Connection of 1-wire sensors with converter to ModBus

Measuring temperature 29.02.2020 11:32 29.02.2020 11:32

A module on the CIB bus C-1W-4000M now available for connecting 1-wire sensors.

 

For easy integration of single-purpose circuits from Dallas communicating via 1-Wire bus, the TUDS-40 MOD unit supplied by Firvena is designed, which independently processes communication from DALLAS sensors on its two 1-Wire data lines and further transmits information to Foxtrot system via standard communication interface. RS-485 with MODBUS RTU protocol. There is a library for the Mosaic environment, which allows easy installation and operation of connected sensors. Detailed information on using the unit, its configuration, support for the Foxtrot system and information on peripherals can be found at www.modbusto1wire.cz.

 

It can operate up to 20 sensors (40 in total) on each of the 1-Wire lines.

For simple and easy reading / deleting of individual addresses of temperature sensors, the unit is equipped with a two-digit LED display and control buttons. Sensor programming can also be used on a PC with an RS-485 converter.

Signaling LEDs on the front panel indicate the power supply of the device and the presence of a temperature sensor for each line separately.

 

1-Wire bus is easy to install. We recommend using a Cat 5e, Cat 6 or Cat 7 type twisted shielded (FTP) cable to route the cabling. It is advisable to use terminal boards that contain line balancing circuits (the line is resistant to line interference) and a disconnecting jumper for easy connection. programming of sensors into the converter.

 

For reliable operation of the TUDS-40-MOD device, we recommend using the manufacturer's proven temperature sensors, which contain a connectable terminal block with electrical circuits, ensuring protection and balance of the line. The DALLAS temperature sensor has its code set by the manufacturer, on the basis of which it communicates with the TUDS-40-MOD unit.

 

Basic parameters of the TUDS-40 MOD module

Power voltage 24 VAC/DC  ±10 % 
own equipment collection 2 W 
indication  yes, LED display
System interface RS-485
protocol MODBUS RTU, slave, supported functions 03
communication speed optional 9,6 kBd, 19,2 kBd, 38,4 kBd, 76,8 kBd 
address 0 ÷ 247 
parity no
stopbit 2 (the device also responds to one stop bit) 
galvanic isolation from power supply yes
iCommunication to sensors typ 1-Wire (DALLAS) 
number of temperature sensors on one bus 20 
number of buses (lines) 2 
galvanic isolation from power supply yes
indication of the status of buses (lines) yes, LED 




Fig. 1 Basic example of connecting the TUDS-40 MOD unit

 

Notes:

  1. Each 1wire bus (Line 1, Line 2) can have only 20 sensors connected, the connection must be a strict line without taps (there are taps in the diagram only to show the connection).
  2. The maximum length of each line is about 300 m.
  3. Recommended FTP shielded cable.
  4. The polarity of the 24 VDC supply voltage is arbitrary, the module can also be supplied from a 24 VAC source.