ตัวอย่างการใช้งาน IOXESP32 Modbus RTU shield ต่อกับบอร์ดรีเลย์ Modbus RTU
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/* Dev by IOXhop.com */
void setup() {
Serial.begin(115200);
Serial2.begin(9600, SERIAL_8N1, 27, 26); // Rx, Tx
Serial2.setTimeout(100);
}
uint16_t CRC16(uint8_t *buf, int len) {
uint16_t crc = 0xFFFF;
for (uint16_t pos = 0; pos < len; pos++) {
crc ^= (uint16_t)buf[pos]; // XOR byte into least sig. byte of crc
for (int i = 8; i != 0; i--) { // Loop over each bit
if ((crc & 0x0001) != 0) { // If the LSB is set
crc >>= 1; // Shift right and XOR 0xA001
crc ^= 0xA001;
} else { // Else LSB is not set
crc >>= 1; // Just shift right
}
}
}
return crc;
}
void relayWrite(uint8_t n, bool setToON) {
if (n < 1 || n > 4) {
return;
}
uint8_t buff[] = {
0x01, // Devices Address
0x05, // Function code
0x00, // Start Address HIGH
n - 1, // Start Address LOW
setToON ? 0xFF : 0x00, // Data 1 HIGH
0x00, // Data 1 LOW
0, // CRC LOW
0 // CRC HIGH
};
uint16_t crc = CRC16(&buff[0], 6);
buff[6] = crc & 0xFF;
buff[7] = (crc >> 8) & 0xFF;
Serial2.write(buff, sizeof(buff));
Serial2.flush(); // wait MODE_SEND completed
if (!Serial2.find("\x01\x05")) {
Serial.println("Write to Relay error !");
return;
}
}
void loop() {
relayWrite(1, HIGH); // Relay 1 -> ON
delay(1000);
relayWrite(1, LOW); // Relay 1 -> OFF
relayWrite(2, HIGH); // Relay 2 -> ON
delay(1000);
relayWrite(2, LOW); // Relay 2 -> OFF
relayWrite(3, HIGH); // Relay 3 -> ON
delay(1000);
relayWrite(3, LOW); // Relay 3 -> OFF
relayWrite(4, HIGH); // Relay 4 -> ON
delay(1000);
relayWrite(4, LOW); // Relay 4 -> OFF
}