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The OPT-821A daughter board provides optical isolation and signal conditioning of the DAQ cards input digital ports.

The board provides eight input blocks (isolated between each other) for processing DC signals up to 32V. All channels work as inverting, i.e. high input voltage is represented by the output level "L".

The control port operates in NPN open collector mode (requires pull up resistors; meets all DAQ cards TEDIA) or TTL/HC mode (requires an external power supply).

Every channel is fitted with an indicating LED, signalizing high input signal level.

OPT-821A board is supplied as an unencapsulated kit, a plastic housing DIN-801 suitable for mounting on the 35 mm DIN rail is supplied optionally.

Delivery details

The product packet includes the board only (cables and DIN35 housing are not included), documentation is available in the Download section.


Type OPT-821A
Number of digital inputs 8
Digital inputs signal level 0÷5VDC (low-level)
15÷32VDC (high-level)
Input impedance approx. 6kΩ
Overvoltage protection ±50VDC continuously
Delay (low->high, high->low) <0.5ms
Isolation voltage 1.5kVRMS (inputs against DAQ card)
100VDC (between inputs)
Control port signals NPN open collector or TTL/HC compatible
Power supply 8÷30VDC, 15mA max.
(only required for TTL/HC mode)
Dimensions approx. 72x88 mm
Weight approx. 70 g
Weight and dimensions
of product packaging
approx. 120 g
cardboard box approx. 180x130x40 mm