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Add Modbus function 0x2B/0E Read DeviceIdentifiers, add get/set SlaveID, get/set ResponseTimeout, get . #185

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Add Modbus function 0x2B/0E Read DeviceIdentifiers, add get/set SlaveID, get/set ResponseTimeout, get . #185

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ac85132
before doing any changes, we have to do some cleaning up by removing …
rob040 Feb 20, 2023
ec536ec
Comment out unused/unwanted public function requestFrom(); it was alr…
rob040 Feb 20, 2023
19f2700
Remove commented-out functions.
rob040 Feb 20, 2023
3ef6b44
Add method to change/request (get/set) the SlaveID.
rob040 Feb 20, 2023
148e400
Fix value returned by getResponseSize(), and usage of available() and…
rob040 Feb 22, 2023
01baa9c
increase library version; still backwards compatible
rob040 Feb 22, 2023
16d5f1f
Merge branch 'master' of github.com:rob040/ModbusMaster
rob040 Feb 22, 2023
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Add method to change/request (get/set) the SlaveID. 
Add method to change/request (get/set) the ResponseTimeout.
Add method to request the response size of data in the response buffer.
Add Modbus function 0x2B/0E Read DeviceIdentifiers ku8MBReadDeviceIdentifiers.
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@rob040
rob040 committed Feb 20, 2023
commit 3ef6b4482f7a3b001b9b8dd8b9c17cd299c5de78
116 changes: 114 additions & 2 deletions src/ModbusMaster.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@ ModbusMaster::ModbusMaster(void)
_idle = 0;
_preTransmission = 0;
_postTransmission = 0;
_u16ResponseTimeout = ku16MBDefaultResponseTimeout;
}

/**
Expand Down Expand Up @@ -183,6 +184,7 @@ void ModbusMaster::postTransmission(void (*postTransmission)())
Retrieve data from response buffer.

@see ModbusMaster::clearResponseBuffer()
@see ModbusMaster::getResponseSize()
@param u8Index index of response buffer array (0x00..0x3F)
@return value in position u8Index of response buffer (0x0000..0xFFFF)
@ingroup buffer
Expand All @@ -199,6 +201,17 @@ uint16_t ModbusMaster::getResponseBuffer(uint8_t u8Index)
}
}

/**
Get number of words in response buffer.

@see ModbusMaster::getResponseBuffer
@return value in position u8Index of response buffer (0x0000..0xFFFF)
@ingroup buffer
*/
uint8_t ModbusMaster::getResponseSize()
{
return _u8ResponseBufferLength;
}

/**
Clear Modbus response buffer.
Expand Down Expand Up @@ -254,6 +267,41 @@ void ModbusMaster::clearTransmitBuffer()
}
}

/**
* Set Modbus save id
* Change the slave id that is set with begin method.
* */
void ModbusMaster::setSlaveId(uint8_t slaveid)
{
_u8MBSlave = slaveid;
}

/**
* Get Modbus save id
* */
uint8_t ModbusMaster::getSlaveId(void)
{
return _u8MBSlave;
}


/**
Get the response timeout. Value is in ms.
*/
uint16_t ModbusMaster::getResponseTimeout()
{
return _u16ResponseTimeout;
}

/**
Sets the response timeout. Value should be given in ms.
The default is 2000 ms.
*/
void ModbusMaster::setResponseTimeout(uint16_t timeout)
{
_u16ResponseTimeout = timeout;
}


/**
Modbus function 0x01 Read Coils.
Expand Down Expand Up @@ -533,6 +581,18 @@ uint8_t ModbusMaster::readWriteMultipleRegisters(uint16_t u16ReadAddress,
return ModbusMasterTransaction(ku8MBReadWriteMultipleRegisters);
}

