[ntp:questions] Meinberg DCF77 C51 with Linux 2.6

Maurice Janssen mauricej at xs4all.nl
Sat Feb 10 19:35:08 UTC 2007

On Sat, 10 Feb 2007 19:55:31 +0100, Rune Magnussen wrote:
>Den Sat, 10 Feb 2007 18:29:15 +0000. skrev Maurice Janssen:
>> Have you tried without the null-modem cable?  IIRC you need a straight
>> cable (like you would use between computer and external modem).
>Yes. Since it did not work I contacted Meinberg and found out that I
>needed a cable with pins 2 and 3 crossed. That is a null-modem cable right?

That depends on the type of connector (25 or 9 pins), they don't have
the same order (pin 2 and 3 are switched, just to make things more

Looking at the data sheet of the C51, pin 3 is the TX pin.  On a 9 pin
serial port on the PC, this needs to be connected to pin 2 (RX).
But this is not a null-modem cable but a straight cable.

The standard setting for the C51 is rather unusual (7E2) compared to the
more common setting (8N1).  Perhaps that is the problem?


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