Datamax Prodigy Plus Operator's Manual page 103

When a serial (RS-232C) interface between the Printer and the host will
be used, a serial interface cable is needed to connect the Printer to the
host. Cable configurations for typical interfaces are shown below,
(Contact your reseller for part numbers and ordering information).
Null Modem (MXM) "PC" (DB25P) to Printer
"PC" (DB9P) to Printer RS-422 Connection
Table 2-1 Interface Cable Applications
Other applications may require a parallel connection from the Printer to
the host. The Printer can be connected to the host with a standard parallel
printer cable if the Printer is equipped with the optional parallel interface
option.
Prodigy Max Operator's Manual 13