suggest something please?
Increase the scan rate time to 2s didn't help.
After when I updated the Library to 4.1.0 I have:
- Timeout error
- Read error: framing error
- Write error
My simply code:
/*
ModbusRTU ESP8266/ESP32
Simple slave example
(c)2019 Alexander Emelianov (a.m.emelianov@gmail.com)
https://github.com/emelianov/modbus-esp8266
modified 13 May 2020
by brainelectronics
This code is licensed under the BSD New License. See LICENSE.txt for more info.
*/
#include <ModbusRTU.h>
#include <SoftwareSerial.h>
#define REGN 0
#define SLAVE_ID 1
#define MB_Enabled_pin 5
#define MB_RX 16 // D7
#define MB_TX 17 // D6
SoftwareSerial RS485Serial_S(MB_RX, MB_TX);
ModbusRTU mb;
//#define SSerialTxControl 5
void setup() {
// <= 19200 ALL WORKS FINE // > 19200 Timeout error
RS485Serial_S.begin(38400, SWSERIAL_8N2);
mb.begin(&RS485Serial_S, MB_Enabled_pin); //or use RX/TX direction control pin (if required)
mb.setBaudrate(38400);
mb.slave(SLAVE_ID);
mb.addHreg(REGN);
mb.Hreg(REGN, 100);
}
void loop() {
mb.task();
yield();
}