function code 02 and 03

Author: bertmelis

src/ModbusMessage.cpp

@@ -132,28 +132,68 @@ ModbusRequest::ModbusRequest(uint8_t length) :
   _address(0),
   _byteCount(0) {}
 
-ModbusRequest04::ModbusRequest04(uint8_t slaveAddress, uint16_t address, uint16_t byteCount) :
+ModbusRequest02::ModbusRequest02(uint8_t slaveAddress, uint16_t address, uint16_t numberCoils) :
+  ModbusRequest(8) {
+  _slaveAddress = slaveAddress;
+  _functionCode = READ_DISCR_INPUT;
+  _address = address;
+  _byteCount = numberCoils / 8 + 1;
+  add(_slaveAddress);
+  add(_functionCode);
+  add(high(_address));
+  add(low(_address));
+  add(high(numberCoils));
+  add(low(numberCoils));
+  uint16_t CRC = CRC16(_buffer, 6);
+  add(low(CRC));
+  add(high(CRC));
+}
+
+size_t ModbusRequest02::responseLength() {
+  return 5 + _byteCount;
+}
+
+ModbusRequest03::ModbusRequest03(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters) :
+  ModbusRequest(12) {
+  _slaveAddress = slaveAddress;
+  _functionCode = READ_HOLD_REGISTER;
+  _address = address;
+  _byteCount = numberRegisters * 2;  // register is 2 bytes wide
+  add(_slaveAddress);
+  add(_functionCode);
+  add(high(_address));
+  add(low(_address));
+  add(high(numberRegisters));
+  add(low(numberRegisters));
+  uint16_t CRC = CRC16(_buffer, 6);
+  add(low(CRC));
+  add(high(CRC));
+}
+
+size_t ModbusRequest03::responseLength() {
+  return 5 + _byteCount;
+}
+
+ModbusRequest04::ModbusRequest04(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters) :
   ModbusRequest(8) {
   _slaveAddress = slaveAddress;
   _functionCode = READ_INPUT_REGISTER;
   _address = address;
-  _byteCount = byteCount;
+  _byteCount = numberRegisters * 2;  // register is 2 bytes wide
   add(_slaveAddress);
   add(_functionCode);
   add(high(_address));
   add(low(_address));
-  add(high(_byteCount));
-  add(low(_byteCount));
+  add(high(numberRegisters));
+  add(low(numberRegisters));
   uint16_t CRC = CRC16(_buffer, 6);
   add(low(CRC));
   add(high(CRC));
 }
 
-ModbusResponse* ModbusRequest04::makeResponse() {
+size_t ModbusRequest04::responseLength() {
   // slaveAddress (1) + functionCode (1) + byteCount (1) + length x 2 + CRC (2)
-  uint8_t responseLength = 3 + (_byteCount * 2) + 2;
-  ModbusResponse* response = new ModbusResponse(responseLength, this);
-  return response;
+  return 5 + _byteCount;
 }
 
 ModbusResponse::ModbusResponse(uint8_t length, ModbusRequest* request) :
@@ -165,9 +205,7 @@ bool ModbusResponse::isComplete() {
   if (_buffer[1] > 0x80 && _index == 4) {  // 4: slaveAddress(1), errorCode(1), CRC(2)
     return true;
   }
-  if (_index > _buffer[2] + 4) {
-    return true;
-  }
+  if (_index == _request->responseLength()) return true;
   return false;
 }
 
@@ -191,7 +229,7 @@ bool ModbusResponse::isSucces() {
 
 bool ModbusResponse::checkCRC() {
   uint16_t CRC = CRC16(_buffer, _length - 2);
-  if (low(CRC) == _buffer[_length - 2] && high(CRC) == _buffer[_length -1 ]) {
+  if (low(CRC) == _buffer[_length - 2] && high(CRC) == _buffer[_length -1]) {
     return true;
   } else {
     return false;

src/ModbusMessage.h

@@ -49,7 +49,7 @@ class ModbusResponse;  // forward declare for use in ModbusRequest
 
 class ModbusRequest : public ModbusMessage {
  public:
-  virtual ModbusResponse* makeResponse() = 0;
+  virtual size_t responseLength() = 0;
 
  protected:
   explicit ModbusRequest(uint8_t length);
@@ -59,10 +59,25 @@ class ModbusRequest : public ModbusMessage {
   uint16_t _byteCount;
 };
 
