Epson PP 803 - Serial Interface with

Appendix A System Interface Description
A-7
1.2.3 Serial Interface with RS-422
This interface typ requires the signal lines.
$ Pin 1 Protective Ground (PG)
$ 3 Receive Data (RDA)
$ 9 Send Data (SDA)
$ 10 Not Send Data (SDB)
$ 18 Not Receive Data (RDB)
Standard Connection
Note:
Protective ground (PG) connected either to host
or
printer