In preparation for possible bad weather & power outages, I was trying to get an UPS unit to communicate with my (Debian) Linux server through its serial port and I was running into problems. I actually figured out the problem halfway through writing this e-mail (when I got to the cable part), but I thought I'd still send this in, for future reference.
I first enabled the Serial Port in the BIOS and left the Memory & IRQ settings to their default values. Then in the 'dmesg' output, I see this line:
# grep tty /var/log/kern.log Sep 15 11:43:03 ruby kernel: ttyS00 at 0x03f8 (irq = 4) is a 16550A
Why is there two 0's at the end there? I don't see a /dev/ttyS00 (I do see a /dev/ttyS0:
# ls -l /dev/ttyS* crw-rw---- 1 root dialout 4, 64 Mar 14 2002 /dev/ttyS0 crw-rw---- 1 root dialout 4, 65 Mar 14 2002 /dev/ttyS1 crw-rw---- 1 root dialout 4, 66 Mar 14 2002 /dev/ttyS2 crw-rw---- 1 root dialout 4, 67 Mar 14 2002 /dev/ttyS3
So now I'm feeling good - it looks like the serial port is working on the Linux server, so I hook it up and the UPS vendor (CyberPower) refers to me powstatd:
http://dollar.biz.uiowa.edu/powstatd/
So I get that installed and it has a dandy powstatd.conf file that I've told it to watch all of those ttyS# options, all with the same result:
# powstatd -t powstatd: online (standalone), watching /dev/ttyS0. CTS DSR DCD RNG DTR RTS STATUS 0 0 0 0 0 1 LOW 0 0 0 0 0 1 LOW
I should see some 1's in there in the CTS, DSR, DCD or the RNG columns, especially when I unplug the UPS, but nothing. So I figure something's up w/ the serial port on the UPS and/or the serial cable, but I've tried switching to different UPS'es. So then I try a different cable (one that came w/ the unit {I was trying a different/longer one}) and voila! It works!
# powstatd -t powstatd: online (standalone), watching /dev/ttyS0. CTS DSR DCD RNG DTR RTS STATUS 1 0 1 0 0 1 OK 1 0 1 0 0 1 OK
So I'm off to finish up the configuration! I hope someone finds this useful, too, though I'm sure you would probably initially attempt to use the actual cable that came w/ the vendor. ;)
Cheers,
Jason
PS: Thanks Jon & Ben for helping me w/ my network routing ... I was able to fix the problem by doing a "route -del" on the eth1 card for 0.0.0.0.
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