====== NT18B07: 7 Kanal RS485 Temperatur Sensor with Modbus RTU ======
{{ :sensor:nt18b07_1.png?160|}}
The NT18B07 is a 7-channel NTC temperature sensor interface board/module that uses the MODBUS RTU communication protocol over an RS485 interface for industrial and automation applications. Requires external **B3950 10K 1% NTC** thermistors

**NT18B07 Description**

  * Operating current ranges from 8 to 13 mA, depending on external connections. 
  * The device supports MODBUS RTU commands using function codes 03 and 06. 
  * By adjusting the R485 address, up to 247 modules can be cascaded; if exceeding 16, an R485 repeater is recommended. 
  * A maximum of 8 temperature sensors can be connected at once. 
  * Temperature measurement spans from -55°C to +125°C (-67°F to +257°F), with an accuracy of ±0.5°C between -10°C and 85°C.
  * Resistance value: 10K
  * Resistance accuracy: ±1%
  * Resistance B value: 3950 ±1%
  * Wire specification: 2651 26# parallel resistance, temperature resistance 105°C
  * Connector model: XH2.54-2P
  * Probe: without mounting holes
  * Supply voltage: 6-24V

===== B3590 10K 1% NTC thermal sensor =====
{{ :sensor:nt18b07_3.png?120|B3590 10K 1% NTC thermal sensor}}
  * Product type: NTC 10K / B3590 1%
  * Temperature range: -50°C to 125°C (-58°F to 257°F)


==== NT18B07 Modbus settings ====
Default settings: SlaveID: 1, 9600 baud, parity: N,8,1

^holding register addresses^Number of registers^Description^Unit^Note|
|0x0|1|CH1 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x1|1|CH2 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x2|1|CH3 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x3|1|CH4 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x4|1|CH5 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x5|1|CH6 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x6|1|CH7 temperature sensor|0.1 °C|0xF555 (-2731): Sensor Error|
|0x8|1|CH1 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0x9|1|CH2 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0xA|1|CH3 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0xB|1|CH4 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0xC|1|CH5 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0xD|1|CH6 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0xE|1|CH7 temperature correction value|0.1 °C|>0: increase, <0: decrease, default:0|
|0x00FD|1|Automatic temperature report|Second|0: (default) query function, 1-255 report time (1 - 10 seconds)|
|0x00FE|1|RS485 address (station address)|-|Read address: 0x00FF, write address 1-247, default: 1|
|0x00FF|1|Baud rate|-|0:1200, 1:2400, 2:4800, 3:9600 (default), 4:19.200, 5: factory reset|

{{page>:tarhal}}

==== Arduino ====
The NT18B07 is a 7-channel NTC thermistor temperature acquisition module that communicates via RS485 Modbus RTU. Unlike the MAX31865 (which is SPI-based), the NT18B07 requires an RS-485-to-TTL converter (e.g., a [[max485|MAX485 module]]) to interface with an Arduino.

**Wiring Diagram**

To connect the NT18B07 to an Arduino Uno using a standard MAX485 module:

  * **NT18B07 A+ to MAX485 A** and **NT18B07 B- to MAX485 B**.
  * **MAX485 VCC/GND:** 5V and GND.
  * **MAX485 RO:** Arduino Pin 2 (RX).
  * **MAX485 DI:** Arduino Pin 3 (TX).
  * **MAX485 DE & RE:** Tied together to Arduino Pin 4 (Direction Control).
  * **NT18B07 Power:** DC 6V–24V.

**Arduino Example Code**

This code uses the **ModbusMaster library** to read temperatures from the first 7 channels.

<code c>
#include <ModbusMaster.h>
#include <SoftwareSerial.h>

#define MAX485_RE_DE 4
SoftwareSerial rs485(2, 3); // RX, TX

ModbusMaster node;

void preTransmission() { digitalWrite(MAX485_RE_DE, 1); }
void postTransmission() { digitalWrite(MAX485_RE_DE, 0); }

void setup() {
  pinMode(MAX485_RE_DE, OUTPUT);
  digitalWrite(MAX485_RE_DE, 0);

  Serial.begin(9600);
  rs485.begin(9600); // Default NT18B07 baud rate

  node.begin(1, rs485); // Default Slave ID is 1
  node.preTransmission(preTransmission);
  node.postTransmission(postTransmission);
}

void loop() {
  // Read 7 registers starting at 0x0000 (Channels 1-7)
  uint8_t result = node.readHoldingRegisters(0x0000, 7);

  if (result == node.ku8MBSuccess) {
    for (int i = 0; i < 7; i++) {
      int16_t rawTemp = node.getResponseBuffer(i);
      // Temperature is stored as raw value x 10. Handle negative values.
      float celsius = (rawTemp > 32767) ? (rawTemp - 65536) / 10.0 : rawTemp / 10.0;
      Serial.print("CH"); Serial.print(i+1);
      Serial.print(": "); Serial.print(celsius); Serial.println(" C");
    }
  } else {
    Serial.print("Modbus Error: 0x"); Serial.println(result, HEX);
  }
  delay(2000);
}
</code>

===== Modbus topics on lamaPLC =====
{{topic>Modbus}}

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