CAN devices connection

1 CAN sensors and CAN units connection
2 CAN cable and limited line length
3 TR termination switch
4 Adding CAN modules and sensors
5 Maximum cable length test
6 Additional power for long-chain
7 x2 CAN port systems
8 Additional reading

CAN sensors and CAN units connection

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 that is connected to the CAN bus. Determination of the devices and their connection is done through a web interface.

You can connect up to x32 CAN units in a CAN bus chain.

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, and modules:

CAN extensions:

CAN cable and limited 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.

Vutlan AWG24 cables have low resistance.

Since the conductivity of aluminum is much lower than that of copper, the resistance of CCA cables is much higher than that of pure copper cables of the same size.

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 the 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).

LEDs

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

Model	Description	50m	100m	150m	200m

Model	Description	100m	150m
VT408	Sensor extension unit	ok
VT408DIN		ok
VT430	Rack control unit	ok
VT440	Dry contacts unit	ok	long-chain
VT460	Smoke, humidity, temperature	ok
VT490 / VT490i	Dual humidity and temperature sensor / Pressure, humidity & temperature sensor	ok

Additional power for long-chain

When connecting a very long chain, you need to use the CAN-12V-1A / CAN Power Supply module for additional power for CAN units/extensions/sensors every 8-12 sensors.

x2 CAN port systems

Some Vutlan main monitoring systems have x2 CAN ports. That means they can support two individual CAN chains. Each chain has to be configured individually. E.g. “VT855t / Data center monitoring unit” has x2 CAN ports.