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- Enum-based TX enable mode #300

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0141b93
- Enum-based TX enable mode
lmartorella Aug 2, 2023
40bbc5f
- Added compatibility functions
lmartorella Oct 14, 2023
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6 changes: 3 additions & 3 deletions documentation/API.md
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Original file line number Diff line number Diff line change
Expand Up @@ -47,12 +47,12 @@ bool removeIreg(uint16_t offset, uint16_t numregs = 1);
### Modbus RTU Specific API

```c
bool begin(SoftwareSerial* port, int16_t txEnablePin=-1, bool txEnableDirect=true);
bool begin(HardwareSerial* port, int16_t txEnablePin=-1, bool txEnableDirect=true);
bool begin(SoftwareSerial* port, int16_t txEnablePin=-1, ModbusRTUTxEnableMode txEnableMode=TxEnableHigh);
bool begin(HardwareSerial* port, int16_t txEnablePin=-1, ModbusRTUTxEnableMode txEnableMode=TxEnableHigh);
bool begin(Stream* port);
```

Assing Serial port. txEnablePin controls transmit enable for MAX-485. Pass txEnableDirect=false if txEnablePin uses inverse logic.
Assign Serial port. `txEnablePin` controls transmit enable for MAX-485. Use `txEnableMode = TxEnableLow` if `txEnablePin` uses inverse logic (low when transmitting).

```c
void setBaudrte(uint32 baud);
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6 changes: 3 additions & 3 deletions examples/RTU/README.MD
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Expand Up @@ -11,14 +11,14 @@ This example introduces how to use the library for ModbusRTU (typicaly over RS-4
## Modbus RTU Specific API

