It is set of input/output registers. You can read a detail description of device in pdf-file. The device is intended for digital input/output in control systems of physical installations. The device includes two output ports (registers) and four input ports (registers). All ports (registers) have 8 bits size.

Ports of CURVV are:
- output register (8 bits) with optical isolation (up to 10 mA, 50 V);
- input register (8 bits) with optical isolation (2,5-6 V);
- output register without optical isolation (up to 300 mA, 15 V):
- three registers (3*8 bits) with TTL inputs (0-6 V);
- all inputs and outpus are protected against overvoltage and incorrect polarity.