---------------------------------------------------------------------------- The "trust-energy" cable defined in genpowerd.h corresponds to the cable that is described in the UPS HOWTO. I have appended the data that enabled me to build that cable and enter this new definition. Note that I don't actually use a Trust Energy Protector UPS. However the documentation that comes with my UPS happens to define the pin signals precisely as described in the 8.3.1.1 section. Call me lucky! I hope this will prove useful for other people, but please, note that I do not bear any responsibility for any potential damage the cable or the "trust-energy" configuration could cause you. It comes on a "use-at-your- own-risks" basis, but if you're a Linux user, you should already be familiar with that concept. ;-) Enjoy anyway! Raphael Manfredi October 6th, 1999 Grenoble, France ---------------------------------------------------------------------------- >>>>>>> From the UPS HOWTO on my Debian 2.1 system -- RAM <<<<<<<< 8.3.1. The computer to UPS connection The Trust Energy Protector 400/650 is equipped with a remote signal port. Using a properly designed cable, it is possible to connect the UPS port to the serial port of a computer, thus making it aware of power failure events. 8.3.1.1. The UPS signal port These are the pin assignments for the DB-9 signal port of the Trust Energy Protector 400/650, as described in the user's manual: pin 2 The relay will close when input power fails. pin 4 Common for pins 2 and 5. pin 5 The relay will close when the battery inside the Trust Energy Protector 400/650 has less than 1.5 minutes of backup time left. pin 6 The user may send a high level signal (+5V - +12V) for over 1ms to turn off the Trust Energy Protector 400/650. However this option can only be activated when the input power fails. pin 7 Common for pin 6. 8.3.1.2. The Cable This is the cable I used to connect the UPS to the serial port of my computer: computer side (DB-25) UPS side (DB-9) =================================================== 6 DSR --+ [R] = 10 kilo-Ohm resistor | 20 DTR --+----+ | | [R] [R] +--- 7 | | | 8 DCD --+----|----------- ---------|--- 2 | | 7 GND -------|----------- ---------+--- 4 | .... 5 CTS -------+----------- ------------- 5 2 TX ------------------- ------------- 6 =================================================== In the case of a DB-9 serial port, the pins 6,20,8,7,5,2 are mapped to pins 6,4,1,5,8,3. 8.3.1.3. How the cable works The computer raises DTR and checks whether DSR is high, to ensure that the cable is connected to the computer. While the power is good, DCD and CTS are both high (because of the pull-up resistors). When the power fails, the relay between pins 2 and 4 of the UPS port closes, and DCD becomes low, signalling the failure condition. Similarly, when the UPS batteries are getting low, the relay between pins 5 and 4 closes, thus lowering CTS. During a power failure the computer is able to turn off the UPS by raising TX for over 1ms. This can be easily accomplished sending a 0xFF byte to the serial port, at a low baud rate.