DB9
DE-9 Serial (RS-232)
Invented in
1969
Invented by
The EIA RS-232 committee
Availability
Niche / industrial
The 9-pin D-sub serial port that connected mice, modems and industrial gear for decades. Still alive today wherever machines, sensors and controllers need a simple, robust link.
Technical specifications
Introduced1969 (RS-232)
SignalSerial data
ConnectorDE-9 D-sub
FixingTwo thumbscrews
Recommended brands
01StarTech
02Lindy
03DeLOCK
Where to buy
Europe-focused retailer searches. Some links are affiliate links and may earn a commission.
Common adapters and cables
Fun fact
Officially it is "DE-9", but almost everyone calls it DB9, a naming mix-up that has stuck for over fifty years.
Tips & tricks
Null-modem vs straight-through wiring matters, the wrong one means no communication.
Philosophy
Long dead on home PCs, very much alive in factories and labs. RS-232 simply refuses to retire.
Applications
Data
