Won't it make sense to add a field for the serial connector's voltage level to the "hwdata" template?
I want to add that detail to a device page and thought it might best be placed in data fields. Appending it to "Serial connection parameters:" doesn't seem right. Alternatively I'd just add it to the device page in text.
I have now added Serial connection voltage to the dataentry template.
Currently selectable values: 5, 3.3, 2.5, 1.8
Please let me know if more values are needed.
There are also some enterprise'ish devices (with real 9-pin DE-9 or Cisco style connectors) using RS-232C at +/- 15 volts (up to +/-25 volts allowed in open circuit operations). Examples would include Sophos/ Gateprotect UTMs on x86_64, some of the managed switches of the realtek target (most not exposing the DE-9 connector, but still having it onboard with level shifters to use +/- 15 volts), some enterprise APs (e.g. Meraki and friends, usually with a cisco style rj45 console port running at +/- 15 volts).