Epson 3260 - Manual (Page 93)

Note:
The column heading "Direction" refers to the direction of signal flow as
viewed from the printer.
"Return" denotes the twisted-pair return, to be connected at signal ground
level. For the interface wiring, be sure to use a twisted-pair cable for each
signal and to complete the connection on the return side.
All interface conditions are based on the TTL level. Both the rise and fall
times of each signal must be less than 0.2 u.s.
Data transfer must be carried out by observing the ACKNLG or BUSY
signal. Data transfer to this printer can be carried out only after receipt of
the ACKNLG signal or when the BUSY signal is LOW.
Appendix A-11