APC Back-UPS Pro BP420SC pinouts
APC BackUPS Pro cable pinout
APC Smart UPS DB9 cable pinout
APC by Schneider Electric, formerly known as American Power Conversion Corporation, is a manufacturer of uninterruptible power supplies, electronics peripherals and data center products.
APC was founded in 1981. APC main focus is power protection devices. They introduced its first UPS in 1984.