[time-nuts] Symmetricom TimeSource 2700
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Thu Nov 24 23:17:16 EST 2011
>I use the Craft connector for monitoring with BTMon rather than the
>It appears the Craft output, while spontaneously emitting
>alarm/events, does respond
>to queries from BTMon on the Craft input.
Everything I reported previously involved the Craft port feeding a PC
COM port using the RJ45-to-DB9 cable supplied by Symmetricom.
>Do you happen to have a RS-422/485 interface? I don't, but I'm
>interested to see
>if any spontaneous output occurs on the TOD port.
I have a 422/485 card here somewhere, but I haven't used it (maybe
even seen it) in more than 10 years.
I poked a scope at the TOD jack. The TS2500 manual says that (in a
TS2500) Pin 1 should be PPS (positive), Pin 6 should be PPS
(negative), Pin 5 should be TXA output (positive), Pin 9 should be
TXA output (negative), and Pins 7 and 3 should be a 20 V external
supply positive and return, respectively.
I found PPS positive and negative on Pins 1 and 6. Logic low is
about 1.2 V positive with respect to case ground, and logic high is
about 3.8 V above case ground, for a logic range of approximately 2.6
V. The PPS pulses are 500 uS wide with rise and fall times of ~20-25 nS.
I did not see any data on the TXA outputs -- the positive TXA output
just sits at logic low and the negative TXA output sits at logic high.
There is 20 V between Pins 7 and 3. As for the unspecified pins --
Pin 2 sits at nominally 0 Vdc, and Pins 4 and 8 sit at nominally
0.168 Vdc. All three have around 20 mVp-p of hum and noise.
While I was at it, I poked at the RS232 connector, as well. Pin 3
(TX Data) has a 16 or 17 mS burst of data every 5 seconds
(approximately), from -10 V to +10 V with respect to case
(henceforth, 232 low and high, respectively). Between bursts, it
sits at 232 low. Pins 4 and 7 (DTR and RTS, respectively) sit at 232
high. All other pins sit at ground.
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