MAX13487e - Error 227

[markvdberg0]

ModbusMaster version

4-20ma/ModbusMaster@^2.0.1

Arduino IDE version

Visual Studio Code - PlatformIO

Arduino Hardware

ESP32 on Arduino codebase via PlatformIO. With a MAX13487e.

Scenario:

Reading a three phase network analyzer, slave device 1, baud 9600.

Steps to Reproduce:

A raw serial message read/wrtie does produce the right message and response from the device. Somehow when using the ModbusMaster library I keep getting an Error 227.

Response with code below: 01 03 01 66 00 02 25 E8 01 03 04 3C A6 43 6A A7 5F;

        void sendModbusRequest() {
          uint8_t request[] = {0x01, 0x03, 0x01, 0x66, 0x00, 0x02}; // Device 1, Function 3
          uint16_t crc = calculateCRC(request, sizeof(request));
          // Append CRC to request
          uint8_t crcLow = crc & 0xFF;
          uint8_t crcHigh = (crc >> 8) & 0xFF;
          Serial2.write(request, sizeof(request));
          Serial2.write(crcLow);
          Serial2.write(crcHigh);
        }
        //Serial2.begin(9600, SERIAL_8N1, BOARD_485_RX, BOARD_485_TX);
        void readModbusResponse() {
          int availableBytes = Serial2.available();
          if (availableBytes > 0) {
            Serial.print("Response: ");
            while (availableBytes--) {
              int byteReceived = Serial2.read();
              if (byteReceived == -1) break; // Just in case
          
              // Print each byte in HEX format
              if (byteReceived < 16) {
                
                Serial.print("0"); // Print leading zero for single digit hex values
              }
              Serial.print(byteReceived, HEX);
              Serial.print(" "); // Add space between bytes for readability
            }
            Serial.println(); // Newline after the complete message
          } else {
            Serial.println("No response");
          }
        }

Current not-working code for ModbusMaster:

        void connectmodbus(){
        
          Serial2.begin(9600, SERIAL_8N1, BOARD_485_RX, BOARD_485_TX);
        
          node.begin(1, Serial2);
        
          pinMode(GPIO_PUSE, OUTPUT);
        
          tick.attach_ms(1000, []() {
            digitalWrite(GPIO_PUSE, 1 - digitalRead(GPIO_PUSE));
          });
        
          pinMode(BOARD_POWER_ON, OUTPUT);
          digitalWrite(BOARD_POWER_ON, HIGH);
        
          pinMode(BOARD_485_EN, OUTPUT);
          digitalWrite(BOARD_485_EN, LOW);
          
        }
        void loop(){
         static uint32_t i;
          uint8_t j, result;
          i++;
        
          // set word 0 of TX buffer to least-significant word of counter (bits 15..0)
          //node.setTransmitBuffer(0, lowWord(i));
        
          // set word 1 of TX buffer to most-significant word of counter (bits 31..16)
          //node.setTransmitBuffer(1, highWord(i));
          
          node.clearResponseBuffer();
        
          result = node.readHoldingRegisters(0x0166,2);
        
          //readModbusResponse();
          
           if (result == node.ku8MBSuccess) {
            Serial.println("Request successful");
            // If successful, read the data
            for (uint8_t i = 0; i < 2; i++) { // Assuming 2 registers were requested
              uint16_t data = node.getResponseBuffer(i);
              Serial.print("Register ");
              Serial.print(i);
              Serial.print(": ");
              Serial.println(data, HEX);
            }
          } else {
            Serial.print("Request failed with error code: ");
            Serial.println(result);
          }
          //sendModbusRequest();
          delay(1000); // Wait a bit for the response
        }

Expected Result:

Response value from device >> 3C A6 43 6A

Actual Result:

Error 227.