Just what any good resurrections project would need: How about some dumps of info found from monitoring COM ports, and checking the resistance and voltage between pins on a data cable? 

I found out that:

Signal is sent back and forth in hex that's sometimes translatable to text. For instance, when idling, the log 

9701 09/07/2023 14:33:49 IRP_MJ_WRITE UP STATUS_SUCCESS 45 56 53 63 6f 6e 74 72 6f 6c 6c 65 72 05 03 66 06 00 00 00 00 00 00 00 00 00 00 00 00 49 52 4f 4c 44  

Translates to: 

EVScontroller..f.............IROLD 34  COM3  

EVS is the name of the company that first made this system before it was bought by GE. It is likely that "f", or any of several other characters like from "IROLD", is representative of state information like motors running, That string of 0s, by the way, is filled in when doing something. When moving a motor:

10884 09/07/2023 14:56:19 IRP_MJ_WRITE DOWN  45 56 53 63 6f 6e 74 72 6f 6c 6c 65 72 ff 03 66 06 20 3a 98 23 28 30 d4 02 58 c0 02 00 49 52 4f 4c 44  EVScontrollerÿ.f. :˜#(0Ô.XÀ..IROLD 34 34 COM3  

When turning on the source:

12570 09/07/2023 15:38:29 IRP_MJ_WRITE DOWN  45 56 53 63 6f 6e 74 72 6f 6c 6c 65 72 02 03 66 06 00 27 10 1d 4c 27 10 06 26 c0 00 00 49 52 4f 4c 44  EVScontroller..f..'..L'..&À..IROLD 34 34 COM3  

Any ideas about translating the code, let me know. I did not see a difference when trying 40 vs. 45 or 60 kv. Maybe the software always sends the same signal like 40 kv at first, and then when receiving a stable voltage ramps. 

in addition, there are signals sent back from the scanner that display basic info in one unit of hexadecimal. For instance, I saw messages like '80' which means 'manual x-ray switch is off', '40' which means "safety door opened", and '04', which means "left switch activated" ( it only checks one axis at a time --- I guess they never move the motors together anyway). I can also see how it tells which motor is active, but again, not what it is actually telling to do. 

My immediate goal, was to be able to send a signal lower than 40kv to start --- the tube is rated to 20kv at max current, and probably works at all at a lower voltage. Rather than potentially destroy my tube getting up to 40kv, I'd rather start with a voltage that actually can reach, and maybe keeping it stable there will help it even condition to higher voltages. 

The other idea is to look at the actual signal in the cable (#1)/pinout. It has 13 pins. I needed both hands, so I took notes by the incredibly annoying use of voice to text on my phone  texting myself which was stupid and annoying. 

Resistance: 

1 is 800 ohm with 2, 900 with 3, 10 ohms with 4, 900 with 5, all others mega ohm range

2 is 100 ohms with three, 900 with 4, 2000 with 5, all others mega ohm range

3 is 1k with four, 2k with five

4 is 1k to 5

everything else is mega ohm range. 

Voltage and grounds: Pin 1 is ground to rest of the machine, and pin four is connected to ground through 10 ohms. 

The voltage and current which fluctuates on the display when the cable isn't connected, stops fluctuating (shows 0) when pin 7 is connected to ground (voltage) and 8 is connected to ground (current). These are used for feedback on those it seems.

Both of these show approximately 150 mv when being probed. If it's a DC signal then it's not a very large one, though I suppose it could be overflow (from a negative voltage)

At all times, tube on/off, there is a potential difference between pins 6 and 12 (6 red wire) of 12 volts. So, power.

And at all times, between 6 and 13, there is a potential of 7.65-7.85 volts. Not sure about this one --- I would have though it would be the voltage setpoint but it's always on. Maybe the controller outputs that by default and the range is really like 5-24 volts or something. 

When x-rays are on ONLY, pin 11 is connected to pin 6, otherwise they are unconnected. So it is likely that connecting pin 11 to 6 will turn on the x-rays, while some other combination chooses current and voltage. 

And that's all I got for now.