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<h1>Cables</h1>
First, you will need a serial port cable between the APC UPS and your computer
running <b>apcupsd</b>. You can use either the cable that came with your
UPS (the easiest if we support it) or you can make your own cable.
We recommend that you obtain a supported cable directly from APC.
<p>If you already have an APC cable, you can determine what kind it
is by examining the flat sides of the two connectors where you will
find the cable number embossed into the plastic. It is generally
on one side of the male connector.
<p>To make your own cable, first, you must know whether you have a Smart UPS
that sends ASCII characters called <b>Smart Signaling</b>,
or a "dumb" UPS that uses serial port line voltage signaling, called
<b>Simple Signaling</b>.
<p>
The "dumb" UPSes are older models such as
the BackUPS (not BackUPS Pro) and the ShareUPS Basic Port that
use <b>Simple Signaling</b>. Most other UPSes use
<b>Smart Signaling</b>. If in
doubt consult the <a href="configure.html">Configuration Section</a> of
this manual, or the documentation that came with your UPS.
<h3>Smart Signaling Cable for SmartUPSes</h3>
If you must build your own cable, and you have a
Smart UPS, we recommend building the cable as
follows:
<pre>
SMART-CUSTOM CABLE
Signal Computer UPS
DB9F DB9M
RxD 2 -------------------- 2 TxD Send
TxD 3 -------------------- 1 RxD Receive
GND 5 -------------------- 9 Ground
</pre>
When using this cable with <b>apcupsd</b> specify the
following in <b>apcupsd.conf</b>:
<pre>
UPSCABLE smart
UPSTYPE smartups
DEVICE /dev/ttyS0 (or whatever your serial port is)
</pre>
<h3>Smart Signaling Cable for BackUPS CS Models</h3>
If you have a BackUPS CS, you are probably either using
it with the USB cable that is supplied or with the
940-0128A supplied by APC, which permits running the
UPS in dumb mode. By building your own cable, you can now
run the BackUPS CS models (and perhaps also the ES models)
using Smart signaling and have all the same information that
is available as running it in USB mode.
<p>The jack in the UPS is actually a 10 pin RJ45.
However, you can just as easily use a 8 pin RJ45
connector, which is more standard (ethernet TX,
and ISDN connector).
>Below, you will find a diagram for the CUSTOM-RJ45
cable:
<pre>
CUSTOM-RJ45 CABLE
Signal Computer UPS UPS
DB9F RJ45-8 RJ45-10
RxD 2 ---------------- 1 2 TxD Send
TxD 3 ---------------- 7 8 RxD Receive
GND 5 ---------------- 6 7 Ground
The RJ45-8 pins are: looking at the end of the connector:
8 7 6 5 4 3 2 1
___________________
| . . . . . . . . |
| |
-------------------
|____|
The RJ45-10 pins are: looking at the end of the connector:
10 9 8 7 6 5 4 3 2 1
_______________________
| . . . . . . . . . . |
| |
-----------------------
|____|
</pre>
When using this cable with <b>apcupsd</b> specify the
following in <b>apcupsd.conf</b>:
<pre>
UPSCABLE smart
UPSTYPE smartups
DEVICE /dev/ttyS0 (or whatever your serial port is)
</pre>
<p>
The information for constructing this cable was discovered
and transmitted to us by slither_man. Many thanks!
<h3>Simple Signaling Cable for "dumb" UPSes</h3>
<b>NOTE. YOU DO NOT HAVE THIS CABLE UNLESS YOU BUILT IT
YOURSELF. THE SIMPLE-CUSTOM CABLE IS NOT AN APC PRODUCT.</b>
<p>
For "dumb" UPSes using Simple Signaling, if you
are going to build your own cable, we recommend to make
the cable designed by the <b>Apcupsd</b> team
as follows:
<pre>
SIMPLE-CUSTOM CABLE
Signal Computer UPS
DB9F 4.7K ohm DB9M
DTR 4 --[####]--* DTR set to +5V by Apcupsd
|
CTS 8 ----------*--------- 5 Low Battery
GND 5 -------------------- 4 Ground
DCD 1 -------------------- 2 On Battery
RTS 7 -------------------- 1 Kill UPS Power
</pre>
List of components one needs to make the Simple cable:
<ol>
<li>One (1) male DB9 connector, use solder type connector only.
