Srial port relay is through the computer serial port /USB to send the command to switch 4 relay, and can read the four way switch quantity input signal.
Power input range: DC9-24V. Positive and negative reverse protection.
Relay output capacity: AC 220V/10A max; DC 30V/10A max.
Relay switch input by optocoupler isolation, input switch quantity signal 5-24V. High and low level can be set.