/*
* ku8MBReadDeviceIdentifiers = 0x2B/0E
*/
//uint8_t ModbusMaster::readDeviceIdentifiers(uint8_t ObjectId)
uint8_t ModbusMaster::readDeviceIdentifiers(uint8_t ReadId, uint8_t ObjectId, char *pu8ReadStrBuffer, uint8_t u8ReadStrBufferMaxSize, uint8_t *pu8ReadStrSize)
{
_u16ReadAddress = ((uint16_t)ReadId << 8) | ObjectId;
_pu8ReadStrBuffer = pu8ReadStrBuffer;
_u8ReadStrBufferMaxSize = u8ReadStrBufferMaxSize;
_pu8ReadStrSize = pu8ReadStrSize;
return ModbusMasterTransaction(ku8MBReadDeviceIdentifiers);
}

/* _____PRIVATE FUNCTIONS____________________________________________________ */
/**
Expand All @@ -553,6 +613,8 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
uint8_t u8ModbusADU[256];
uint8_t u8ModbusADUSize = 0;
uint8_t i, u8Qty;
uint8_t u8RDIobjcnt = 0;
uint8_t u8RDInextObjSzIdx = 255;
uint16_t u16CRC;
uint32_t u32StartTime;
uint8_t u8BytesLeft = 8;
Expand All @@ -574,6 +636,14 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
u8ModbusADU[u8ModbusADUSize++] = highByte(_u16ReadQty);
u8ModbusADU[u8ModbusADUSize++] = lowByte(_u16ReadQty);
break;
case ku8MBReadDeviceIdentifiers:
//u8ModbusADUSize = 0;
//u8ModbusADU[u8ModbusADUSize++] = u8MBFunction;
u8ModbusADU[u8ModbusADUSize++] = 0x0E; // MEI type
u8ModbusADU[u8ModbusADUSize++] = highByte(_u16ReadAddress); // ReadId code
u8ModbusADU[u8ModbusADUSize++] = lowByte(_u16ReadAddress); // ObjectId code
u8BytesLeft = 12;
break;
}

switch(u8MBFunction)
Expand Down Expand Up @@ -730,7 +800,7 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
}

// evaluate slave ID, function code once enough bytes have been read
if (u8ModbusADUSize == 5)
if ((u8ModbusADUSize == 5) && (u8ModbusADU[1] != ku8MBReadDeviceIdentifiers))
{
// verify response is for correct Modbus slave
if (u8ModbusADU[0] != _u8MBSlave)
Expand Down Expand Up @@ -774,9 +844,27 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
case ku8MBMaskWriteRegister:
u8BytesLeft = 5;
break;
break;
}
}
if (u8ModbusADU[1] == ku8MBReadDeviceIdentifiers) // function 2B-0E
{
if ((u8ModbusADUSize == 8) && (u8RDIobjcnt == 0))
{
u8RDIobjcnt = u8ModbusADU[7];
u8BytesLeft = u8RDIobjcnt * 2 + 2;
u8RDInextObjSzIdx = u8ModbusADUSize + 2;
}
if ((u8ModbusADUSize == u8RDInextObjSzIdx) && (u8RDIobjcnt != 0))
{
u8BytesLeft += u8ModbusADU[u8ModbusADUSize - 1];
if (--u8RDIobjcnt != 0)
{
u8RDInextObjSzIdx += u8ModbusADU[u8ModbusADUSize - 1] + 2;
}
}
}
if ((millis() - u32StartTime) > ku16MBResponseTimeout)
if ((millis() - u32StartTime) > _u16ResponseTimeout)
{
u8MBStatus = ku8MBResponseTimedOut;
}
Expand Down Expand Up @@ -878,6 +966,30 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
_u8ResponseBufferLength = i;
}
break;
case ku8MBReadDeviceIdentifiers:
// The payload data of this function is a linked list of mostly ascii strings
// Here we concatenate the passed device ID strings, separated by spaces, and return to the caller.
u8RDIobjcnt = u8ModbusADU[7];
u8RDInextObjSzIdx = 7 + 2;
*_pu8ReadStrSize = 0;
_u8ResponseBufferIndex = 0;
for (i = 0; i < u8RDIobjcnt; i++)
{
int len = u8ModbusADU[u8RDInextObjSzIdx];
if ((len > 2) && (_u8ResponseBufferIndex + len < _u8ReadStrBufferMaxSize))
{
if (_u8ResponseBufferIndex > 0)
{
_pu8ReadStrBuffer[_u8ResponseBufferIndex++] = ' ';
}
memcpy(_pu8ReadStrBuffer + _u8ResponseBufferIndex, u8ModbusADU + u8RDInextObjSzIdx + 1, len);
_u8ResponseBufferIndex += len;
_pu8ReadStrBuffer[_u8ResponseBufferIndex] = 0;
}
u8RDInextObjSzIdx += len + 2;
*_pu8ReadStrSize = _u8ResponseBufferIndex;
}
break;
}
}