<li>One (1) female DB9/25F connector, use solder type connector only.
<li>One (1) 4.7K ohm 1/4 watt 5% resistor.
<li>resin core solder.
<li>three (3) to five (5) feet of 22AWG multi-stranded four or more
conductor cable.
</ol>
<p>
- Solder the resistor into pin 4 of the female DB9 connector.
<p>
- Next bend the resistor so that it connects to pin 8 of the female DB9 connector.
<p>
- Pin 8 on the female connector is also wired to pin 5 on the male DB9 connector. Solder both
ends.
<p></p>
- Solder the other pins, pin 5 on the female DB9 to pin 4 on the male
connector; pin 1 on the female connector to pin 2 on the male connector; and
pin 7 on the female connector to pin 1 on the male connector.
<p></p>- Double check your work.
<br>
<p>We use the DTR (pin 4 on the female connector) as our +5 volts power for the circuit.
It is used as the Vcc pull-up voltage for testing the outputs on
any "UPS by APC" in Simple Signaling mode. This cable may not work on a
BackUPS Pro if the default communications are Smart Signaling mode. This
cable is also valid for "ShareUPS" BASIC Port mode and is also
reported to work on SmartUPSes. However, the Smart Cable described above is much
simpler.
To have a better idea of what is going on inside <b>apcupsd</b>, for the SIMPLE
cable <b>apcupsd</b> reads three signals and sets three:
<pre>
Reads:
CD, which apcupsd uses for the On Battery signal when high.
CTS, which apcupsd uses for the Battery Low signal when high.
RxD (SR), which apcupsd uses for the Line Down
signal when high. This signal isn't used for much.
Sets:
DTR, which apcupsd sets when it detects a power failure (generally
5 to 10 seconds after the CD signal goes high). It
clears this signal if the CD signal subsequently goes low
-- i.e. power is restored.
TxD (ST), which apcupsd clears when it detects that the CD signal
has gone low after having gone high - i.e. power is restored.
RTS, which apcupsd sets for the killpower signal -- to cause the UPS
to shut off the power.
</pre>
<p>Please note that these actions apply only to the SIMPLE cable, the signals
used on the other cables are different.
</p>
Finally, here is another way of looking at the CUSTOM-SIMPLE cable:
<pre>
APCUPSD SIMPLE-CUSTOM CABLE
Computer Side | Description of Cable | UPS Side
DB9f | DB25f | | DB9m | DB25m
4 | 20 | DTR (5vcc) *below | n/c |
8 | 5 | CTS (low battery) *below | <- 5 | 7
2 | 3 | RxD (no line voltage) *below | <- 3 | 2
5 | 7 | Ground (Signal) | 4 | 20
1 | 8 | CD (on battery from UPS) | <- 2 | 3
7 | 4 | RTS (kill UPS power) | -> 1 | 8
n/c | 1 | Frame/Case Gnd (optional) | 9 | 22
Note: the <- and -> indicate the signal direction.
Optional connections of original SIMPLE-CUSTOM specification
that are not used.
4.7K ohm
DTR 4 --[####]--* Note needed
|
RxD 2 ----------*--------- 3 Not used by Apcupsd
</pre>
When using this cable with <b>apcupsd</b> specify the
following in <b>apcupsd.conf</b>:
<pre>
UPSCABLE simple
UPSTYPE backups
DEVICE /dev/ttyS0 (or whatever your serial port is)
</pre>
<h2>Other APC Cables that Apcupsd Supports</h2>
<b>Apcupsd</b> will also support the following off the shelf cables that are
supplied by APC:
<p>
940-0020B/C Simple Signal Only, all models.
<br>
940-0023A Simple Signal Only, all models.
<br>
940-0119A Simple Signal Only, Back-UPS Office, and BackUPS ES.
