Hi, I rewired the cable and it works:
RxD 2 ------------------- 3 TxD TxD 3 ------------------- 2 RxD DTR 4 ------------------- 6 DSR DSR 6 ------------------- 4 DTR RTS 7 7 RTS | | CTS 8 8 CTS | | DCD 1 1 DCD In other words, RTS, CTS and DCD are connected locally on both ends. Possibly not one of the greatest breakthroughs in Information Technology, but hey, I'm not one of the Hardware Guys.. By the way, I found 4.48V on the RTS pin on a Soekris box in idle state. CTS and DCD were both 0V. Apparently the UART on the Soekris box is in RTS/CTS flow control mode, as RTS is presumably pulled low (given cu's behaviour) after a character has been processed. IMHO this should not happen, or else be mentioned in the docs. Bill On Tue, 2007-10-23 at 17:03 +0200, Bill Maas wrote: > Hello Bernd, > > On Tue, 2007-10-23 at 12:22 +0200, Bernd Walter wrote: > > On Mon, Oct 22, 2007 at 11:27:15PM +0200, Bill Maas wrote: > [...] > > > I can't see what a Soekris box has to do with the DCD line, however. > > > > If you configured your terminal/serial correctly for 3-wire then it > > shouldn't care about DCD at all. > > Here's the serial port setup: > > [EMAIL PROTECTED]:~# stty -F /dev/ttyS0 -a > speed 9600 baud; rows 0; columns 0; line = 0; > intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; > eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; > susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O; min = 1; > time = 0; > -parenb -parodd cs8 hupcl -cstopb cread clocal -crtscts > -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon > -ixoff -iuclc -ixany -imaxbel -iutf8 > opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 > vt0 ff0 > isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop > -echoprt echoctl echoke > > > As the stty ouput shows, RTS/CTS flow control is turned off - but that's > on this side of the connection. Man page cu(1) hardly mentions > handshake, only for debugging. DCD isn't mentioned at all (but see > below..). Running 'cu' in debug mode hardly increases it's output: > > ------------------------------------------------------------------------ > [EMAIL PROTECTED]:~# cu -d -l /dev/ttyS0 -s 19200 > cu: fconn_open: Opening port /dev/ttyS0 (speed 19200) > cu: fconn_set: Changing setting to 0, 0, 2 > Connected. > cu: Got hangup signal > cu: Exit status 0 > cu: fconn_close: Closing connection > > Disconnected. > [EMAIL PROTECTED]:~# cu -x handshake -l /dev/ttyS0 -s 19200 > Connected. > cu: Got hangup signal > > Disconnected. > ------------------------------------------------------------------------ > > The soekris docs don't mention handshaking modes either. > > > > The other point is that you likely don't have the correct 0-modem > > cable to supply a DCD signal into your computer. > > It might be that DCD input is open and floating. > > > > Cable is wired as follows: > > RxD 2 ------------------- 3 TxD > TxD 3 ------------------- 2 RxD > > DTR 4 ------------------- 6 DSR > DSR 6 ------------------- 4 DTR > > RTS 7 / 8 CTS ----------- 1 DCD > 1 DCD ----------- 7 RTS / 8 CTS > > Apparently the Soekris comBIOS drops the voltage on its RTS/CTS pair > once a character arrives, which 'cu' sees as a hangup signal. > > > I wouldn't know where to go from here, but here's something very > interesting I found about IBM's cu (command options): > > -m Instructs the cu command to ignore modem control signal data > carrier detect (DCD). > > (http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds1/cu.htm > ) > > Seems to be exactly what I am looking for. Unfortunately this option is > missing in the Linux version. And I'm still not convinced that the > Soekris comBIOS should be touching those RTS/CTS lines.. > > Thanks for the reply anyway, at least it gave me something to look for. > > Meanwhile, every piece of soft- or hardware I touch today seems to > immediately disintegrate:-( > > > Bill > > -- "Ask not what it's for, ask what you can do with it." _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
