HTCC-AB02S RX2 issue

#1

Hi,
I’ve been struggling with a strange problem for several days now. I have a soil moisture sensor that sends data through a modbus (RS485 <> TTL) interface. I use a HTCC-AB02s because it has a second serial port. The process is simple, I send a request and get the data from some registers. But whatever I try I only get 7 bytes of data back while I see on my logic analyzer that 11 bytes are received. Does anyone have any suggestions?

    static void prepareTxFrame( uint8_t port )
    {
    	 digitalWrite(GPIO7 , HIGH); // Power up the modbus interface and sensor
       delay(500);

       
       //Send request to modbus sensor
      uint8_t request[] ={0x01,0x03,0x00,0x00,0x00,0x03,0x05,0xCB} ; // Sensor request (first 3 registers)

      for (int n=0; n<8 ; n++)
      {
        Serial1.print(char(request[n]));
      }

      delay(300);

       //recieve data from modbus sensor
      uint8_t serialBuffer[11] = {0} ;
      int i=0;
      
     while (Serial1.available()) 
     {
         serialBuffer[i] =  (char) Serial1.read();
         i++;   
     }
      Serial.println(i-1);
      
        appDataSize = 6;
        appData[0] = serialBuffer[3]; //Temp msb
        appData[1] = serialBuffer[4]; //Temp lsb
        appData[2] = serialBuffer[5]; // moister msb
        appData[3] = serialBuffer[6]; // moister lsb
        appData[4] = serialBuffer[7]; // EC msb
        appData[5] = serialBuffer[8]; // EC lsb

    digitalWrite(GPIO7, LOW); // Power down the modbus interface and sensor
    }
#2

hi,

we can’t find any problem from your code and your describe。

could you show more details（Connection of pins…ect.）?

#3

Hi jasonXu,

The RS485 interface is connected to pin 29 (RX2) and pin 30 (TX2). Baudrate is set to 9600-8-1-N.

#4

hi,

this buffer length is 8.

we have updated the code:


%E5%9B%BE%E7%89%87

#5

Super, thanks…problem solved.

#6

Do you think it would be possible to make this on HTCC-AB01, using the serial connected to USB chip?
Thanks!

#7

sorry, i can’t understand your mean well. can you explain more?

#8

The Rx and Tx pins aren’t connected to cp2102?
I meant if it’s possible to used even if the pins are connected to that chip.
Thanks

#9

Here the github link fails.

Can you please fix this link, or (re) provide your solution?

Thanks

#10

Here is a working solution,

#include <Arduino.h>
#include “Wire.h”
#define TIMEOUT 10 //time in ms for rs485 timeout

// To write and read from a soil moisture sensor RS485 using a RS485TTL module ‘k485’

byte buf[8]={0x01,0x03,0x00,0x01,0x00,0x04,0x15,0xC9};
uint8_t serialBuffer[12];
int size = 0;

void setup() {
Serial.begin(9600); // for debugging, do not use between writing to the device and listening for reply, or you will miss reply
Serial1.begin(9600); // pins rx2 - 36,tx2 - 37
pinMode(23,OUTPUT); // this controls the power to my peripherals using the df robot solar power mangement
}

void loop() {
digitalWrite(23, HIGH);
delay(500); // let the power arrive at the RS485 interface

Serial1.write(buf,8);
size = Serial1.read(serialBuffer,TIMEOUT);

//Serial.println("");  !!  This delayed the listening for the return from the sensor, causing failure

if(size)
{
for (int j; j<17;j++){Serial.printf(" gets %x ",serialBuffer[j]);}
Serial.printf(“size = %d “,size);
Serial.println(””);

int tempC = ((serialBuffer[3] << 8) | serialBuffer[4])/10;
int sMoist = ((serialBuffer[5] << 8) | serialBuffer[6])/10;
Serial.print("temp: ");
Serial.print(tempC);
Serial.print("  Soil_Moisture: ");
Serial.println(sMoist);
for (int n=0; n<9 ; n++)
  {
    Serial.printf("%x",char(serialBuffer[n]));
    Serial.print(", ");
    Serial.println();
  }
    appDataSize = 4;
    appData[0] = serialBuffer[3]; //Temp msb
    appData[1] = serialBuffer[4]; //Temp lsb
    appData[2] = serialBuffer[5]; // moister msb
    appData[3] = serialBuffer[6]; // moister lsb

}
Serial.println(“finishing loop”);
digitalWrite(23,LOW); // turn power off to periph
delay(2000);
}

Thanks, this site helped a lot.