VT440 / Dry contacts unit

Documentation page: https://vutlan.atlassian.net/wiki/spaces/DEN/pages/35127335/VT440+Dry+contacts+unit

Product page VT440: https://vutlan.com/can-sensors/24-vt440-dry-contacts-unit.html

Product page VT32: https://vutlan.com/contacts/9-vt32-dry-contacts-board.html

Order options

VT440 can be ordered in two options:

a) VT440 (x32 dry contact inputs)

b) VT440 + VT32 (x64 dry contact inputs)

Function and purpose

Allows increasing the number of dry contact inputs connected to any Vutlan monitoring unit. Adds 32 dry contacts. Can be connected to any CAN port on a CAN bus chain. Can be chained with other CAN sensors.

The number of dry contacts inside VT440 can be increased up to 64 with an extension module "VT32 / dry contacts module".

Physical description

1. "1...32" - Dry contacts terminal.

2. "33...64" - Dry contacts empty slot. VT32 / Dry contacts board is ordered separately.

3.  "S/N" - serial number. You will need this serial number if you want to contact our support team. You mustn't lose it!

4. LEDs: "RUN" - indicates appliance connection status to the main module, "ERR" - indicates appliance lost connection to the main module.

5. "CAN 1", "CAN 2" - two equivalent digital connectors RJ12 for the connection to the master module, CAN sensors, or CAN extensions on a CAN bus, with auto-sensing.

6. "TR"  - is the nearest switch to CAN inputs. This switch should be turned "ON" on the last sensor in the CAN chain. The last sensor in the long chain with a length of more than 10 meters, the terminator should be in "OFF" position.

Do not use the DIP switch "FR" labeled "1", it should always be OFF. If this switch is turned ON, the module will turn off. This switch is only needed for programming purposes

Technical specifications

TypeCAN sensor
Network interfaceCAN open
UsageAdds x32 dry contact inputs (digital inputs)
Product dimensions(Width, Height, Depth) 215 x 40 x 40 mm
Power Consumption1 Watt
Operating temperature

Optimal temperature range:  -10° C to +80° C

Extended temperature range:  -40° С to +100° C

Mounting possibilities

19" rack-mountable


Wall mount

Max. distance from the unit225 m
Input terminals

Dry contacts / Digital inputs: 32 contacts

RJ-12 ports: x2

Expansions (ordered separately)"VT32 / Dry contacts board" - adds additional x32 contacts
Status IndicatorsRed / Green Led
Operating humidity0 to 95 %
Storage temperature-40° С to +100° C
Storage humidity0 to 95 %
Manufactured in (country)Manufactured in Slovak Republic, E.U.
HS Code8471 50 000
Daisy chainYes, possible

Package includes

Make sure that the contents of the delivery meet the following configuration. Report a missing or damaged component to your supplier. If damage occurred during transportation, contact the appropriate delivery service.

Package contentDescription
Dry contacts unit VT440.
RJ11 6P4C 2m CAN cable
Terminal 6*3.5 mm - 8 pcs 
Screws M3*8 - 6 pcs
19" rack brackets - 2 pcs.
6Self-adhesive rubber foot - 4 pcs



"TR"  - is the nearest switch to CAN inputs. This switch should be turned "ON" on the last sensor in the CAN chain. The last sensor in the long chain with a length of more than 10 meters, the terminator should be in "OFF" position.

pic.2.1: TR is ON, FR is OFF.                    pic.2.2: TR is OFF, FR is OFF.

CAN devices connection

This section includes child pages:

CAN sensors and CAN units connection

  1. Connect CAN devices to any port CAN1 or CAN2 on the monitoring system using a cable supplied. CAN sensors can also be connected to the port of another CAN sensor or CAN unit which is connected to the CAN bus. Determination of the devices and their connection is done through a web interface.

    You can connect up to a maximum of x12 CAN sensors and CAN devices together on one CAN bus (approximately)!

    If you want to connect more than x12 CAN units, you need to use CAN-12V-1A / CAN Power Supply

  2. The TR should be "ON" for the last sensor on each bus "CAN 1" and "CAN 2". See section "TR" below.

This procedure applies to the following sensors, which are supported by the appliance and are connected to the CAN ports:

CAN sensors, modules:

CAN extensions:

Read more about Setting up CAN sensors.