```c
bool begin(SoftwareSerial* port, int16_t txEnablePin=-1, bool txEnableDirect=true);
bool begin(HardwareSerial* port, int16_t txEnablePin=-1, bool txEnableDirect=true);
bool begin(SoftwareSerial* port, int16_t txEnablePin=-1, ModbusRTUTxEnableMode txEnableMode=TxEnableHigh);
bool begin(HardwareSerial* port, int16_t txEnablePin=-1, ModbusRTUTxEnableMode txEnableMode=TxEnableHigh);
bool begin(Stream* port);
```

- `port` Pointer to Serial port
- `txEnablePin` RX/TX control pin. Not assigned (assume auto RX/TX) by default
- `txEnableDirect` Direct (true, default) or inverse (false) RX/TX pin control.
- `txEnablePin` controls transmit enable for MAX-485. Use `txEnableMode = TxEnableLow` if `txEnablePin` uses inverse logic (low when transmitting).

Assign Serial port. txEnablePin controls transmit enable for MAX-485.

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18 changes: 9 additions & 9 deletions src/ModbusRTU.cpp
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Expand Up @@ -109,17 +109,17 @@ void ModbusRTUTemplate::setInterFrameTime(uint32_t t_us) {
_t = t_us;
}

bool ModbusRTUTemplate::begin(Stream* port, int16_t txEnablePin, bool txEnableDirect) {
bool ModbusRTUTemplate::begin(Stream* port, int16_t txEnablePin, ModbusRTUTxEnableMode txEnableMode) {
_port = port;
_t = 1750UL;
#if defined(MODBUSRTU_FLUSH_DELAY)
_t1 = charSendTime(0);
#endif
if (txEnablePin >= 0) {
_txEnablePin = txEnablePin;
_direct = txEnableDirect;
_txEnableMode = txEnableMode;
pinMode(_txEnablePin, OUTPUT);
digitalWrite(_txEnablePin, _direct?LOW:HIGH);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
}
return true;
}
Expand All @@ -136,16 +136,16 @@ bool ModbusRTUTemplate::rawSend(uint8_t slaveId, uint8_t* frame, uint8_t len) {
#if defined(MODBUSRTU_REDE)
if (_txEnablePin >= 0 || _rxPin >= 0) {
if (_txEnablePin >= 0)
digitalWrite(_txEnablePin, _direct?HIGH:LOW);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? HIGH : LOW);
if (_rxPin >= 0)
digitalWrite(_rxPin, _direct?HIGH:LOW);
digitalWrite(_rxPin, _txEnableMode == TxEnableHigh ? HIGH : LOW);
#if !defined(ESP32)
delayMicroseconds(MODBUSRTU_REDE_SWITCH_US);
#endif
}
#else
if (_txEnablePin >= 0) {
digitalWrite(_txEnablePin, _direct?HIGH:LOW);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? HIGH : LOW);
#if !defined(ESP32)
delayMicroseconds(MODBUSRTU_REDE_SWITCH_US);
#endif
Expand All @@ -165,16 +165,16 @@ bool ModbusRTUTemplate::rawSend(uint8_t slaveId, uint8_t* frame, uint8_t len) {
delayMicroseconds(_t1 * MODBUSRTU_FLUSH_DELAY);
#endif
if (_txEnablePin >= 0)
digitalWrite(_txEnablePin, _direct?LOW:HIGH);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
if (_rxPin >= 0)
digitalWrite(_rxPin, _direct?LOW:HIGH);
digitalWrite(_rxPin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
}
#else
if (_txEnablePin >= 0) {
#if defined(MODBUSRTU_FLUSH_DELAY)
delayMicroseconds(_t1 * MODBUSRTU_FLUSH_DELAY);
#endif
digitalWrite(_txEnablePin, _direct?LOW:HIGH);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
}
#endif
return true;
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55 changes: 45 additions & 10 deletions src/ModbusRTU.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,14 +8,29 @@
#pragma once
#include "ModbusAPI.h"

/**
* When the TX enable pin is used, specifies the logical level to enable the TX
*/
enum ModbusRTUTxEnableMode {
/**
* The TX enable pin should be high when transmitting
*/
TxEnableHigh,

/**
* The TX enable pin should be low when transmitting
*/
TxEnableLow
};

class ModbusRTUTemplate : public Modbus {
protected:
Stream* _port;
int16_t _txEnablePin = -1;
#if defined(MODBUSRTU_REDE)
int16_t _rxPin = -1;
#endif
bool _direct = true; // Transmit control logic (true=txEnableDirect, false=inverse)
ModbusRTUTxEnableMode _txEnableMode = TxEnableHigh; // Transmit control logic
uint32_t _t; // inter-frame delay in uS
#if defined(MODBUSRTU_FLUSH_DELAY)
uint32_t _t1; // char send time
Expand Down Expand Up @@ -46,13 +61,33 @@ class ModbusRTUTemplate : public Modbus {
uint32_t calculateMinimumInterFrameTime(uint32_t baud, uint8_t char_bits = 11);
void setInterFrameTime(uint32_t t_us);
uint32_t charSendTime(uint32_t baud, uint8_t char_bits = 11);

// Use `ModbusRTUTxEnableMode` overload instead
template <class T>
bool begin(T* port, int16_t txEnablePin = -1, bool txEnableDirect = true);
[[deprecated]]
bool begin(T* port, int16_t txEnablePin = -1, bool txEnableDirect = true) {
return begin(port, txEnablePin, txEnableDirect ? TxEnableHigh : TxEnableLow);
}
template <class T>
bool begin(T* port, int16_t txEnablePin = -1, ModbusRTUTxEnableMode txEnableMode = TxEnableHigh);

#if defined(MODBUSRTU_REDE)
// Use `ModbusRTUTxEnableMode` overload instead
template <class T>
bool begin(T* port, int16_t txEnablePin, int16_t rxEnablePin, bool txEnableDirect);
[[deprecated]]
bool begin(T* port, int16_t txEnablePin, int16_t rxEnablePin, bool txEnableDirect) {
return begin(port, txEnablePin, rxEnablePin, txEnableDirect ? TxEnableHigh : TxEnableLow);
}
template <class T>
bool begin(T* port, int16_t txEnablePin, int16_t rxEnablePin, ModbusRTUTxEnableMode txEnableMode);
#endif
bool begin(Stream* port, int16_t txEnablePin = -1, bool txEnableDirect = true);
// Use `ModbusRTUTxEnableMode` overload instead
[[deprecated]]
bool begin(Stream* port, int16_t txEnablePin = -1, bool txEnableDirect = true) {
return begin(port, txEnablePin, txEnableDirect ? TxEnableHigh : TxEnableLow);
}
bool begin(Stream* port, int16_t txEnablePin = -1, ModbusRTUTxEnableMode txEnableMode = TxEnableHigh);

void task();
void client() { isMaster = true; };
inline void master() {client();}
Expand All @@ -64,7 +99,7 @@ class ModbusRTUTemplate : public Modbus {
};

template <class T>
bool ModbusRTUTemplate::begin(T* port, int16_t txEnablePin, bool txEnableDirect) {
bool ModbusRTUTemplate::begin(T* port, int16_t txEnablePin, ModbusRTUTxEnableMode txEnableMode) {
uint32_t baud = 0;
#if defined(ESP32) || defined(ESP8266) // baudRate() only available with ESP32+ESP8266
baud = port->baudRate();
Expand All @@ -78,20 +113,20 @@ bool ModbusRTUTemplate::begin(T* port, int16_t txEnablePin, bool txEnableDirect)
_port = port;
if (txEnablePin >= 0) {
_txEnablePin = txEnablePin;
_direct = txEnableDirect;
_txEnableMode = txEnableMode;
pinMode(_txEnablePin, OUTPUT);
digitalWrite(_txEnablePin, _direct?LOW:HIGH);
digitalWrite(_txEnablePin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
}
return true;
}
#if defined(MODBUSRTU_REDE)
template <class T>
bool ModbusRTUTemplate::begin(T* port, int16_t txEnablePin, int16_t rxEnablePin, bool txEnableDirect) {
begin(port, txEnablePin, txEnableDirect);
bool ModbusRTUTemplate::begin(T* port, int16_t txEnablePin, int16_t rxEnablePin, ModbusRTUTxEnableMode txEnableMode) {
begin(port, txEnablePin, txEnableMode);
if (rxEnablePin > 0) {
_rxPin = rxEnablePin;
pinMode(_rxPin, OUTPUT);
digitalWrite(_rxPin, _direct?LOW:HIGH);
digitalWrite(_rxPin, _txEnableMode == TxEnableHigh ? LOW : HIGH);
}
}
#endif
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