[time-nuts] Z3805 utility, Was: AW: (no subject)

[Steve Rooke]

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 <jeffhook at comcast.net> 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" <rbenward at verizon.net>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> 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" <jeffhook at comcast.net>
>> To: "Discussion of precise time and frequency measurement"
>> <time-nuts at febo.com>
>> 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"
>>> <stanley_reynolds at yahoo.com>
>>> To: "Discussion of precise time and frequency measurement"
>>> <time-nuts at febo.com>
>>> Sent: Sunday, May 23, 2010 3:56 PM
>>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject)
>>>
>>>
>>>
>>>
>>>
>>>
>>> ----- Original Message ----
>>> From: Jeff Hook <jeffhook at comcast.net>
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at febo.com>
>>> 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
>>>
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>>
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>
>
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-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.