Does the Opto-4 need external power?
No, it takes power from the RS232 handshaking lines. Please note that this requires the RS232 port to have these handshaking lines both connected and enabled. Most full RS232 ports (provided through DB9 connectors) on PC’s will comply with this. If there are no handshaking lines on the RS232 port then see the instructions on how to connect external power in the Quick Start Guide on the OPTO-4 downloads page.