Hey all, I've been working on debugging a stubborn issue with a TDS 745C scope, and it's been suggested that I can get some useful debug information out of the TDS debug port. I got my hands on the adapter documented in this thread:
https://www.eevblog.com/forum/testgear/console-port-debug-adapter-for-tek-tds500-tds600-and-tds700-series-scopes/I also have a number of serial/USB adapters lying around, and I've tried several of them with this adapter, but I haven't managed to get an output from the scope. In fact, the scope exhibits the behavior reported in that thread where it won't boot at all. My process is:
1) Connect the serial/USB adapter to my computer.
2) Connect to the adapter via picocom -b 9600 /dev/ttyUSB0 -f h
3) Verify the picocom configuration:
*** baud: 9600
*** flow: RTS/CTS
*** parity: none
*** databits: 8
*** stopbits: 1
*** dtr: up
*** rts: up
*** mctl: DTR:1 DSR:0 DCD:0 RTS:1 CTS:0 RI:0
4) Boot the scope
The scope remains stubbornly blank, apparently waiting for some serial signal I have failed to send, though I believe that RTS/CTS flow control is all that is required. For sanity's sake, I shorted the CTS and RTS pins to each other, and this did in fact get the scope to boot, but rather than debug info I just received gibberish over the serial connection (the random question marks and escape characters that generally show up with an incorrect baud rate). What's really interesting about this, is that the gibberish continued even after I turned the scope off, so I'm wondering if I'm running into some sort of buffering behavior? My next step is to plug in am FTDI USB/serial breakout with RTS/CTS pins exposed and see if I can get any useful debug information via a logic analyzer, but I'm hoping someone here might have some clue as to what is going on.
[edit] Used my logic analyzer, and I am in fact observing readable ASCII output. However I get no output on the serial client for some reason. However, I was playing around and reversed TX/RX, and suddenly the serial client started outputting gibberish, though at a rate that indicates I was just seeing the garbled debug output. So garbled output with the pins reversed, no output with the pins in the correct spot.