<br>
940-0024[B/C/G] SmartMode Only, SU and BKPro only.
<br>
940-0095[A/B/C] PnP (Plug and Play), all models.
<br>
940-1524C SmartMode Only
<br>
940-0127A/B USB Cables
<br>
940-0128A Simple Signal Only, Back-UPS CS in serial mode.
<h2><a name="CableModes"></a>Simple Signaling Features Supported by Apcupsd for Various Cables</h2>
The following table shows the features supported by the
current version of <b>Apcupsd</b> (3.8.5 or later) for various
cables running the UPS in Simple Signaling mode.
<p class="indent">
<table cellspacing="2" cellpadding="2" border="2">
<tr align="center" valign="middle"><th>Cable</th> <th>Power Loss</th> <th>Low Battery</th> <th>Kill Power</th> <th>Cable Disconnected</th></tr>
<tr align="center" valign="middle"><td>940-0020B</td> <td>Yes</td> <td>No</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0020C</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0023A</td> <td>Yes</td> <td>No</td> <td>No</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0119A</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0127A</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0128A</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>940-0095A/B/C</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
<tr align="center" valign="middle"><td>simple</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>No</td></tr>
</table>
</p>
<h2>Simple UPS Signaling</h2>
Apparently, all APC signaling UPSes have the same signals on the
output pins of the UPS. The difference at the computer end is due
to different cable configurations. Thus, by measuring the connectivity
of a cable, one can determine how to program the UPS. This
is to be verified.
<p>
The signals presented or accepted by the UPS on its DB9
connector using the numbering scheme listed above is:
<pre>
UPS Pin Signal meaning
1 <- Shutdown when set by computer for 1-5 seconds.
2 -> On battery power (this signal is normally low but
goes high when the UPS switches to batteries).
3 -> Mains down (line fail) See Note 1 below.
5 -> Low battery. See Note 1 below.
6 -> Inverse of mains down signal. See Note 2 below.
7 <- Turn on/off power (only on advanced UPSes only)
Note 1: these two lines are normally open, but close when the
appropriate signal is triggered. In fact, they are open collector
outputs which are rated for a maximum of +40VDC and 25 mA. Thus
the 4.7K ohm resistor used in the Custom Simple cable works
quite well.
Note 2: the same as note 1 except that the line is normally closed,
and opens when the line voltage fails.
</pre>
<h2>The Back-UPS Office 500 signals</h2>
The Back-UPS Office UPS has a telephone type jack as
output, which looks like the following:
<pre>
Looking at the end of the connector:
6 5 4 3 2 1
_____________
| . . . . . . |
| |
| |----------|
|__|
</pre>
<p>It appears that the signals work as follows:
<pre>
UPS Signal meaning
1 (brown) <- Shutdown when set by computer for 1-5 seconds.
2 (black) -> On battery power
3 (blue) -> Low battery
4 (red) Signal ground
5 (yellow) <- Begin signaling on other pins
6 (none) none
</pre>
<h2>940-0020B Cable Wiring</h2>
This diagram is for informational purposes and is
not complete. Although we do not know what the
black box semi-conductor contains, we believe
that we understand its operation (many thanks
to Lazar M. Fleysher for working this out).
<p>
This cable can
only be used on simple signaling UPSes, and
provides the On Battery signal as well as
kill UPS power. Most recent evidence (Lazar's
analysis) indicates
that this cable under the right conditions may
provide the Low Battery signal. This is to be
confirmed.
<pre>
APC Part# - 940-0020B
Signal Computer UPS
DB9F DB9M
CTS 8 -------------------- 2 On Battery
DTR 4 -------------------- 1 Kill power
GND 5 ---------------*---- 4 Ground
|
--- *---- 9 Common
DCD 1 ----|///|----------- 5 Low Battery
|\\\|
RTS 7 ----|///| (probably a
--- semi-conductor)
</pre>
Thanks to Lazar M. Fleysher for proper
<h2>940-0020C Cable Wiring</h2>
This diagram is for informational purposes and may
not be complete, we don't recommend that use it
to build you build one yourself. This cable can
only be used on simple signaling UPSes, and
provides the On Battery signal, the Low Battery
signal as well as kill UPS power. In <b>apcupsd</b>
versions 3.8.2 and prior, please set your
UPSCABLE to 940-0020B. In version 3.8.3 and later,
you may specify the cable as 940-0020C.
