Q-See QX628 Technical Manual

The RS458 communication use half-duplexes communication, there

are no more than 32 QS series fingerprint attendance devices in an
attendance network.

The device RS485 connector is a RJ11 plug port; RJ11 plug port

front illustration and signal definition are following:

Some RS232/485 transducer have four label TX+, TX-, RX+, RX-
connector terminal, there are only two connector terminals in .the
equipment, because we join the TX+ and TX-signal, RX+ and TX-signal,
while we connect with this transducer, it is necessary to join TX+ and
RX+ terminal which connect RS485+, and to join TX- and RX- terminal
which connnect RS485-, so that communication is successful.

RS 232/485
transducer

RS485+

RS485-

RS485+ RS485-

Number 1

RS485+ RS485-

Number N

1 2 3 4

RS485-

RS485+