CDBUS Bridge

The CDBUS Bridge HS is a USB-to-RS485 (CDBUS) adapter. The USB port supports High-Speed, and the RS485 interface supports up to 50 Mbps.

• The two RS485 ports are internally straight-through, simplifying wiring.

Switchs Defination：

• S1.1: Force bootloader mode.
• S1.2: In arbitration mode, the maximum limit of baud_l:
  OFF: Default 1 Mbps; ON: Default 2 Mbps. (modifiable)
• S2.1: Enable pull-up resistor.
• S2.2: Enable termination resistor.
• S2.3: Enable pull-down resistor.
• S2.4 (HW v6.2+): When enabled together with S2.3, pulls B to 1.65V, allowing signal A to operate as a TTL single-wire serial.
• S2.5 (HW v6.2+) / S2.4: Enable 5V output (should disable when using external power supply).

Transparent Mode

• The PC sends complete CDBUS packets (with CRC) via USB serial to the CDBUS Bridge, which forwards them unchanged to the RS-485 bus.
• Data received from RS-485 is sent unchanged back to the PC via USB serial.
• The baud rate set by the PC when opening the USB serial port is used for RS-485 (baud_l is automatically limited in arbitration mode).
• The PC must enable the DTR option on the USB serial port.
• The default RS-485 address of the Bridge is 0. To change it, see the next section.
• Raw mode allows arbitrary data transfer without following the CDBUS byte format (HW v6.2+).

Configuration Mode

CDBUS GUI Tool: https://github.com/dukelec/cdbus_gui

When you open the serial port, specify the baud rate as 52685 (0xcdcd) to enter the configuration mode.

The target address should be set to 00:00:ff.

After modifying the configuration, write 1 to save_conf to save the changes to flash.

To restore the default configuration, change the value of magic_code to a different value, save it to flash, and then power cycle the device.

Download Source Code

git clone --recursive https://github.com/dukelec/cdbus_bridge

For other hardware versions, please switch to the corresponding branch.

Test

git clone --recursive https://github.com/dukelec/cdbus_tools

cd cdbus_tools/
./cdbus_terminal.py --help

We can also use a generic serial debugging tool for loopback testing. For example, to simulate node 02 sending a packet to node 00 (with CRC):

02 00 01  cd  c1 99

If the hardware works properly, the same packet should be received.