Black Box IC107A-R3 - Manual (Page 17)

16
RS-232
↔RS-422/485 CONVERTER (DATA ONLY)
Table A-2. Pinning of the RS-422/485 connector
(4-position terminal block).
Pin/Signal Function
TXA and TXB Data received by the Converter from the RS-232 port is
transmitted out of the unit over twisted-pair wires using
these two outputs. The “TX” LED indicates the state of these
two leads. When the TXA lead is positive with respect to the
TXB lead (a zero is being transmitted), the “TX” LED is lit.
RXA and RXB These are the received data inputs for the RS-422/485 port.
The status of these leads is monitored by the “RX” LED.
When the RXA lead is positive with respect to the RXB lead
(a zero is being received), the “RX” LED is lit.