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Allow customizable modbus timeout #178

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Allow customizable modbus timeout #178

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b5b3757
Allow customizable modbus timeout
samc1213 Sep 28, 2022
282e68d
Update README
samc1213 Sep 28, 2022
10d0e14
Fix Build
samc1213 Sep 28, 2022
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4 changes: 2 additions & 2 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -105,8 +105,8 @@ void setup()
// use Serial (port 0); initialize Modbus communication baud rate
Serial.begin(19200);

// communicate with Modbus slave ID 2 over Serial (port 0)
node.begin(2, Serial);
// communicate with Modbus slave ID 2 over Serial (port 0), with a 1-second timeout
node.begin(2, Serial, 1000);
}


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6 changes: 4 additions & 2 deletions src/ModbusMaster.cpp
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Expand Up @@ -56,13 +56,15 @@ Call once class has been instantiated, typically within setup().

@param slave Modbus slave ID (1..255)
@param &serial reference to serial port object (Serial, Serial1, ... Serial3)
@param u16MBResponseTimeout Modbus timeout in milliseconds (default 2000)
@ingroup setup
*/
void ModbusMaster::begin(uint8_t slave, Stream &serial)
void ModbusMaster::begin(uint8_t slave, Stream &serial, uint16_t u16MBResponseTimeout = ModbusMaster::ku16MBResponseTimeout)
{
// txBuffer = (uint16_t*) calloc(ku8MaxBufferSize, sizeof(uint16_t));
_u8MBSlave = slave;
_serial = &serial;
_u16MBResponseTimeout = u16MBResponseTimeout;
_u8TransmitBufferIndex = 0;
u16TransmitBufferLength = 0;

Expand Down Expand Up @@ -797,7 +799,7 @@ uint8_t ModbusMaster::ModbusMasterTransaction(uint8_t u8MBFunction)
break;
}
}
if ((millis() - u32StartTime) > ku16MBResponseTimeout)
if ((millis() - u32StartTime) > _u16MBResponseTimeout)
{
u8MBStatus = ku8MBResponseTimedOut;
}
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7 changes: 4 additions & 3 deletions src/ModbusMaster.h
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Expand Up @@ -71,7 +71,7 @@ class ModbusMaster
public:
ModbusMaster();

void begin(uint8_t, Stream &serial);
void begin(uint8_t, Stream &serial, uint16_t u16MBResponseTimeout);
void idle(void (*)());
void preTransmission(void (*)());
void postTransmission(void (*)());
Expand Down Expand Up @@ -219,6 +219,7 @@ class ModbusMaster

private:
Stream* _serial; ///< reference to serial port object
uint16_t _u16MBResponseTimeout; ///< Modbus timeout [milliseconds]
uint8_t _u8MBSlave; ///< Modbus slave (1..255) initialized in begin()
static const uint8_t ku8MaxBufferSize = 64; ///< size of response/transmit buffers
uint16_t _u16ReadAddress; ///< slave register from which to read
Expand Down Expand Up @@ -248,8 +249,8 @@ 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

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

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