Interface Hardware

Relay Card

Relay card
  • I/O channels: 8 n/o relay contacts
  • Indicator LEDs
  • I2C bus channels used: 8 digital (of a possible 128*)
  • Output rating: 6A @ 240V ac
  • Size 92 x 97mm
  • Power supply: 10-28V dc, 120mA nom

 relay card datasheet

Product code: 5620

Digital Output Card

Digital output card
  • I/O channels: 8 opto-isolated MOSFETs, n-channel, open drain
  • Indicator LEDs
  • I2C bus channels used: 8 digital (of a possible 128*)
  • On resistance: 0.05 ohm
  • Output rating: 4A @ 30V dc
  • Size 87 x 97mm

[This card requires the VM2 I2C Bus to run at 5V]

 digital output datasheet

Product code: 5621

Digital Input Card

Digital input card
  • I/O channels: 16 opto-isolated inputs, 2 banks of 8
  • ‘NPN’ or ‘PNP’ polarity
  • Indicator LEDs
  • I2C bus channels used: 16 digital (of a possible 128*)
  • Input voltage: 24V dc nom
  • Size 91 x 93mm

 digital input datasheet

Product code: 5622

18/12-bit Analogue I/O Port

Analogue I/O Port
  • 1 channel up to 18-bit differential input
  • 8 channels 12-bit input
  • 2 channels 12-bit output
  • I2C bus
  • Prototyping area – uncommitted array on 2.54mm pitch

This Analogue I/O Port allows the VM2 controller to read 8 analogue inputs and generate 2 analogue outputs at 12 bit resolution, and also to read one analogue input at up to 18 bits.

Up to 2 of these Analogue I/O Ports may be connected to each I2C Bus, though in this case the 18-bit inputs are not easily usable.

The Analogue I/O Port will plug directly into the I2C connector on the Application Boards.

The kit includes an I2C cable and additional connectors.


Code snippets

Product code: 5624

Digital I/O Port

Digital I/O Port

The Digital I/O Port allows the VM2 controller to generate and detect 16 digital signals at logic levels. Up to 4 of these Digital I/O Ports may be connected to each I2C Bus. With alternative driver chips this can be increased to 8 Ports, a total of 128 digital I/O channels per I2C Bus.

The Digital I/O Port plugs directly into the I2C connector on the Application Boards.

The kit includes an I2C cable.


Product code: 1022

RS-232 Level Shifter

RS232 Level shifter

Converts between logic-level serial interfaces and industry standard RS-232 levels on a standard 9 pin D-type connector (plug). It may be useful for

  • Developing designs where an RS232 serial port is needed for development but not in the final product.
  • Adding more RS232 ports to a standard VM2 Application Board.


Product code: 5914

Extending VM2

Digital output card

The VM2 controller can connect to a host of different devices, and many useful interfaces are built into the standard VM2 Application Boards. This page shows a range of interfaces that can extend the capabilities of the application boards.

These circuits may also be designed into a custom application board.

Interface types

Interfaces fall in three main classes

Industrial I/O Cards

The Industrial I/O cards provide an interface between the controller and industrial signal levels. Up to 8 cards may be directly connected to a single VM2 system, and another 8 if a second I2C Bus is implemented.  The cards plug directly into the I2C connector on any standard Application Board.

  • I2C cable supplied
  • Fully integrated with Venom language
  • Pluggable screw terminals – ‘Combicon’
  • Industry standard signal levels
  • Up to 16 cards can be connected
  • LED level indicators
  • Isolated input and outputs
  • Optional Long Distance I2C Interface (I2C Bus voltage must be set to 5V)

Board-level interfaces

The digital and analogue interfaces described below have I/O at logic and low power signal levels, and are intended for prototyping new applications, low volume production and use inside an instrument case.

There is also an RS-232 converter to interface between the VM2’s logic level serial interfaces and RS-232 signalling levels.

*Up to 128 Digital I/O

You can connect digital I/O cards up to a total of 64 digital inputs or outputs on the main I2C Bus.  If you implement a second I2C Bus you can add another 64 digital I/O.