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Thursday, February 19, 2009

RS485 Convertor User Manual

Author: Chaonan Chen, Huihui Duan, Au Group Electronics
The RS485 Convertor (Part # CVT485 and CVT485E)is a handheld device typically used for converting RS485/SAE J1708 signal (two-wire operation balanced half-duplex) to a RS232 signal (two-channel) and vice verse. An external +12V power supply is required. It has a DB-9 female RS-232C connector and a DB-9 male/female connector on the RS485 bus side. The DB-9 male-connector and its cable on the RS485 side is the most popular choice.

Major Features:
• Dimension & Weight: 3.1" L x 1.69"W x 0.8"H (78 x 43 x 21 mm); 2.8 oz
• Color: PC white or Black
• Power supply: +12V, 35 mA normal, 350 mA max.
• PC interface: DB-9 female RS232C connector
• RS485/SAE J1708 connector: DB-9 male(most popular)/female connector (Note: pin functions are different between male and female connectors)
• Data rate: 115.2K baud rate (with echo) max.
• Temperature range: 0 ~ 70 °C (CVT485), -40°C ~ 85 °C (CVT485E)
• Completely Auto-Sensing and Self-Adjusting (Baud Rates and Data Formats).


A RS485 convertor is illustrated in figure 1.

There is 1 LED power indicator on top view, and it will be on when the device is connected to +12V power supply. RS232 connector pin-out is shown in figure 2. RS485/SAE J1708 female/male connectors are shown in figure 3 and Table 1.

For male RS485/SAE J1708 interface (most popular), position 1 is ground (GND), position 5 is +12V power supply, position 8 is Data A (-) / J1708-, position 9 is Data B (+)/J1708+, and all other positions are not connected (NC).
For female RS485/SAE J1708 interface, position 1 is +12V power supply, position 5 is ground (GND), position 6 is Data B (+)/J1708+, and position 7 is Data A (-) / J1708-, all other positions are not connected (NC).

Step by Step operation:

1. Use serial cable (AU part#: CBL-RS232-01) to connect “RS485 Convertor” RS232 side to PC serial port.
2. Use RS485 cable (AU part#: CBL-RS485-01 for male connector (most popular); AU part #: CBL-RS485-02 for female connector) to connect “RS485 Convertor” RS485 side to RS485/SAE J1708 network.
3. PC to RS485/SAE J1708 network connection is set up.

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