Epson C824431 Mode D'emploi page 15

Jumper settings
Table 6. shows information about the interface conditions
that can be selected using jumpers. In all cases, ON denotes
the connection of the jumper (covering both terminals),
while OFF denotes the disconnection of the jumper.
Table 6. Jumper settings
Jumper
ON: Pulls up "TTY-TXD" to +5v via
J1
JNOR Flag polarity selection for Current loop.
J2
JREV
ON: X-ON/X-OFF can be transmitted from
J3
OFF: Set TXD to SPACE.
Note
If the host computer is not equipped with a power supply
for the Current Loop interface, set jumper J1 to ON and also
connect "TTY -TXD Return" to Signal Ground (pin No.7) of
the interface card.
Function
200 ohms resistance.
TXD (pin No.2).
11
Factory
setting
OFF
(See note)
(See Table 7.)
OFF
ON
ON