Used cable and limit line length

The maximum length of the CAN line in Vutlan monitoring systems is 225 m due to limitations on the ohmic resistance of cables with RJ12 connectors.

It is advisable to use two or three pairs of cables such as UTP Cat3.5.6 with 24AWG with a copper core. It is possible to use a 4-wire or 6-wire TRONIC or UTP CCA cable, but the maximum CAN line length will be reduced.

TR termination switch

The last sensor TR switch on a CAN chain must always be terminated, ( switched ON ). Sensors on a CAN bus that is in the middle should have TR switched OFF.

FR should always be OFF.

TR switch is always the DP switch nearest to the CAN bus.

Only older Vutlan models have an FR switch.

pic.1.1: FR is OFF, TR is ON.                    pic.1.2: FR is OFF, TR is OFF.

Adding CAN modules and sensors

To connect the CAN module or CAN sensor to the CAN bus of the system, go to the interface >> CAN configuration panel >> Select the CAN1 or CAN2 tab (select the connected physical CAN1 or CAN2 port on the master module).

Click the "Configure" button and wait. The system will start CAN bus polling, soon it will display the data lines and write “Done!”. The modules and sensors connected to the CAN input will appear in a tab in the list. Click the Apply button and then Restart.

The green LED "CAN status" of the device will light up.

Go to panel "System Tree" to see the new devices or new sensors. The article numbers for CAN devices are VT4xx. If they do not appear, wait, or refresh.

If after clicking the "Configure" button the poll is reset to the phrase "Update", then the line is not connected or the terminators on the bus are not agreed. It is necessary to check and change the condition of the TR terminators (See "TR termination switch" section above) on the modules or check and possibly change the connection cables.

Warning: If the bus is not matched, that is, there are bad contacts or bad cables, or the TR terminator is in the"ON" position on the intermediate devices (position 2 on the VT408), or the line is too short for matching on both CAN end devices, CAN on this line can work malfunctioning, or the line as a whole may not function. (CAN line failure may occur if the parallel CR switch is in state 1, must be in OFF).


CAN sensors have LEDs that indicate the following states:

  • Red continuous light, green flickers - no communication with the master module

  • Red continuous light, green is off - there is a connection with the master unit, but is not included in the monitoring system (not configured)

  • Red is off, Green continuously light - work as part of a monitoring system

  • All LEDs are off: no power or sensor is defective.

Maximum cable length test

VT408Sensor extension unit



VT430Rack control unit

VT440Dry contacts unit

VT460Smoke, humidity, temperature

VT490 / VT490i

Dual humidity and temperature sensor /

Pressure, humidity & temperature sensor


see also:

Setting up CAN

Enable CAN

Inside the web interface of the system go to >> Preferences menu >> Network tab >> Enable CAN >> Save >> Save settings to flash (An icon in the top right corner of the web interface)


CAN bus is used for connection of CAN sensors and CAN modules. The device has two independent CAN nodes: CAN1 and СAN2.

Before using CAN sensor module, CAN bus must be configured to operate with this CAN sensor module. To configure CAN bus go to "Main menu" >> "CAN" menu, which in turn has two identical tabs - one for each node.

Each station tab contains current information on the status of the node and a list of  CAN sensor modules connected to this node. 

The following operations can be carried out on the CAN bus node:

  • Refresh - updates the current information on the status of the node;
  • Configure -  launches configuration process of the nodes for CAN sensor modules connected to it, the old configuration is lost
  • Save - saves the list of CAN sensor modules in flash memory;
  • Restart - restarts the CAN bus node.

To delete a CAN sensor module, click on the desired module. A modal window will pop up. Press "Delete" and confirm.

To set up a CAN bus node for operation with the CAN sensor module, connect CAN module to CAN network and run corresponding configuration procedure in the web interface using the command "Configure". The configuration process is displayed at the bottom of the tab and lasts approx. 2 minutes.  Detected modules will be added to the list of modules during the configuration process. After completing configuration the node returns to its normal operation. Sensors of detected CAN modules are added to the tree of elements. 

The names of the sensors are automatically set in the form {module name}{serial number}-{type of sensor} and can be edited.

If you need to remove CAN sensor module from the configuration list use command Delete, then use command "Save" to apply the changes you made and restart the node using the command Restart.  


Vutlan s.r.o. (LLC)

Remote Infrastructure Monitoring and Control

43 ul.Svornosti, 821 06 Bratislava,

Slovak Republic