use ground, txdata, rxdata only. on connector, tie rts,cts together. dsr, dtr, and carrier detect together. on db25, thats 4 - 5, 6 -8- 20, ground 7, tx 2, rx 3. pc sends on 2, receives on 3. I usually connect 1 and 7 both for ground(common) Martin Peach wrote: > > Not totally certain but I think DTR to DSR, DCD is not used. > In Windows you can use either CTS/RTS or DTR/DSR for hardware handshaking. > Often the PC's CTS is connected to its own RTS at the remote end of the > cable (to verify that a cable is plugged in) and DTR/DSR are usd to gate the > data flow. > /\/\/\/*=Martin > > ----- Original Message ----- > From: "Bob Barr" > To: > Sent: Tuesday, November 20, 2001 11:50 AM > Subject: [EE]: RS-232 connections > > I'm interfacing a device to the RS-232 port on a PC and would > appreciate suggestions regarding the required connections. > > I've got a 9-pin female connector on the device and I'm using a > straight-through female-to-male cable from the PC to the device. > > So far, I have ground, device Txd and device Rxd on pins 5, 2, and 3 > respectively. I can communicate to and from the device with ProComm. > So much for the easy part. :=) > > My real issue is looping back the handshake lines to most easily > interface to a PC. I'd like to avoid forcing any changes to the PC's > default handshake settings. For this application, I don't need any > hardware handshaking so I'm planning to jumper the appropriate pins > together at the device. > > I'm fairly certain that RTS and CTS (pins 7 and 8) need to be > connected. Should I also make a connection between DCD, DTR and DSR > (pins 1, 4, and 6)? (DCD to DTR looks most likely but I'm not at all > sure about that.) > > Any suggestions? > > Thanks, Bob > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.