NVITE | installation guide
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3.2
Communication
3.2.1
RS485
The NVITE reader has a RS485 interface for communication with a host system or to configure the reader settings.
RS485 is a 2-wire half-duplex serial communication interface using balanced lines.
STANDARD and OSDP protocol are available.
Connections
BROWN
RS485 A (-)
Balanced RX/TX
GREEN
RS485 B (+)
Balanced RX/TR
SHIELD
Shield connected to DC-ground
For details about reader configuration see chapter 4.
STANDARD firmware
This is the default NVITE reader firmware version and implements a simple CR/LF protocol.
The RS485 output message format is described in chapter 4.5.1.
Default baud rate is 115200. See chapter 4.2.4 for details about baud rate setup.
OSDP firmware
The NVITE reader has implemented the OSDP protocol including the Secure Channel Protocol.
Default baud rate is 9600. This may be changed using the OSDP_COMSET command.
Perform a firmware update to change from STANDARD to OSDP (or vice versa).
The firmware update procedure is described in chapter 4.6.1.
RS485 point-to-point communication
Termination resistors (120
Ω
) are recommended to prevent unwanted signal reflections on long RS485 communication
lines. The resistors should be installed at both ends of the communication line.
Figure 3: RS485 point-to-point communication
Notes
•
Use shielded twisted pair cable when extending the RS485 wiring beyond the standard 5 meter cable.
•
Maximum RS485 cable length 1200 meters (
6000 feet
).
•
The RS485 interface is disabled while the USB interface is in use.
HOST
A
B
120
Ω
120
Ω
NVITE
A
B
