First stage is read DS18S20 Temperature sensor via Arduino.
Next add to Arduino ModBus.
Here is test equipment and sketch work via Serial Monitor.
DS18S20 Temperature sensor is connected to PIN10 Arduino board.
Arduino DS18S20 library:
https://www.pjrc.com/teensy/td_libs_OneWire.html
Arduino sketch:
#include <OneWire.h>
// OneWire DS18S20, DS18B20, DS1822 Temperature Example
//
// http://www.pjrc.com/teensy/td_libs_OneWire.html
//
// The DallasTemperature library can do all this work for you!
// http://milesburton.com/Dallas_Temperature_Control_Library
OneWire ds(10); // on pin 10 (a 4.7K resistor is necessary)
void setup(void) {
Serial.begin(9600);
}
void loop(void) {
byte i;
byte present = 0;
byte type_s;
byte data[12];
byte addr[8];
float celsius, fahrenheit;
if ( !ds.search(addr)) {
Serial.println("No more addresses.");
Serial.println();
ds.reset_search();
delay(250);
return;
}
Serial.print("ROM =");
for( i = 0; i < 8; i++) {
Serial.write(' ');
Serial.print(addr[i], HEX);
}
if (OneWire::crc8(addr, 7) != addr[7]) {
Serial.println("CRC is not valid!");
return;
}
Serial.println();
// the first ROM byte indicates which chip
switch (addr[0]) {
case 0x10:
Serial.println(" Chip = DS18S20"); // or old DS1820
type_s = 1;
break;
case 0x28:
Serial.println(" Chip = DS18B20");
type_s = 0;
break;
case 0x22:
Serial.println(" Chip = DS1822");
type_s = 0;
break;
default:
Serial.println("Device is not a DS18x20 family device.");
return;
}
ds.reset();
ds.select(addr);
ds.write(0x44, 1); // start conversion, with parasite power on at the end
delay(1000); // maybe 750ms is enough, maybe not
// we might do a ds.depower() here, but the reset will take care of it.
present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad
Serial.print(" Data = ");
Serial.print(present, HEX);
Serial.print(" ");
for ( i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();
Serial.print(data[i], HEX);
Serial.print(" ");
}
Serial.print(" CRC=");
Serial.print(OneWire::crc8(data, 8), HEX);
Serial.println();
// Convert the data to actual temperature
// because the result is a 16 bit signed integer, it should
// be stored to an "int16_t" type, which is always 16 bits
// even when compiled on a 32 bit processor.
int16_t raw = (data[1] << 8) | data[0];
if (type_s) {
raw = raw << 3; // 9 bit resolution default
if (data[7] == 0x10) {
// "count remain" gives full 12 bit resolution
raw = (raw & 0xFFF0) + 12 - data[6];
}
} else {
byte cfg = (data[4] & 0x60);
// at lower res, the low bits are undefined, so let's zero them
if (cfg == 0x00) raw = raw & ~7; // 9 bit resolution, 93.75 ms
else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
//// default is 12 bit resolution, 750 ms conversion time
}
celsius = (float)raw / 16.0;
fahrenheit = celsius * 1.8 + 32.0;
Serial.print(" Temperature = ");
Serial.print(celsius);
Serial.print(" Celsius, ");
Serial.print(fahrenheit);
Serial.println(" Fahrenheit");
}
ROM = 28 B2 9C 24 7 0 0 E5 Chip = DS18B20 Data = 1 D5 1 4B 46 7F FF B 10 42 CRC=42 Temperature = 29.31 Celsius, 84.76 Fahrenheit No more addresses. ROM = 28 B2 9C 24 7 0 0 E5 Chip = DS18B20 Data = 1 D5 1 4B 46 7F FF B 10 42 CRC=42 Temperature = 29.31 Celsius, 84.76 Fahrenheit No more addresses. ...... ... ...
