Astromech socket wiring standards, revised
Rev. 4 changes the permission layer, the ejection interlock and one connector pinout. If you are running Rev. 3 cable, read the last section.
The Droid Interface Standard moved to Rev. 4 this quarter. Most of the changes are clarifications, but three are substantive and one will bite anyone running older cable.
Change 1: the permission layer is now mandatory
Rev. 3 described a permission layer for droid access to the systems bus and made it optional. In practice this meant most installations gave the droid unrestricted read/write access to everything, because that was the default and it worked.
It worked until an astromech with a corrupted task queue re-routed power away from life support on a survey vessel, correctly, according to instructions it had been given nine days earlier by a technician who had since left the ship. Nobody was hurt. It was close.
Rev. 4 makes the permission layer mandatory and specifies four access tiers:
| Tier | Access | Typical use |
|---|---|---|
| 0 | Read-only, non-critical | Passenger hulls |
| 1 | Read all, write non-critical | Freight, standard |
| 2 | Read all, write with crew confirm | Survey, long range |
| 3 | Full autonomous write | Unmanned only |
Tier 3 on a crewed hull is now a certification failure. The AS-3 ships defaulted to Tier 1.
Change 2: droid-initiated ejection is standardised
Rev. 3 allowed droid-initiated ejection but did not specify the signalling. Three manufacturers implemented it three ways. Rev. 4 specifies a single two-wire interlock with a defined failure state — loss of signal means do not eject, which is the correct default and, notably, not what one of the three implementations did.
Change 3: the pinout
Pins 7 and 9 on the primary connector have swapped function. Pin 7 is now the permission-layer handshake; pin 9 carries the ejection interlock.
This is the change that will bite you. Rev. 3 cable physically mates with a Rev. 4 socket. It will present a droid that appears to enumerate correctly, sits at the wrong access tier, and has a non-functioning ejection interlock — a socket that looks fine on every panel readout and is not.
What to do if you are on Rev. 3 cable
Check the harness stamp behind the retention collar. If it does not read DIS-4 or later,
replace the harness before your next droid rotation. It is a two-hour job and about ninety
credits of cable. The alternative is a droid bay whose safety interlock is decorative.
We are supplying Rev. 4 harnesses at cost through the end of the year. Contact field service with your socket serial and we will ship one.