From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Deepak Gupta" Subject: RE: serial communication problems Date: Thu, 30 May 2002 08:25:20 +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 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----- =46rom: 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 Linux > (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 pair > (multidrop) and this line terminates in a 485-232 converter box which > is connected via the serial line to a PC. The lock vendor has suppli= ed > a Windows software to program the locks which works fine on this PC. > He has also given me the protocol that is followed between the PCs an= d > 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 loc= k > it replies obediently but when my program writes exactly the same seq= uence > 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). > 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 contr= ol > (RTS/CTS) but no luck. I know that the command I send is right since > I used another PC to listen to what the vendor software writes on the > 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-seria= l" 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 - 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