Please note that this diagram may
not be accurate.
<pre>
APC Part# - 940-0020C
Signal Computer UPS
DB9F DB9M
CTS 8 -------------------- 2 On Battery
DTR 4 -------------------- 1 Kill power
GND 5 ---------------*---- 4 Ground
|
*---- 9 Common
RTS 7 -----[ 93.5K ohm ]----- 5 Low Battery
or semi-conductor
</pre>
<h2>940-0023A Cable Wiring</h2>
This diagram is for informational purposes and may
not be complete, we don't recommend that use it
to build you build one yourself. This cable can
only be used on simple signaling UPSes, and apparently only
provides the On Battery signal. As a consequence, this
cable is pretty much useless, and we recommend
that you find a better cable because all APC UPSes
support more than just On Battery.
Please note that we are not sure the following diagram
is correct.
<pre>
APC Part# - 940-0023A
Signal Computer UPS
DB9F DB9M
DCD 1 -------------------- 2 On Battery
3.3K ohm
TxD 3 --[####]-*
|
DTR 4 ---------*
GND 5 ---------------*---- 4 Ground
|
*---- 9 Common
</pre>
<h2>940-0095A Cable Wiring</h2>
This cable is used
with the <b>backupspropnp</b> and the <b>newbackupspro</b>.
It is the definitive
wiring diagram for the 940-0095A cable submitted
by Chris Hanson <cph@zurich.ai.mit.edu>, who
disassembled the original cable, destroying it in
the process. He then built one from his diagram and it
works perfectly.
<pre>
Construction and operation of the APC #940-0095A cable.
This cable is included with the APC Back-UPS Pro PNP series.
UPS end Computer end
------- ------------
47k 47k
BATTERY-LOW (5) >----R1----*----R2----*----< DTR,DSR,CTS (4,6,8)
| |
| |
| / E
| |/
| B |
*-------| 2N3906 PNP
|
|\
\ C
|
|
*----< DCD (1) Low Batt
|
|
R 4.7k
3
|
4.7k |
SHUTDOWN (1) >----------*----R4----*----< TxD (3)
|
| 1N4148
*----K|---------< RTS (7) Shutdown
POWER-FAIL (2) >--------------------------< RxD,RI (2,9) On Batt
GROUND (4,9) >--------------------------< GND (5)
Operation:
* DTR is "cable power" and must be held at SPACE. DSR or CTS may be
used as a loopback input to determine if the cable is plugged in.
* DCD is the "battery low" signal to the computer. A SPACE on this
line means the battery is low. This is signalled by BATTERY-LOW
being pulled down (it is probably open circuit normally).
Normally, the transistor is turned off, and DCD is held at the MARK
voltage by TxD. When BATTERY-LOW is pulled down, the voltage
divider R2/R1 biases the transistor so that it is turned on, causing
DCD to be pulled up to the SPACE voltage.
* TxD must be held at MARK; this is the default state when no data is
being transmitted. This sets the default bias for both DCD and
SHUTDOWN. If this line is an open circuit, then when BATTERY-LOW is
signalled, SHUTDOWN will be automatically signalled; this would be
true if the cable were plugged in to the UPS and not the computer,
or if the computer were turned off.
* RTS is the "shutdown" signal from the computer. A SPACE on this
line tells the UPS to shut down.
* RxD and RI are both the "power-fail" signals to the computer. A
MARK on this line means the power has failed.
* SPACE is a positive voltage, typically +12V. MARK is a negative
voltage, typically -12V. Linux appears to translate SPACE to a 1
and MARK to a 0.
</pre>
<h2>940-0095B Cable Wiring</h2>
This diagram is for informational purposes and may
not be complete, we don't recommend that use it
to build you build one yourself.