Arduino ModBus library:
https://github.com/smarmengol/Modbus-Master-Slave-for-Arduino
Arduino sketch:
/**
* Modbus slave example 2:
* The purpose of this example is to link a data array
* from the Arduino to an external device.
*
* Recommended Modbus Master: modpoll
* http://www.modbusdriver.com/modpoll.html
*/
#include <ModbusRtu.h>
#include <OneWire.h>
OneWire ds(10); // on pin 10 (a 4.7K resistor is necessary)
// data array for modbus network sharing
uint16_t au16data[16] = {
3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1 };
/**
* Modbus object declaration
* u8id : node id = 0 for master, = 1..247 for slave
* u8serno : serial port (use 0 for Serial)
* u8txenpin : 0 for RS-232 and USB-FTDI
* or any pin number > 1 for RS-485
*/
Modbus slave(1,0,0); // this is slave @1 and RS-232 or USB-FTDI
byte i;
byte present = 0;
byte type_s;
byte data[12];
byte addr[8];
float celsius, fahrenheit;
void setup() {
slave.begin( 19200, SERIAL_8E1 ); // 19200 baud, 8-bits, even, 1-bit stop
}
void loop() {
union {
float f;
byte b[4];
} fn;
Read_DS1820();
fn.f = celsius;
au16data[0] = fn.b[1]*256 + fn.b[0];
au16data[1] = fn.b[3]*256 + fn.b[2];
slave.poll( au16data, 16 );
}
void Read_DS1820() {
if ( !ds.search(addr)) {
//Serial.println("No more addresses.");
//Serial.println();
//ds.reset_search();
//delay(250);
return;
}
//Serial.print("ROM =");
for( i = 0; i < 8; i++) {
//Serial.write(' ');
//Serial.print(addr[i], HEX);
}
if (OneWire::crc8(addr, 7) != addr[7]) {
//Serial.println("CRC is not valid!");
return;
}
//Serial.println();
// the first ROM byte indicates which chip
switch (addr[0]) {
case 0x10:
//Serial.println(" Chip = DS18S20"); // or old DS1820
type_s = 1;
break;
case 0x28:
//Serial.println(" Chip = DS18B20");
type_s = 0;
break;
case 0x22:
//Serial.println(" Chip = DS1822");
type_s = 0;
break;
default:
//Serial.println("Device is not a DS18x20 family device.");
return;
}
ds.reset();
ds.select(addr);
ds.write(0x44, 1); // start conversion, with parasite power on at the end
//delay(1000); // maybe 750ms is enough, maybe not
// we might do a ds.depower() here, but the reset will take care of it.
present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad
//Serial.print(" Data = ");
//Serial.print(present, HEX);
//Serial.print(" ");
for ( i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();
//Serial.print(data[i], HEX);
//Serial.print(" ");
}
//Serial.print(" CRC=");
//Serial.print(OneWire::crc8(data, 8), HEX);
//Serial.println();
// Convert the data to actual temperature
// because the result is a 16 bit signed integer, it should
// be stored to an "int16_t" type, which is always 16 bits
// even when compiled on a 32 bit processor.
int16_t raw = (data[1] << 8) | data[0];
if (type_s) {
raw = raw << 3; // 9 bit resolution default
if (data[7] == 0x10) {
// "count remain" gives full 12 bit resolution
raw = (raw & 0xFFF0) + 12 - data[6];
}
} else {
byte cfg = (data[4] & 0x60);
// at lower res, the low bits are undefined, so let's zero them
if (cfg == 0x00) raw = raw & ~7; // 9 bit resolution, 93.75 ms
else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
//// default is 12 bit resolution, 750 ms conversion time
}
celsius = (float)raw / 16.0;
fahrenheit = celsius * 1.8 + 32.0;
//Serial.print(" Temperature = ");
//Serial.print(celsius);
//Serial.print(" Celsius, ");
//Serial.print(fahrenheit);
//Serial.println(" Fahrenheit");
}
