Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!tut.cis.ohio-state.edu!ucbvax!WSMR-SIMTEL20.ARMY.MIL!w8sdz From: w8sdz@WSMR-SIMTEL20.ARMY.MIL (Keith Petersen) Newsgroups: comp.sys.ibm.pc Subject: Problem with serial port Message-ID: Date: 25 Feb 89 20:03:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 32 foote@ernie.Berkeley.EDU (Bill Foote) writes: > I have a problem with my serial port (on my Unisys AT clone). I > can't send output to it using fopen("com1:", "w") from Microsoft > C, and "copy con: com1:" doesn't work (it accepts keyboard input, > but nothing comes out of the serial port). When I type in > "mode com1:12,N,8,1" (or even just "mode com1:"), I get the error > message "invalid parameter com1". Despite this, Procomm, Telix, and > Crosstalk XIV all have no trouble with the serial port, and my > diagnostics disk tells me that I do indeed have a serial port > installed. Does anyone have any idea what might be wrong? Bill, the problem is that you have to turn on DTR (and maybe CTS/RTS handshaking if the modem wants to see that). If you get file pd1:DOSMODEM.ARC from Simtel20 and run DTR.COM in your AUTOEXEC.BAT file you will be able to do simple things like ECHO string>COM1 without getting the abort/retry/fail message. There is another file in that archive called AT.COM which sends Hayes-compatible "AT" command to the modem. AT Z sends ATZ to reset the modem. AT DT555-1212 will dial that number etc. The default baud rate for the PC's COM ports is 2400. --Keith Petersen Maintainer of the CP/M & MSDOS archives at wsmr-simtel20.army.mil [26.0.0.74] DDN: w8sdz@wsmr-simtel20.army.mil Uucp: {ames,decwrl,harvard,rutgers,ucbvax,uunet}!wsmr-simtel20.army.mil!w8sdz