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Digital Input Expansion Card

Supplier: Sphere Systems

The digital inputs have 8-on voltage-free contact closure inputs.

Price Guide: POA

Digital Input

The digital inputs have 8-on voltage-free contact closure inputs. The inputs are ground-referenced and have an open-circuit voltage of 8 to 12 Volts DC.

The inputs are optically isolated from the expansion card electronics to minimise possible damage from field fault conditions.

A LED is added to provide visual indication of pulse detection monitors each input.

Input debouncing can be configured through software commands to provide noise immunity on mechanically switched inputs.

Inputs debouncing reduce the input pulse detection rate by a factor of three.


  • The card is designed to fit Augat 3TK Series Snap Track.
  • The Digital Input Expansion Card is 91 mm long by 82.5 mm wide and 18 mm high without connectors.

Power supply

Connection to the IO Expansion BUS is through a 20-way flat cable that also supplies power to the expansion board

External Connection

The field wiring is connected to the card via a Phoenix Contact 12 way, screw terminated, cable mounted plug.


  • All electronics and power supplies can be mounted in plastic or metal sealed enclosures to meet environmental requirements.
  • No fans, heat sinks or other heat dissipation methods are required. Field wiring connections can be provided through plugs, sockets or penetrations in the enclosure meeting expected environmental requirements.
  • Enclosures will be sized to accommodate the equipment to be housed.

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