User's Manual UPS control system

Connecting a APC USB UPS to either a PC USB
or Serial Port
An interesting fact is that the USB ports (actually an RJ45 connector)
on APC UPSes not only speak USB, but also serial apcsmart and dumb
voltage-signalling as well! This is something that one of our users discovered
by accident. With the Custom RJ45 cable (actually a RJ45 to serial cable)
described below plugged into the APC UPS USB socket at one end and the
other end plugged into a serial port on your PC, any APC USB UPS (except
some of the newer really low cost models) will act as a serial-line device.
Cables
You can either use the cable that came with your UPS (the easiest if we
support it) or you can make your own cable. We recommend that you
obtain a supported cable directly from APC.
If you already have an APC cable, you can determine what kind it is by
examining the flat sides of the two connectors where you will find the cable
number embossed into the plastic. It is generally on one side of the male
connector.
To make your own cable you must first know whether you have a UPS that
speaks the apcsmart protocol or a “dumb” UPS that uses serial port line
voltage signalling.
If you have an apcmart UPS, and you build your own cable, build a Smart-
Custom cable. If you have a voltage-Signalling or dumb UPS, build a Simple-
Custom cable. If you have a BackUPS CS with a RJ45 connector, you can
build your own Custom-RJ45 cable.
Smart-Custom Cable for SmartUPSes
SMART-CUSTOM CABLE
Signal Computer UPS
DB9F DB9M
RxD 2 -------------------- 2 TxD Send
TxD 3 -------------------- 1 RxD Receive
GND 5 -------------------- 9 Ground
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