I have received the Trimble version of this reference, with all of the work already done to build it into an enclosure (similar to the BG7TBL).
I have not been able to figure out the data communication. (I posted previously here initially just being confused about basic serial comms:
https://www.eevblog.com/forum/beginners/rs232-rx-vs-tx/)
What I think the builder has done (he uses the 50-pin ribbon cable exclusively) is to route the Trimble's debugging serial port pin 37 Tx to a feedthrough cap, then to a Sipex RS232 level converter chip, then to another feedthrough cap, and then back into the usual communication port pin 33 Rx. The same routing happens with the sibling Rx/Tx ports.
What's interesting is that the RS232 data right out of the Sipex chip looks like normal data you'd expect (TxD (57600 8N1) binary protocol, each 2 seconds bytes that seen as on "TOD EN" command are sent using this port. It's duration is 8ms every second with ±5V levels), but after the cap all of the the signal edges turn into very short pulses (±5V levels) on pin 33 Rx. Those pulses appear on the device RS232 RX pin interface connector as well as Trimble's J5 pin 1 Rx. The TX pin is -5V at J5 pin2 and on the device RS232 Tx pin. So something is happening through that cap or signals on the Trimble board are working to cancel each other out.
The LEDs on the Trimble unit blink mostly as described earlier in this thread, with the ACT and ALM leds briefly red on power-up, then the ACT goes steady green, then starts slow flashing (I see it more as toggling between red and green). If I press the MACT button the ACT led will flash quickly for maybe 20 seconds, then start flashing slow again. I think it's trying to lock. If I leave it long enough, the ACT led will flash quickly, and I think that means it's locked.
My main question now is how should I proceed to try and get communications working and figure out if the unit is really locking? I have considered unsoldering the feedthrough caps connected to pins 33/34 Rx/Tx or perhaps removing the Trimble unit entirely from the builders board and interfacing with J5. But I am wondering about the -5V on the Trimble's Tx pin. Does the Trimble usually transmit or does/can it be configured to not transmit unless commanded to do so? I'm certain I am going to have to disconnect something to remove those pulses from the Rx pins before I can send anything to it.
Thanks