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R S 4 8 5
The RS-485 interface uses a Differential Data Transmission that can help nullify the effects of ground shifts
and induced noise signals that can appear as common mode voltages on a network.
The CL4490 implements a RS-485 (2-wire Half Duplex) multi-drop interface. Typically, a RS-485 bus will
consist of a master and several slaves. The nodes will have unique addresses and can send addressed
packets to specific nodes. Because the bus is half duplex, no two nodes should try to talk at the same time.
The CL4490 does not have a RS-485 address, therefore, it will transmit all RS-485 traffic over the RF.
Conversely, as soon as a CL4490 receives a packet over the RF, it will transmit the packet over the RS-485
bus.
T A B L E 4 : C L 4 4 9 0 T E R M I N A L B L O C K P I N O U T
1
Note: When using RS485 (2-wire Half Duplex), a RS485 to RS232 converter is required to configure the
unit.
RS232-485 Converter
DESIGN TIP
Many simple 2 or 4-wire converters do not provide hardware flow control capabilities and
therefore require Handshaking to be disabled in the Aerocomm Configuration Utility to
configure the radio. Check with your converter Manufacturer for any specific requirements.
C H A P T E R 3 - S E R I A L I N T E R F A C E
T E R M I N A L
S I G N A L N A M E
B L O C K P I N
1
VCC
2
485 -
6
3
N/C
4
N/C
5
485 +
6
GND
F i g u r e 9 : R S 2 3 2 - 4 8 5 C o n v e r t e r
+5V
GND
B-
A+
D E S C R I P T I O N
6-18V (1.3A required)
485B
No Connect
No Connect
485A
Ground
CL4490-1000-485
Terminal Block
Power Connector
1
6
485 -
485 +
w w w . a e r o c o m m . c o m
7
1 - 8 0 0 - 4 9 2 - 2 3 2 0
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