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

Steve Rooke sar10538 at gmail.com
Mon May 24 02:39:39 UTC 2010


Takes foot out of mouth!!!

On 24 May 2010 14:08, Steve Rooke <sar10538 at gmail.com> wrote:
> 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 3 Rx, pin 2 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 <- 2
3 -> 3
5 <-> 7

>
> Which is off-times called a 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 25 DSUB
size or 2 <- 2, 3 -> 3 and 7 <-> 7 as a minimum. All the other
pins for 25 DSUB go straight 4 -> 4, 5 <- 5 and
8 <- 8, assuming the DTE is on the right and DCE is on the left
> of the description.

When i worked for BT way, way back, we came up with a 9 way DSUB
connection that made it easy to match with a 25 DSUB. If you take a
piece of 25 way ribbon cable and clamp it in a crimp 25 DSUB and the
cut out all but the first 9 wires from pin 1, you then clamp the other
end of the 9way ribbon in a 9 DSUB. It does not match the current 9
DSUB standard but it was just doen internally by us. It sure made it
easy to make up internal interconnects on equipment and cheap external
cables.

Sorry for the senior moment, hope I have it right now (blessed 9 way pinouts!!!)

Steve
>
> 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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>>
>>
>>
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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.
>



-- 
Steve Rooke - ZL3TUV & G8KVD
A man with one clock knows what time it is;
A man with two clocks is never quite sure.



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