485CARLP9A4300 - pg. 1/1
Carrier HVAC Converter
Includes Send Data Control
Model 485CARLP9A
CE
The Model 485CARLP9A is an RS-232 to RS-485 converter that allows you to connect your
laptop PC to Carrier HVAC equipment.
The 485CARLP9A is a port-powered, half-duplex RS-232 to RS-485 converter with send data
control. The unit converts TD and RD RS-232 lines to balanced RS-485 signals and supports three-wire (Data A, B, and Signal Ground
reference) RS-485 communications only. The converter is powered from the RS-232 handshake lines, RTS, CTS and DTR, DSR, CD. The
handshake lines are looped back on each other and can be in either state. No handshake change is necessary so no software is required to
control the lines. The RS-485 driver is enabled with each bit of data. The RS-485 receiver is disabled when the driver is enabled and is
enabled when the driver is disabled. This prevents data from being echoed back into the RS-232 device. The RS-232 side has a DB-9 female
connector. The RS-485 side has a six-position RJ11 connector.
NOTE: This converter is not optically isolated.
Connections
Regardless of the system, the 485CARLP9A must be connected with the proper polarity (See Table 1). With no data being sent and the
driver enabled, the RS-232 line should be negative and the Data(A) should be negative with respect to Data(B).
Proper operation of any RS-485 system requires the presence of a signal return path between the signal grounds of the equipment at
each end of an interconnection. This circuit reference may be established by a third conductor connecting the common leads of devices, or it
may be provided by connections in each equipment to an earth reference. When the circuit reference is provided by a third conductor, the
connection between the signal grounds and the third conductor should contain some resistance (e.g. 100 ohms) to limit circulating currents
when other ground connections are provided for safety.
DECLARATION OF CONFORMITY
Manufacturer’s Name:
Manufacturer’s Address:
B&B Electronics Manufacturing Company
P.O. Box 1040
707 Dayton Road
Ottawa, IL 61350 USA
485CARLP9A
RS-232 to Rs-485 Data Converter with
Send Data Control, Port-powered, DB9 to RJ45
Type:
Application of Council
Directive:
89/336/EEC
EN 50082-1 (IEC 801-2, IEC 801-3, IEC 801-4)
EN 50081-1 (EN 55022, IEC 1000-4-2)
EN 61000 (-4-2, -4-3, -4-4, -4-5, -4-6, -4-8, -4-11)
ENV 50204
EN 55024
Light industrial ITE equipment
Model Number:
Description:
Table 1: 485CARLP9A Pin-Outs
Signal
Data A (-)
Data B (+)
Signal Ground
Specifications
Communication:
Data Rate:
Power:
Dimensions:
Temperature Range:
RJ11 Pin #
2
5
4
Standards:
Michael J. Fahrion, Director of Engineering
Two-wire with Signal Ground reference
115.2K Baud max.
Port-powered from handshake lines
3.0 x 1.3 x 0.9 in
0°C to 70°C
RS-485
© B&B Electronics – Revised November 2000
This product designed and manufactured in USA of domestic and imported parts by
stm32/stm8
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