ImodbusRTUmaster()

ImodbusRTUmaster()

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)

Commands

Command	Arguments	Return Value	Operation
`ImodbusRTUmaster(serialPort, slaveId, functionCode, address, quantity, data, timeoutMs)`	`HardwareSerial& serialPort` — Serial port connected to RS-485 `uint8_t slaveId` — Slave address `uint8_t functionCode` `uint16_t address` `uint16_t quantity` `uint16_t* data` `uint16_t timeoutMs = 100`	`uint8_t`	Executes a single Master request immediately.

Example

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.
}

Precautions

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.

Built-in Commands in the Same Category

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Table of Contents

ImodbusRTUmaster()

Commands

Example

Precautions

Built-in Commands in the Same Category