On Feb 26, 2012, at 3:14 PM, Steve Read wrote:
> I made a simple device to apply either +12 or -12volts to both pin 1(DCD) and
> pin 8 (CTS) to help me understand the correct handshake but I am very
> confused.
>
> Here is a table of what I get:
>
> State Pin 1 Pin 9 Note What I understand it means
> 1 +12V +12V OL On Line - normal
> operation.
> 2 -12V +12V LB OL I don't understand this. It
> should be On Battery.
> 3 +12V -12V OB I thought this should
> be Low Battery.
> 4 -12V -12V OL I thought the server
> should shut down?
>
> Note: results of running:
> /usr/local/ups/bin/upsc sdrups@localhost ups.status
For reference, here is the block for type=9 in genericups.h:
/* Type 9 */
{ "APC",
"Back-UPS",
"APC Back-UPS (940-0023A cable)",
0, /* cable power: none */
TIOCM_CD, 0, /* online: CD off */
TIOCM_CTS, TIOCM_CTS, /* low battery: CTS on */
TIOCM_RTS /* shutdown: RTS */
},
And the text from the genericups man page:
- - - - - - - - - -
9 = APC Back-UPS/Back-UPS Pro/Smart-UPS with 940-0023A cable
[CP=none] [OL=-DCD] [LB=CTS] [SD=RTS]
- - - - - - - - - -
For your tests where you apply voltage directly, CP is not relevant. (I assume
your microcontroller provides its own power to the serial port control lines.)
Also, SD=RTS is the shutdown signal *to* the UPS (saying that NUT acknowledges
the UPS' low battery condition). But you mentioned pins 1 (DCD) and 8 (CTS), so
we can ignore that for now.
The way I read this, online with a good battery should be negative voltages on
both DCD and CTS. OB+LB should be positive voltages on both. On Battery (but
not yet low) should be DCD high, CTS low. (The fourth condition could occur if
the power has returned, but the battery has not yet charged.)
I am confused as to how you could get OL for both +/+ and -/- states. Your
table says Pin 1 and Pin 9, but earlier you mention Pin 1 and Pin 8. Could pin
8 have been floating during the voltage test?
You can use statserial to double-check that your serial port hardware is still
good.
--
Charles Lepple
clepple@gmail
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