From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Deepak Gupta" Subject: RE: serial communication problems Date: Thu, 30 May 2002 12:10:47 +0530 Sender: linux-serial-owner@vger.kernel.org Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: List-Id: linux-serial@vger.kernel.org To: Gerald Emig Cc: linux-serial@vger.kernel.org Thanks for the response. I tried lowering RTS after sending the data and raising it again before the next try (using calls ioctl(fd, TIOCMBIC/TIOCMBIS, ...)). But no luck. When I debugged the program, and looked at /proc/tty/driver/serial at breakpoints, I observed (as expected) that RTS is high when sending and low after sending. I'm feeling desperate, please help ..... Deepak -----Original Message----- =46rom: Gerald Emig [mailto:gme@heisch.inka.de] Sent: Thursday, May 30, 2002 12:21 PM To: Deepak Gupta Subject: RE: serial communication problems If it is such a converter box as you wrote, RTS probably only may activ= e if your program is sending. If it stays active after that, you can not receive any data, because RTS switches between receive and transmit of = the box. On Thu, 30 May 2002, Deepak Gupta wrote: > RTS is active as reported by /proc/tty/driver/serial. > In fact all three of RTS, CTS, and DTR are shown active. > > What else could be wrong? > > Deepak > > -----Original Message----- > From: Gerald Emig [mailto:gme@heisch.inka.de] > Sent: Wednesday, May 29, 2002 7:37 PM > To: Deepak Gupta > Cc: linux-serial@vger.kernel.org > Subject: Re: serial communication problems > > > On Wed, 29 May 2002, Deepak Gupta wrote: > > > Hi, > > > > I have a strange problem with the serial line communication in Linu= x > > (RH 7.2, kernel 2.4.7-10). We have some electronic locks that are > > controlled by a PC. The locks are connected by a RS485 twisted pai= r > > (multidrop) and this line terminates in a 485-232 converter box whi= ch > > is connected via the serial line to a PC. The lock vendor has supp= lied > > a Windows software to program the locks which works fine on this PC= =2E > > He has also given me the protocol that is followed between the PCs = and > > the locks. I am trying to write my own Linux based software for > > programming the locks. > > > > The problem is that when the vendor software sends a command to a l= ock > > it replies obediently but when my program writes exactly the same sequence > > of bytes to the serial line, I don't get a response (the protocol > > says that the lock will not respond unless it gets a valid command)= =2E > > I know the locks use 9600 baud, 8 bits, no parity, 1 stop bit and I > > am using the same. I also tried with and without hardware flow con= trol > > (RTS/CTS) but no luck. I know that the command I send is right sin= ce > > I used another PC to listen to what the vendor software writes on t= he > > serial line and it matches the protocol description that I have. > > > > Incidentally I opened up the 232-485 converter box and saw that it > > uses only the TX, RX, SG, RTS and CTS lines on the RS232 side. So > > it cannot be a matter of DTR or some other signal. > > > > I had a similar problem a few days ago. > Old software worked, new one did not. > So I also used a third PC to look what the others talk. > I noticed the same as you. > > Solution was that RTS had to be set active. > > > > Please help. > > > > Deepak Gupta > > - > > To unsubscribe from this list: send the line "unsubscribe linux-ser= ial" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > Gerald Emig > > -- > EMIG Software Tel. 06858-6197, Mobil: 0163-4751706 > Engelstr. 17 Fax. 0721-151-348672 > 66564 Ottweiler-F=FCrth http://sites.inka.de/heisch > Germany e-mail: gme@heisch.inka.de > > > Gerald Emig -- EMIG Software Tel. 06858-6197, Mobil: 0163-4751706 Engelstr. 17 Fax. 0721-151-348672 66564 Ottweiler-F=FCrth http://sites.inka.de/heisch Germany e-mail: gme@heisch.inka.de - To unsubscribe from this list: send the line "unsubscribe linux-serial"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html