APC UPS control system - Manual (Page 152)

(Shield)--------------------------(4)Chassis GND
Cable 940-0127B
USB(Computer) RJ45-10(UPS)
_________ ____________
| = = = = | [ oooooooooo ]
|_________| [____________]
(1) (4) (10) [_] (1)
+5V(1)-----------(1)+5V
DATA+(2)-----------(9)DATA+
DATA-(3)-----------(10)DATA-
GND(4)-----------(7)Signal GND
(Shield)-----------(4)Chassis GRND
Win32 Implementation Restrictions for Simple UPSes
Due to inadequacies in the Win32 API, it is not possible to set/clear/get all
the serial port line signals. apcupsd can detect: CTS, DSR, RNG, and CD.
It can set and clear: RTS and DTR.
This imposes a few minor restrictions on the functionality of some of the
cables. In particular, LineDown on the Custom Simple cable, and Low
Battery on the 0023A cable are not implemented.
Internal Apcupsd Actions for Simple Cables
This section describes how apcupsd 3.8.5 (March 2002)
treats the serial port line signals for simple cables.
apcaction.c:
condition = power failure detected
cable = CUSTOM_SIMPLE
action = ioctl(TIOCMBIS, DTR)
set DTR (enable power bit?)
apcaction.c:
condition = power back
cable = CUSTOM_SIMPLE
action = ioctl(TIOCMBIC, DTR)
clear DTR (clear power bit)
action = ioctl(TIOCMBIC, ST) clear ST (TxD)
apcserial.c:
151