<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <html> <head> <title>Apcupsd Cable Configuration</title> <meta name="Author" content="Kern Sibbald"> <link rel=stylesheet href="apcupsd-styles.css" type="text/css"> </head> <body> <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). It is easy to construct the cable by cutting off one end of a standard RJ45-8 ethernet cable and wiring the other end (three wires) into a standard DB9F female serial port connector. <p> 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> For the serial port DB9F connector, the pin numbers are stamped in the plastic near each pin. In addition, there is a diagram near the end of this chapter. <p> 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 at 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> <hr> <a href="config-examples.html" target="_self"><img src="back.gif" border=0 alt="Back"></a> <a href="invoking.html" target="_self"><img src="next.gif" border=0 alt="Next"></a> <a href="index.html"><img src="home.gif" border=0 alt="Home"></a> </body> </html>