+// read discrete coils
+class ModbusRequest02 : public ModbusRequest {
+ public:
+  explicit ModbusRequest02(uint8_t slaveAddress, uint16_t address, uint16_t numberCoils);
+  size_t responseLength();
+};
+
+// read holding registers
+class ModbusRequest03 : public ModbusRequest {
+ public:
+  explicit ModbusRequest03(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters);
+  size_t responseLength();
+};
+
+// read input registers
 class ModbusRequest04 : public ModbusRequest {
  public:
-  explicit ModbusRequest04(uint8_t slaveAddress, uint16_t address, uint16_t byteCount);
-  ModbusResponse* makeResponse();
+  explicit ModbusRequest04(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters);
+  size_t responseLength();
 };
 
 class ModbusResponse : public ModbusMessage {

src/esp32ModbusRTU.cpp

@@ -50,8 +50,23 @@ void esp32ModbusRTU::begin() {
   if (_interval == 0) _interval = 1;  // minimum of 1msec interval
 }
 
-bool esp32ModbusRTU::readInputRegister(uint8_t slaveAddress, uint16_t address, uint16_t byteCount) {
-  ModbusRequest* request = new ModbusRequest04(slaveAddress, address, byteCount);
+bool esp32ModbusRTU::readDiscreteInputs(uint8_t slaveAddress, uint16_t address, uint16_t numberCoils) {
+  ModbusRequest* request = new ModbusRequest02(slaveAddress, address, numberCoils);
+  if (xQueueSend(_queue, reinterpret_cast<void*>(&request), (TickType_t)0) != pdPASS) {
+    return false;
+  }
+  return true;
+}
+bool esp32ModbusRTU::readHoldingRegisters(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters) {
+  ModbusRequest* request = new ModbusRequest03(slaveAddress, address, numberRegisters);
+  if (xQueueSend(_queue, reinterpret_cast<void*>(&request), (TickType_t)0) != pdPASS) {
+    return false;
+  }
+  return true;
+}
+
+bool esp32ModbusRTU::readInputRegisters(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters) {
+  ModbusRequest* request = new ModbusRequest04(slaveAddress, address, numberRegisters);
   if (xQueueSend(_queue, reinterpret_cast<void*>(&request), (TickType_t)0) != pdPASS) {
     return false;
   }
@@ -93,7 +108,7 @@ void esp32ModbusRTU::_send(uint8_t* data, uint8_t length) {
 }
 
 ModbusResponse* esp32ModbusRTU::_receive(ModbusRequest* request) {
-  ModbusResponse* response = request->makeResponse();
+  ModbusResponse* response = new ModbusResponse(request->responseLength(), request);
   while (true) {
     while (_serial->available()) {
       response->add(_serial->read());

src/esp32ModbusRTU.h

@@ -51,7 +51,9 @@ class esp32ModbusRTU {
   explicit esp32ModbusRTU(HardwareSerial* serial, int8_t rtsPin = -1);
   ~esp32ModbusRTU();
   void begin();
-  bool readInputRegister(uint8_t slaveAddress, uint16_t address, uint16_t byteCount);
+  bool readDiscreteInputs(uint8_t slaveAddress, uint16_t address, uint16_t numberCoils);
+  bool readHoldingRegisters(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters);
+  bool readInputRegisters(uint8_t slaveAddress, uint16_t address, uint16_t numberRegisters);
   void onData(MBRTUOnData handler);
   void onError(MBOnError handler);
 

src/esp32ModbusTypeDefs.h

@@ -31,7 +31,7 @@ namespace esp32Modbus {
 
 enum MBFunctionCode : uint8_t {
   READ_COIL            = 0x01,
-  READ_DISC_INPUT      = 0x02,
+  READ_DISCR_INPUT     = 0x02,
   READ_HOLD_REGISTER   = 0x03,
   READ_INPUT_REGISTER  = 0x04,
   WRITE_COIL           = 0x05,