HP 8712ET User Manual Supplement page 76

Controlling Peripherals
You can access the analyzer's rear panel interface ports from your
measurement control program. Using this capability, you can
communicate with peripherals such as material handlers, custom DUT
interface circuits, external switch boxes, and printers.
This chapter will focus on use of the Centronics parallel port and the
RS-232 serial port. Communication with the DIN KEYBOARD interface,
the USER TTL, and the LIMIT TEST TTL connectors is described in
detail in Chapter 3, "Operator Interaction."
Refer to your analyzer's User's Guide for pinout illustrations and
NOTE
descriptions of the parallel and serial ports.
6-2 Automating Measurements