B
ioEntry Smart/Pass BioEntry Installation Guide 14
Copyright © 2005 by Suprema Inc. http://www.supremainc.com
At each end of the network, termination resistors of 120ohms should be
connected between ‘+’ and ‘-’ signals for proper impedance matching.
BioEntry
TX+
TX-
RX +
RX-
BioEntry
TX+
TX-
RX +
RX-
BioEntry
TX+
TX-
RX +
RX-
RS-485
Converter
T
X
-
T
X
+
R
X
-
R
X
+
PC
RS-232
Termination
Resistor
Termination
Resistor
Connect cable
shield to earth
GND at one
point only
Figure 3> A half duplex BioEntry network
Warnings: To prevent ground loops and avoid communication problems, connect cable
shield to earth GND at only one point.
2.5.4.
Connecting via auxiliary interface
The BioEntry series provide an auxiliary port to support connection to laptops,
even if the device is not networked during installation. The user can access and
manage the device with standard RS-232C port.
