not sure how would one connect 2 pi's with AB cable or A - mini cable .. A - micro might even work not sure ..
but I think 2 rpi's is not a solution, I think it should be a test one can run on actual target system... I can test a cable locally, 40GHz spectrum analyzer, 5G pulse generator, 40GHz scope and I can look at the eye and see what's up there.. but not something I can do "on prem" at a "customer site"
I was thinking more about
- connect to printer
- send ton of #^#@% to printer, long (in characters) commands (G91, G0 X000.0000 Y000.0000 Z000.0000 F000.00000 E000.00000 ...) and introduce some actual "dancing moves" (G0 X001.0000 Y001.0000 Z0001.0000, G0 X-001.0000 Y-001.0000 Z-0001.0000) and some disable/enable steppers (biggest EMI producer) .. all with checksum of course
- send ton of "mini" gcodes (G0X0 for e.g.)
- collect statistic about
- requests for retry
- timing of each reply
- monitor dmesg , /var/log/messages ... while doing it
so we get as result both test of a cable and some info about max troughput from octoprint to printer (and back)...
and all that as part of octoprint (plugin)
I know how I'd do it in C outside of octoprint but the idea is to do the whole thing trough octoprint by octoprint's serial library to get the actual numbers octoprint related... a section of it might be external to octoprint (e.g. 30min run of "G0X0" at max system speed, to test cable) but most of it should go trough all octoprint layers.. and that's the part I have no clue how to do