12
RS-232 TO RS-485 INTERFACE CONVERTER W/OPTO ISOLATION
KEY TO TABLE 3-2
†S1-1, S1-2, and S1-4: only one switch can be ON at any time. The other
two must be OFF. We recommend that you disconnect the Converter while
changing configurations.
*JP4A: If this jumper is off, only the RS-485 transmitter is controlled by
RTS or DTR. If this jumper is ON, both the RS-485 transmitter and receiver
are controller by RTS or DTR. When the transmitter is OFF, the receiver will
be ON, and similarly, when the transmitter is ON, the receiver is OFF.
**JP3A and JP3B: Both jumpers are either ON or OFF. When the jumpers
are ON, the RS-485 transmitter and receiver are connected directly
together. This will only function in half-duplex mode. When both jumpers
are OFF, the RS-485 transmitter and receiver are disconnected from each
other. The Converter can operate in either half- or full-duplex, depending on
the setting of JP4A.
S
WITCH
S1: RTS C
ONTROL
When Switch S1 is in the ON position, the DTE input
signal RTS (Pin 4) controls the transmitter of the
Converter. In this mode, when RTS is high, the
Converter transmits data from the RS-232 port to the
RS-485 port. Switch S2 and S4 must be in the OFF
position when Switch S1 is ON.
S1
Setting
ON
RTS controls the transmitter
OFF
RTS control is OFF
