IDEMIA DOCUMENT
– REPRODUCTION AND DISCLOSURE PROHIBITED
RS-485 Communication
12
IMPORTANT:
A maximum of 31 devices may be installed on the same line.
The maximum total cable length is 4000 ft. (1200m).
The cable must be dedicated to this installation and not used for any other purpose
St
ep
three
:
c
om
m
unic
at
ions
RS-232
from the
Com Port
RS-232 to
RS-485
converter
RS-485 to
1200m (4000ft)
For RS-485 installations, the cable should be run in a daisy-
chain configuration (i.e. converter > position 1 > position 2 >
position 3, etc.).
Use CAT-5 UTP (or better) cable (shielded recommended) with a characteristic impedance of 120 ohms.
AWG 24 should be the minimum wire gauge used.
Choose one twisted pair of conductors to use for RS485_TX_Y (TX+, Green / Black wire - 10) and RS485_TX_Z (TX-, Green
/ White wire - 8). Another conductor should be used for Signal Ground (Black / Red wire - 11).
Choose a RS-232 to RS-485 converter that supports Sense
Data to switch from Send to Receive mode.
IDEMIA - 2018_2000035854
– V1
8
RS485_TX_Z (-)
Green / White
10
RS485_TX_Y (+)
Green / Black
11
RS485_GND
Black / Red