<pre>
APC Part# - 940-0095B
Signal Computer UPS
DB9F DB9M
DTR 4 ----*
CTS 8 ----|
DSR 6 ----|
DCD 1 ----*
GND 5 ---------------*---- 4 Ground
|
*---- 9 Common
RI 9 ----*
|
RxD 2 ----*--------------- 2 On Battery
TxD 3 ----------[####]---- 1 Kill UPS Power
4.7K ohm
</pre>
<h2>940-0119A Cable Wiring</h2>
This diagram is for informational purposes and may
not be complete, we don't recommend that use it
to build you build one yourself. This cable is used with
the BackUPS Office UPSes.
<pre>
APC Part# - 940-0119A
UPS Computer
pins pins Signal Signal meaning
1 (brown) 4,6 DSR DTR <- Shutdown when set by computer for 1-5 seconds.
2 (black) 8,9 RI CTS -> On battery power
3 (blue) 1,2 CD RxD -> Low battery
4 (red) 5 Ground
5 (yellow) 7 RTS <- Begin signaling on other pins
6 (none) none
</pre>
<h2>BackOffice ES</h2>
The BackUPS ES has a straight through serial cable with no identification
on the plugs. To make it work with <b>apcupsd</b>, specify the
<b>UPSCABLE 940-0119A</b> and <b>UPSTYPE backups</b>.
The equivalent of cable 940-0119A is done on a PCB inside the
unit. Thanks to William Stock for supplying us with the information
about the straight through cable, the PCB, and the following diagram:
<pre>
computer ----------- BackUPS-ES -----------------
DB9-M DB-9F
pin signal pin
4 DSR -> 4 --+
| diode resistor
6 DTR -> 6 --+---->|----/\/\/\---o kill power
1 DCD <- 1 --+
|
2 RxD <- 2 --+----------------+--o low battery
|
7 RTS -> 7 --------+--/\/\/\--+
|
+--/\/\/\--+
|
8 RI <- 8 --+----------------+--o on battery
|
9 CTS <- 9 --+
5 GND --- 5 ----------------------o ground
3 TxD 3 nc
</pre>
<h2>BackUPS ES and CS in Serial mode with Cable 940-0128A</h2>
Though these UPSes are USB UPSes, APC supplies a serial
cable (typically with a green DB9 F connector) that has
940-0128A stamped into one side of the plastic serial
port connector. The other end of the cable is a 10 pin
RJ45 connector that plugs into the UPS (thanks to
Dean Waldow for sending me a cable!).
Apcupsd version
3.8.5 and later supports this cable when specified as
<b>UPSCABLE 940-0128A</b> and <b>UPSTYPE backups</b>.
However, running in this mode much of the information
that would be available in USB mode is lost.
In addition, when <b>apcupsd</b> attempts to
instruct the UPS to kill the power, it begins
cycling about 4 times a second between battery
and line. The solution to the problem (thanks
to Tom Suzda) is to unplug the UPS and while it
is still chattering, press the power button
(on the front of the unit) until the unit beeps
and the chattering stops. After that the UPS
should behave normally and power down 1-2 minutes
after requested to do so.
<p>An amazing discovery by slither_man allows one
to build a CUSTOM-RJ45 cable (documented above) and
run the BackUPS CS (and probably also the ES) in
Smart mode. Running it this way provides all the
same information that you would get by running it
in USB mode. As a consequence, we recommend that you
either purchase (where I don't know) or build your
own CUSTOM-RJ45 cable rather than use the
940-0128A cable.
