ImodbusRTUmaster() executes a single Master request immediately.

uint8_t ImodbusRTUmaster(HardwareSerial& serialPort, uint8_t slaveId, uint8_t functionCode, uint16_t address, uint16_t quantity, uint16_t* data, uint16_t timeoutMs = 100)

uint16_t data[10];
uint16_t readValue0;
uint16_t readValue1;
 
void setup() {
  ImodbusRTUmasterInit(Serial2, 9600);  // Set the Master's communication port and baud rate.
}
 
void loop() {
  uint8_t result;
 
  result = ImodbusRTUmaster(Serial2, 1, 0x03, 0, 2, data);  // Execute a single Master request immediately.
  if (result == IMODBUS_RTU_SUCCESS) {
    readValue0 = data[0];
    readValue1 = data[1];
  }
 
  data[0] = 1234;
  ImodbusRTUmaster(Serial2, 1, 0x06, 10, 1, data);  // Execute a single Master request immediately.
}

• Keep calling the Slave or Master execution function in loop().
• The data array size must be at least the requested quantity.
• Do not treat return codes BUSY and IDLE as communication failures.
• When sharing M and D with Cnet/MC Protocol, define a single final size and initialization order. Do not call ImodbusRTUMem() or ICnetMem() again at runtime.
• Memory allocation functions do not return success status. For nonzero sizes, verify that M and D are not nullptr before accessing them in user code.

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