There really is no mystery in any of this. There are two types of equipment, a Data Terminal Equipment, DTE, and a Data Communications Equipment, DCE. A DTE refers to the end controlling terminal as in a computer, teletype, dum terminal, green screen, et al. It should have a mail connector on it, whether 25 pin or 9 pin, and this is your first clue as to what the item is. This is an easy way to differentiate it from the 25 pin female connector on the back of a PC which we all know is for parallel. The minimum connections for a DTE are for a 25 way connector, pin 2 Rx, Pin 3 Tx and Pin 7 Signal ground/common. Now on a 9 way connector the transmission pair pins are pin 2 Rx, pin 3 Rx and pin 5 Signal Ground.
Seeing as how a PC and the Z3805A are both a DTE, this means we need:- 9 DSUB <-> 25 DSUB 2 <- 3 3 -> 2 5 <-> 7 Which is the off-times called null-modem connection but as you can see it caters solely for a simple 3 wire connection. If you need to have a full hardware handshake between DTE <-> DTE or DCE <-> DCE, then things can become a little more interesting depending on how pedantic the control circuits of the input circuits manifest themselves. Other notable DTE communication signals are, for a 25 way DSUB, pin 4 Request To Send, RTS, output, pin 5 Clear To Send, CTS, input and pin 8 Carrier Detect, CD, input. Look up the equiv 9 DSUB if you need to. For a DCE, the DSUB connector should be a female and is, again, the first sign of the type of equipment. To connect a DTE to a DCE, the easiest, we just use a straight cable, pin for pin in the same DSUB size or 2 <- 2, 3 -> 3 and 5(7) <-> 7(5) as a minimum. All the other pins for 25 DSUB (9 DSUB) go straight 4(7) -> 4(7), 5(8) <- 5(8) and 8(1) <- 8(1), assuming the DTE is on the right and DCE is on the left of the descriptions. Steve On 24 May 2010 11:09, Jeff Hook <[email protected]> wrote: > Bob, > Serial ports have always been tough to get working right. > I guess I shouldn't call a serial cable, a straight cable. > I just want to differentiate it, from a null modem cable. > > I made up my own cables when I got my Z3805A's > 9pin on computer end and 25 pin on 3805 > I wired 2-2, 3-3, and 5-7 and it worked. > > Their is also a program called GPS-dos2 that you can download from > http://www.realhamradio.com/gps-satstat-software.htm > It runs thru all baud rates, trying to communicat with the 38xx > You could give that a try. > > Jeff > > ----- Original Message ----- From: "Robert Benward" <[email protected]> > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Sent: Sunday, May 23, 2010 4:41 PM > Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) > > >> Jeff, >> A plain serial cable will have 2&3 swapped, a "straight through" is 2-2 >> and 3-3. There were a lot of DB25 to DB25 that were NOT serial cables, they >> were just 25 pin cable using DB9. >> >> Bob >> >> >> ----- Original Message ----- From: "Jeff Hook" <[email protected]> >> To: "Discussion of precise time and frequency measurement" >> <[email protected]> >> Sent: Sunday, May 23, 2010 5:24 PM >> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) >> >> >>> Receive data is pin 2 on DB9 and 3 on DB25 >>> Transmit data is Pin 3 on DB9 and 2 on DB25 >>> A straight thru cable with DB9 on one end and DB25 on the other will have >>> pins 2 and three crossed >>> A null modem cable, that is required for a Z3805A, will be pin 2 to pin 2 >>> and pin 3 to pin 3 >>> >>> Jeff >>> ----- Original Message ----- From: "Stanley Reynolds" >>> <[email protected]> >>> To: "Discussion of precise time and frequency measurement" >>> <[email protected]> >>> Sent: Sunday, May 23, 2010 3:56 PM >>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) >>> >>> >>> >>> >>> >>> >>> ----- Original Message ---- >>> From: Jeff Hook <[email protected]> >>> To: Discussion of precise time and frequency measurement >>> <[email protected]> >>> Sent: Sun, May 23, 2010 12:42:45 PM >>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) >>> >>> Bob >>> My 3805 cables look like this >>> >>> DB9 DB25 >>> 2 2 >>> 3 3 >>> 5 7 >>> (Null Modem) >>> >>> Jeff >>> >>> <snip> >>> >>> straight cable is 2 to 2 to 3 to 3 >>> >>> null modem would be >>> >>> 2 3 >>> 3 2 >>> >>> normal usage would be: >>> >>> terminal (straight cable) modem (phone line) modem (straight cable) >>> computer >>> computer (straight cable) modem (phone line) modem (straight cable) >>> computer >>> >>> or if no modems : >>> >>> terminal (null modem) computer >>> >>> As has been mentioned many exceptions to the rule. >>> >>> Stanley >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
