HP LaserJet 4050 Printer series - Manual (Page 200)

A-20 Specifications
EN
DB-9 Serial Cable Pin Outs (C2932A)
DB-25 Serial Cable Pin Outs (C2933A)
Note The pin outs for the computer end are typical pin numbers. The
actual pin numbers for your computer may be different. Check the
documentation for your computer to verify the proper pin outs.
Pins not shown are not used by the printer.
Computer DB-9 Printer DB-9 (male cable end)
2- Receive Data 2- Transmit Data
3- Transmit Data 3- Receive Data
4- Data Terminal Ready 4- Data Set Ready
5- Ground 5- Ground
6- Data Set Ready 6- Data Terminal Ready
8- Clear to Send 8- Data Terminal Ready
Computer DB-25 Printer DB-9 (male cable end)
3- Receive Data 2- Transmit Data
2- Transmit Data 3- Receive Data
20- Data Terminal Ready 4- Data Set Ready
7- Ground 5- Ground
6- Data Set Ready 6- Data Terminal Ready
5- Clear to Send 8- Data Terminal Ready