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#include <modbus.h>
/* Baud rate for UART */
#define BAUD 9600
/* To match the parameters of HardwareSerial Rx/Tx functions with the Modbus functions, wrappers around the ::read() and ::write() functions are required */
MB_StatusTypeDef ArduinoSerial_Tx(void* serial, uint16_t* buf, uint8_t* len, uint8_t* timeout);
MB_StatusTypeDef ArduinoSerial_Rx(void* serial, uint16_t* buf, uint8_t* len, uint8_t* timeout);
MB_StatusTypeDef (*MB_UART_Tx)(void*, uint16_t*, uint8_t*, uint8_t*) = &ArduinoSerial_Tx;
MB_StatusTypeDef (*MB_UART_Rx)(void*, uint16_t*, uint8_t*, uint8_t*) = &ArduinoSerial_Rx;
/* Single modbus device node */
modbus_slave_device modbus_dev_single;
/* Multiple modbus device nodes.. after all, what is the point of using Modbus in a single point-to-point connection? */
/* Not illustrated beyond the definition, but should be clear enough */
modbus_slave_device modbus_dev_multiple[10];
uint16_t reg;
void setup()
{
Serial.begin(BAUD);
/* Set the slave ID to 1 */
modbus_dev_single.slave_id = 1;
/* Attach the default HardwareSerial class instance to this node */
modbus_dev_single.modbus_uart = &Serial;
/* Continuously read this input register in superloop */
reg = 30001;
}
void loop()
{
MB_StatusTypeDef status = ReadInputRegisters(&modbus_dev_single, reg, 1);
if (status == MB_OK) {
/* Do something with data in the response buffer */
/* ... */
ClearResponseBuffer(&modbus_dev_single);
}
}
MB_StatusTypeDef ArduinoSerial_Tx(void* serial, uint16_t* buf, uint8_t* len, uint8_t* timeout)
{
HardwareSerial* _serial = static_cast<HardwareSerial*>(serial);
if (_serial->availableForWrite()) {
_serial->write((uint8_t)*buf);
}
_serial->flush();
/* HardwareSerial class funcs do not return any UART errors, sadly */
return MB_OK;
}
MB_StatusTypeDef ArduinoSerial_Rx(void* serial, uint16_t* buf, uint8_t* len, uint8_t* timeout)
{
HardwareSerial* _serial = static_cast<HardwareSerial*>(serial);
buf = _serial->read();
/* HardwareSerial class funcs do not return any UART errors, sadly */
return MB_OK;
}
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