Tektronix 070-8811-08 - Manual (Page 78)

Reference
764 Digital Audio Monitor User Manual 63
NOTE. RS-232 signals are named from the perspective of the DTE
device. Since the 764 is a DCE device, pin 2 (Received Data) is an
output from the instrument; that is, the data is received by the
connected DTE device.
The 764 supports both hardware (RTS/CTS) and software (Xon/Xoff)
handshaking; choose the appropriate handshaking protocol through
the Serial Port submenu. Set the serial communication parameters of
the connected device to 8 bits, 1 stop bit, and no parity. Be sure that
the same Baud rate is selected at the 764 and the connected device.
Figure 35: Connecting to a DTE device with a DB25 serial port