Functions
boolean	Modbus::getTimeOutState ()
	get communication watch-dog timer state More...

int8_t	Modbus::poll ()
	cyclic poll for master More...

int8_t	Modbus::poll (uint16_t *regs, uint8_t u8size)
	cyclic poll for slave More...

int8_t	Modbus::query (modbus_t telegram)
	only for master More...

Detailed Description

Function Documentation

◆ getTimeOutState()

boolean Modbus::getTimeOutState ( )

get communication watch-dog timer state

Return communication Watchdog state. It could be useful to reset outputs if the watchdog is fired.

Returns: TRUE if millis() > u32timeOut

Definition at line 506 of file ModbusRtu.h.

 {
     return (millis() > u32timeOut);
 }

◆ poll() [1/2]

int8_t Modbus::poll ( )

cyclic poll for master

*** Only for Modbus Master *** This method checks if there is any incoming answer if pending. If there is no answer, it would change Master state to COM_IDLE. This method must be called only at loop section. Avoid any delay() function.

Any incoming data would be redirected to au16regs pointer, as defined in its modbus_t query telegram.

@params nothing

Returns: errors counter

Definition at line 691 of file ModbusRtu.h.

 {
     // check if there is any incoming frame
     uint8_t u8current;
     if (u8serno < 4)
     {
         u8current = port->available();
     }
     else
     {
         u8current = softPort->available();
     }
  
     if (millis() > u32timeOut)
     {
         u8state = COM_IDLE;
         u8lastError = NO_REPLY;
         u16errCnt++;
         return 0;
     }
  
     if (u8current == 0)
     {
         return 0;
     }
  
     // check T35 after frame end or still no frame end
     if (u8current != u8lastRec)
     {
         u8lastRec = u8current;
         u32time = millis() + T35;
         return 0;
     }
     if (millis() < u32time)
     {
         return 0;
     };
  
     // transfer Serial buffer frame to auBuffer
     u8lastRec = 0;
     int8_t i8state = getRxBuffer();
     if (i8state < 7)
     {
         u8state = COM_IDLE;
         u16errCnt++;
         Log.verboseln("Add error : %d - RX-Buffer < 7", i8state);
         printHex(rxBuffer, u8BufferSize);
         return i8state;
     }
  
     // validate message: id, CRC, FCT, exception
     uint8_t u8exception = validateAnswer();
     if (u8exception != 0)
     {
         Log.verboseln("ModbusRTU::poll : exception : %d", u8exception);
         u8state = COM_IDLE;
         return u8exception;
     }
  
     // process answer
     switch (au8Buffer[FUNC])
     {
     case MB_FC_READ_COILS:
     case MB_FC_READ_DISCRETE_INPUT:
         // call get_FC1 to transfer the incoming message to au16regs buffer
         get_FC1();
         break;
     case MB_FC_READ_INPUT_REGISTER:
     case MB_FC_READ_REGISTERS:
         // call get_FC3 to transfer the incoming message to au16regs buffer
         get_FC3();
         break;
     case MB_FC_WRITE_COIL:
     case MB_FC_WRITE_REGISTER:
     case MB_FC_WRITE_MULTIPLE_COILS:
     case MB_FC_WRITE_MULTIPLE_REGISTERS:
         // nothing to do
         break;
     default:
         break;
     }
     u8state = COM_IDLE;
     currentQuery->flags = QUERY_STATE::RESPONDED;
     return u8BufferSize;
 }

◆ poll() [2/2]

int8_t Modbus::poll	(	uint16_t *	regs,
		uint8_t	u8size
	)

cyclic poll for slave

*** Only for Modbus Slave *** This method checks if there is any incoming query Afterwards, it would shoot a validation routine plus a register query Avoid any delay() function !!!! After a successful frame between the Master and the Slave, the time-out timer is reset.

Parameters

*regs	register table for communication exchange
u8size	size of the register table

Returns: 0 if no query, 1..4 if communication error, >4 if correct query processed

Definition at line 790 of file ModbusRtu.h.

 {
  
     au16regs = regs;
     u8regsize = u8size;
     uint8_t u8current;
  
     // check if there is any incoming frame
     if (u8serno < 4)
         u8current = port->available();
     else
         u8current = softPort->available();
  
     if (u8current == 0)
         return 0;
  
     // check T35 after frame end or still no frame end
     if (u8current != u8lastRec)
     {
         u8lastRec = u8current;
         u32time = millis() + T35;
         return 0;
     }
     if (millis() < u32time)
         return 0;
  
     u8lastRec = 0;
     int8_t i8state = getRxBuffer();
     u8lastError = i8state;
     if (i8state < 7)
         return i8state;
  
     // check slave id
     if (au8Buffer[ID] != u8id)
     {
         return 0;
     }
  
     // validate message: CRC, FCT, address and size
     uint8_t u8exception = validateRequest();
     if (u8exception > 0)
     {
         Serial.println("exception : 1");
         if (u8exception != NO_REPLY)
         {
             buildException(u8exception);
             sendTxBuffer();
         }
         u8lastError = u8exception;
         return u8exception;
     }
  
     u32timeOut = millis() + long(u16timeOut);
     u8lastError = 0;
  
     Log.verboseln("mb : process message : %d", FUNC);
  
     // process message
     switch (au8Buffer[FUNC])
     {
     case MB_FC_READ_COILS:
     case MB_FC_READ_DISCRETE_INPUT:
         return process_FC1(regs, u8size);
         break;
     case MB_FC_READ_INPUT_REGISTER:
     case MB_FC_READ_REGISTERS:
         return process_FC3(regs, u8size);
         break;
     case MB_FC_WRITE_COIL:
         return process_FC5(regs, u8size);
         break;
     case MB_FC_WRITE_REGISTER:
         return process_FC6(regs, u8size);
         break;
     case MB_FC_WRITE_MULTIPLE_COILS:
         return process_FC15(regs, u8size);
         break;
     case MB_FC_WRITE_MULTIPLE_REGISTERS:
         return process_FC16(regs, u8size);
         break;
     default:
         break;
     }
     currentQuery->flags = RESPONDED;
     return i8state;
 }

◆ query()

int8_t Modbus::query ( modbus_t telegram )

only for master

*** Only Modbus Master *** Generate a query to an slave with a modbus_t telegram structure The Master must be in COM_IDLE mode. After it, its state would be COM_WAITING. This method has to be called only in loop() section.

See also: modbus_t