<p>Thanks to all the people who have helped test
this and have provided information on the
cable wiring, our best guess
for the cable schematic is the following:
<pre>
computer --------- Inside the Connector--------- UPS
DB9-F | | RJ45
pin - signal | | Pin - Color
| |
4 DSR ->|---+ |
| | diode resistor |
6 DTR ->|---+---->|----/\/\/\---o kill power | 8 Orange
| |
1 DCD <-|----+ |
| | |
2 RxD <-|----+----------------+--o low battery| 3 Brown
| | |
7 RTS ->|----------+--/\/\/\--+ |
| | |
| +--/\/\/\--+ |
| | |
8 RI <-|----+----------------+--o on battery | 2 Black
| | |
9 CTS <-|----+ |
| signal |
5 GND --|-----------------------o ground | 7 Red
| |
3 TxD | |
| chassis |
Chassis/GND |-----------------------o ground | 4 Black
| |
| Not connected | 1, 5, 6, 9, 10
--------------------------------------
The RJ45 pins are: looking at the end of the connector:
10 9 8 7 6 5 4 3 2 1
_______________________
| . . . . . . . . . . |
| |
-----------------------
|____|
</pre>
<h2>Win32 Implementation Restrictions for Simple UPSes</h2>
Due to inadequacies in the Win32 API, it is not possible
to set/clear/get all the serial port line signals. <b>apcupsd</b>
can detect: CTS, DSR, RNG, and CD. It can set and clear:
RTS and DTR.
<p>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.
<h2>Internal Apcupsd Actions for Simple Cables</h2>
<pre>
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:
condition = serial port initialization
cable = 0095A, 0095B, 0095C
action = ioctl(TIOMBIC, RTS) clear RTS (set PnP mode)
cable = 0119A, 0127A, 0128A
action = ioctl(TIOMBIC, DTR) clear DTR (killpower)
action = ioctl(TIOMBIS, RTS) set RTS (ready to receive)
apcserial.c:
condition = save_dumb_status
cable = CUSTOM_SIMPLE
action = ioctl(TIOMBIC, DTR) clear DTR (power bit?)
action = ioctl(TIOMBIC, RTS) clear RTS (killpower)
cable = 0020B, 0020C, 0119A, 0127A, 0128A
action = ioctl(TIOMBIC, DTR) clear DTR (killpower)
cable = 0095A, 0095B, 0095C
action = ioctl(TIOMBIC, RTS) clear RTS (killpower)
action = ioctl(TIOMBIC, CD) clear DCD (low batt)
action = ioctl(TIOMBIC, RTS) clear RTS (killpower) a second time!
apcserial.c:
condition = check_serial
cable = CUSTOM_SIMPLE
action = OnBatt = CD
action = BattLow = CTS
action = LineDown = SR
cable = 0020B, 0020C, 0119A, 0127A, 0128A
action = OnBatt = CTS
action = BattLow = CD
action = LineDown = 0
cable = 0023A
action = Onbatt = CD
action = BattLow = SR
action = LineDown = 0
cable = 0095A, 0095B, 0095C
action = OnBatt = RNG
action = BattLow = CD
action = LineDown = 0
apcserial.c
condition = killpower
cable = CUSTOM_SIMPLE, 0095A, 0095B, 0095C
action = ioctl(TIOMCBIS, RTS) set RTS (kills power)
action = ioctl(TIOMCBIS, ST) set TxD
cable = 0020B, 020C, 0119A, 0127A, 0128A
action = ioctl(TIOMCBIS, DTR) set DTR (kills power)
</pre>
<h3>RS232 Wiring and Signal Conventions</h3>
<p class="indent">
<table border="2" cellspacing="2" cellpadding="4">
<tr><th>DB-25
<br>Pin #</th> <th>DB-9
<br>Pin #</th> <th>Name</th> <th>DTE-DCE Description</th> </tr>
<tr><td>1</td> <td>--</td> <td>FG</td> <td>--- Frame Ground/Chassis GND</td></tr>
<tr><td>2</td> <td>3</td> <td>TD</td> <td>---> Transmitted Data, TxD</td></tr>
<tr><td>3</td> <td>2</td> <td>RD</td> <td><--- Received Data, RxD</td></tr>
