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Re: [K12OSN] Uninteruptable Power Supply UPS with Linux



On 10/16/06, Robert Arkiletian <robark gmail com> wrote:


 Why do you recommend usb over serial?

The cheaper APCs don't do true serial communication (i.e., sending
data to the computer). Instead, they set certain signals (like CTS,
IIRC) to indicate their condition.

USB allows for real communication with the host computer, and I
_believe_ that means real data gets sent to that host. For example,
here's the output of "apcaccess" on my workstation:

APC      : 001,034,0890
DATE     : Mon Oct 16 12:59:50 MDT 2006
HOSTNAME : source-server.prosocial.local
RELEASE  : 3.12.4
VERSION  : 3.12.4 (19 August 2006) redhat
UPSNAME  : source-server.prosocial.local
CABLE    : USB Cable
MODEL    : Back-UPS NS 600
UPSMODE  : Stand Alone
STARTTIME: Fri Oct 13 13:05:46 MDT 2006
STATUS   : ONLINE
LINEV    : 118.0 Volts
LOADPCT  :   0.0 Percent Load Capacity
BCHARGE  : 100.0 Percent
TIMELEFT :  42.8 Minutes
MBATTCHG : 5 Percent
MINTIMEL : 3 Minutes
MAXTIME  : 0 Seconds
LOTRANS  : 088.0 Volts
HITRANS  : 139.0 Volts
ALARMDEL : Always
BATTV    : 13.5 Volts
LASTXFER : Low line voltage
NUMXFERS : 0
TONBATT  : 0 seconds
CUMONBATT: 0 seconds
XOFFBATT : N/A
STATFLAG : 0x07000008 Status Flag
MANDATE  : 2005-12-26
SERIALNO : 3B0601X00177
BATTDATE : 2000-00-00
NOMBATTV :  12.0
FIRMWARE : 18.w1 .D USB FW:w1
APCMODEL : Back-UPS NS 600
END APC  : Mon Oct 16 12:59:51 MDT 2006


I'm reasonably certain a serial signal-only connection can't convey
that much information to the host (I've no great emotional stake in
this, and won't complain if somebody can post similar output from a
signal-only UPS).


 I am using the CentOS 4 based k12ltsp.

RPMs are available for RHEL3 at the apcupsd site
(http://sourceforge.net/project/showfiles.php?group_id=54413&package_id=73150).
I think that's the closest match to CentOS 4 (being directly descended
from RHEL4).

Calvin


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