[time-nuts] Meinberg DCF77 C51 - serial connection?

[Rune Magnussen]

fre, 12 01 2007 kl. 17:40 +0000, skrev James R Miller:
> Dear Rune,
> 
> Serial ports /never/ work as expected.  Not infrequently this is due to
> misleading documentation.
> 
> Thus, referring to the information on the manual page 15, the service name on
> pin 2 should be TXD and that of pin 3 should be RXD.  That they are wrongly
> shown /might/ be a clue.
> 
> If the unit is configured to look like a modem (DTE), then the connector
> should be male, and data would be transmitted by it on pin 3.
> 
> If the unit is configured as a computer (DCE), then the connector should be
> female, and data would be transmitted by it on pin 2
> 
> My advice is to check what you actually have - not what the handbook says you
> should have!  Put a voltmeter or scope on pin 3, and see if you have +/-6V
> (typ) data pulses.  And if the connector is male, then you have a correctly
> wired "modem", with all that implies for normal interconnections.
> 
> If you do not have the above, the you will have to improvise.  The probability
> of this is close to 1/2.
> 
> Hope useful!
> 

Dear James.

I received the following from Meinberg:

enclosed you receive the SUB-D Pin Assignment of the DCF77 C51
as well as Pin Assignments of the PC interface.

DCF77C51                        PC(9pol.)

Pin 2  -->  RxD              ----      Pin 3  -->  TxD
Pin 3  -->  TxD              ----      Pin 2  -->  RxD
Pin 7  -->  GND              ----      Pin 5  -->  GND


Do you try to connect to the serial port directly with a
terminal program: set the parameters to 9600 Baud 7E2
no hardware handshake. Every second you have to see a
32 character string with the time and date and some
status informations.

Also it is important for the NTP that the DCF clock
has synchronized: the red LED (Freilauf) must be off.

[snip - ntpd conf]

****

I use a standard modem cable (25 pin male / 9 pin female). Does the
described pinout mean it is like a computer?
Since I got the unit there has been trouble detecting the signal. Looks
like I was just lucky at startup. So testing is not going as smoothly as
I hoped for. I will try the suggested test via minicom ons there is a
good signal again.

Using Google I have not found anything about Meinberg DCF77 C51 and
strange pinouts.

Regards Rune