Expand Down
15 changes: 14 additions & 1 deletion src/ModbusMaster.h
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Original file line number Diff line number Diff line change
Expand Up @@ -232,9 +232,14 @@ class ModbusMaster
static const uint8_t ku8MBInvalidCRC = 0xE3;

uint16_t getResponseBuffer(uint8_t Index);
uint8_t getResponseSize(void);
void clearResponseBuffer(void);
uint8_t setTransmitBuffer(uint8_t Offset, uint16_t Value);
void clearTransmitBuffer(void);
void setSlaveId(uint8_t slaveid);
uint8_t getSlaveId(void);
uint16_t getResponseTimeout(void);
void setResponseTimeout(uint16_t timeout_ms);

void beginTransmission(uint16_t u16Address);
//uint8_t requestFrom(uint16_t Addr, uint16_t Qty);
Expand All @@ -258,6 +263,8 @@ class ModbusMaster
uint8_t maskWriteRegister(uint16_t u16WriteAddress, uint16_t u16AndMask, uint16_t u16OrMask);
uint8_t readWriteMultipleRegisters(uint16_t u16ReadAddress, uint16_t u16ReadQty, uint16_t u16WriteAddress, uint16_t u16WriteQty);
uint8_t readWriteMultipleRegisters(uint16_t Addr, uint16_t Qty);
//uint8_t readDeviceIdentifiers(uint8_t ReadId, uint8_t ObjectId);
uint8_t readDeviceIdentifiers(uint8_t ReadId, uint8_t ObjectId, char *pu8ReadStrBuffer, uint8_t u8ReadStrBufferMaxSize, uint8_t *pu8ReadStrSize);

private:
Stream* _serial; ///< reference to serial port object
Expand All @@ -273,6 +280,10 @@ class ModbusMaster
uint16_t u16TransmitBufferLength;
uint8_t _u8ResponseBufferIndex;
uint8_t _u8ResponseBufferLength;
char *_pu8ReadStrBuffer;
uint8_t _u8ReadStrBufferMaxSize;
uint8_t *_pu8ReadStrSize;
uint16_t _u16ResponseTimeout;

// Modbus function codes for bit access
static const uint8_t ku8MBReadCoils = 0x01; ///< Modbus function 0x01 Read Coils
Expand All @@ -288,8 +299,10 @@ class ModbusMaster
static const uint8_t ku8MBMaskWriteRegister = 0x16; ///< Modbus function 0x16 Mask Write Register
static const uint8_t ku8MBReadWriteMultipleRegisters = 0x17; ///< Modbus function 0x17 Read Write Multiple Registers

static const uint8_t ku8MBReadDeviceIdentifiers = 0x2B; ///< Modbus function 0x2B/0E Read DeviceIdentifiers

// Modbus timeout [milliseconds]
static const uint16_t ku16MBResponseTimeout = 2000; ///< Modbus timeout [milliseconds]
static const uint16_t ku16MBDefaultResponseTimeout = 2000; ///< Modbus timeout [milliseconds]

// master function that conducts Modbus transactions
uint8_t ModbusMasterTransaction(uint8_t u8MBFunction);
Expand Down