<tr><td>4</td> <td>7</td> <td>RTS</td> <td>---> Request To Send</td></tr>
<tr><td>5</td> <td>8</td> <td>CTS</td> <td><--- Clear To Send</td></tr>
<tr><td>6</td> <td>6</td> <td>DSR</td> <td><--- Data Set Ready</td></tr>
<tr><td>7</td> <td>5</td> <td>SG</td> <td>---- Signal Ground, GND</td> </tr>
<tr><td>8</td> <td>1</td> <td>DCD</td> <td><--- Data Carrier Detect</td></tr>
<tr><td>9</td> <td>--</td> <td>--</td> <td>--- Positive DC test voltage</td></tr>
<tr><td>10</td> <td>--</td> <td>--</td> <td>--- Negative DC test voltage</td></tr>
<tr><td>11</td> <td>--</td> <td>QM</td> <td><--- Equalizer mode</td></tr>
<tr><td>12</td> <td>--</td> <td>SDCD</td> <td><--- Secondary Data Carrier Detect</td></tr>
<tr><td>13</td> <td>--</td> <td>SCTS</td> <td><--- Secondary Clear To Send</td></tr>
<tr><td>14</td> <td>--</td> <td>STD</td> <td>---> Secondary Transmitted Data</td></tr>
<tr><td>15</td> <td>--</td> <td>TC</td> <td><--- Transmitter (signal) Clock</td></tr>
<tr><td>16</td> <td>--</td> <td>SRD</td> <td><--- Secondary Receiver Clock</td></tr>
<tr><td>17</td> <td>--</td> <td>RC</td> <td>---> Receiver (signal) Clock</td></tr>
<tr><td>18</td> <td>--</td> <td>DCR</td> <td><--- Divided Clock Receiver</td></tr>
<tr><td>19</td> <td>--</td> <td>SRTS</td> <td>---> Secondary Request To Send</td></tr>
<tr><td>20</td> <td>4</td> <td>DTR</td> <td>---> Data Terminal Ready</td></tr>
<tr><td>21</td> <td>--</td> <td>SQ</td> <td><--- Signal Quality Detect</td></tr>
<tr><td>22</td> <td>9</td> <td>RI</td> <td><--- Ring Indicator</td></tr>
<tr><td>23</td> <td>--</td> <td>--</td> <td>---> Data rate selector</td></tr>
<tr><td>24</td> <td>--</td> <td>--</td> <td><--- Data rate selector</td></tr>
<tr><td>25</td> <td>--</td> <td>TC</td> <td><--- Transmitted Clock</td></tr>
</table>
</p>
<p>
<h4>Pin Assignment for the Serial Port (RS-232C), 25-pin and
9-pin, Female End</h4>
<P><PRE>
13 1 5 1
_______________________________ _______________
\ . . . . . . . . . . . . . / \ . . . . . / RS232-connectors
\ . . . . . . . . . . . . / \ . . . . / looking into the
--------------------------- ----------- end of the cable.
25 14 9 6
The diagram above represents the Female end of the cable. The
male end is the same, but looking from inside the cable.
DTE : Data Terminal Equipment (i.e. computer)
DCE : Data Communications Equipment (i.e. UPS)
RxD : Data received; 1 is transmitted "low", 0 as "high"
TxD : Data sent; 1 is transmitted "low", 0 as "high"
DTR : DTE announces that it is powered up and ready to communicate
DSR : DCE announces that it is ready to communicate; low=modem hang-up
RTS : DTE asks DCE for permission to send data
CTS : DCE agrees on RTS
RI : DCE signals the DTE that an establishment of a connection is attempted
DCD : DCE announces that a connection is established
</PRE>
<P></P>
<H2><A name=ioctl></A>Ioctl to RS232 Correspondence</H2>
<P>
<BLOCKQUOTE><PRE>
#define TIOCM_LE 0x001
#define TIOCM_DTR 0x002
#define TIOCM_RTS 0x004
#define TIOCM_ST 0x008
#define TIOCM_SR 0x010
#define TIOCM_CTS 0x020
#define TIOCM_CAR 0x040
#define TIOCM_RNG 0x080
#define TIOCM_DSR 0x100
#define TIOCM_CD TIOCM_CAR
#define TIOCM_RI TIOCM_RNG
#define TIOCM_OUT1 0x2000
#define TIOCM_OUT2 0x4000
</PRE></BLOCKQUOTE>
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