REXGEN: live CAN with SavvyCAN

Use your REXGEN logger as a live CAN interface for SavvyCAN, a free CAN analysis tool. Watch the bus in real time, decode it with a DBC file and send your own frames. It works with REXGEN 1, REXGEN 2 and REXGEN 2 IMU GNSS.

Before you start

• Update the logger. The direct connection needs logger firmware 2.18 or later. See REXGEN: update the firmware and set the clock.
• Get SavvyCAN. Download the current Windows release from the SavvyCAN releases page on GitHub, extract the ZIP file and open SavvyCAN.exe. The SavvyCAN documentation covers every feature.
• Connect the logger. Plug it into the PC over USB and connect it to the CAN bus. The PC needs the REXGEN USB driver. See REXDESK: install the software and the REXGEN USB driver.

There are two ways to connect: directly over QT SerialBus, or through the J2534 driver. Use the direct route unless your logger's firmware is older than 2.18.

Connect directly over QT SerialBus

1. Open the connection window. On the Connection menu, select Open Connection Window.
2. Add a connection. Select Add New Device Connection.
3. Choose the REXGEN device. Set Connection Type to QT SerialBus Devices, SerialBus Device Type to ReXgen and Port to CAN 0 (or the channel you want). Select Create New Connection.

   

4. Set the bit rate. Select the new device in the list, choose the bus Speed and select Save Bus Settings.

   

5. Watch the trace. CAN frames start to appear in the main window.
6. Enable Overwrite Mode. In the main window, tick Overwrite Mode. It keeps SavvyCAN stable on a busy bus.

Connect through the J2534 driver

This route uses the REXGEN J2534 driver, so install it first. See REXGEN: use the logger as a J2534 pass-thru interface.

1. Add a connection. Open the connection window and select Add New Device Connection.
2. Choose the pass-thru device. Set Connection Type to QT SerialBus Devices, SerialBus Device Type to passthrucan and Port to Rexgen. Select Create New Connection.

   

3. Set the bit rate. Choose the Speed. A change of speed deselects the device. Select the device again, then select Save Bus Settings.
4. Watch the trace. When the connection is live, SavvyCAN starts collecting CAN messages.

Decode live data with a DBC file

1. Open the DBC manager. On the File menu, select DBC File Manager.
2. Load your DBC file. Select Load and open the file. Loaded files appear in the list. Close the window.
3. Decode the frames. In the main window, tick Interpret Frames and select Expand All Rows. Each frame now shows its decoded signals.

   

New to DBC files? Read understanding CAN DBC.

Send your own CAN frames

1. Open the frame sender. On the Send Frames menu, select Custom. The Frame Sender window opens.
2. Enter the message. Fill in one row per frame:
   • Bus: 0 or 1.
   • ID: the CAN identifier. Put 0x in front if you enter it in hexadecimal.
   • Len: the number of data bytes.
   • Data: the bytes, for example 0x02 0x01 0x0C.
   • Trigger: when to send it, for example every 100ms.
   • Modifications: advanced options. See the SavvyCAN documentation.
3. Start sending. Tick En on the row.

To record OBD-II parameters on the logger itself, without a PC, see REXGEN: log OBD2 Mode 1 PIDs.