Hi. I'm not sure if it have been mentioned, but I would look for a software instead of a hardware solution becuse of the extra PIC I/O pin(s) "wasted"... Like some special character sequesnce to "open the line", and always expect echo's to detect "line down". Jan-Erik. Genome skrev: > I'm thingking of setting DTR on from the PC side when connecting and then > the device on the other end should reply by setting DSR on.. and keep them > on while connected. just like a modem.. to detect a connection and sudden > disconnection.. im thinking of always querying this pins before sending and > receiving couple it with some error handling routine to tell if the cable is > good or not. > > thanks everyone for all your inputs.. > > ----- Original Message ----- > From: "Gerhard Fiedler" > Newsgroups: gmane.comp.hardware.microcontrollers.pic > Sent: Monday, October 23, 2006 5:40 AM > Subject: Re: [PIC]RS-232 on the pc side > > >> Genome wrote: >> >>>> Keep sending data suppose 0x55,0x01 and wait for response. >>> My problem with the keep sending data is that there is no way of telling >>> when the pic is suddenly disconnected in the middle of a communication.. >>> i.e. the pic will just think that there are errors and no way of telling >>> whether the error is due to cable disconnection or just transmission >>> errors... I would like something like plugAndplay capability... >> Not even with DTR or any other signal you will be able to tell whether the >> error is due to cable disconnection or transmission error (say a broken >> cable or a pin with bad contact). >> >> Usually there is a problem that you should solve anyway when you have a >> significant number of transmission errors (as in scrambled bits) in a >> wired >> short-range serial link. >> >> Even though you can, you probably shouldn't have to deal with additional >> status lines. Sending out a "start of transmission" marker and waiting a >> short time seems good enough to me, too. >> >> You also didn't say on what side you want to detect the presence of a >> connected device. If you want to know at the PC side whether there's >> something connected at the serial port, the PC's DTR output doesn't seem >> to >> be the one you need -- an input (CTS, DSR, CT) would probably be better >> suited. >> >> Gerhard >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist