Can bus monitoring tool based on arduino and can bus shield. Implements CAN ASCII/SLCAN protocol compatible with Lawicel CAN232/CANUSB. Can be used for monitoring low speed CAN (interior can bus of most cars, less than 500kbps). For higher speeds serial port can become a bottleneck in case data density is high.
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CAN BUS monitoring software based on Arduino with Seeduino/ElecFreaks CAN BUS shield based on MCP2515 (Numerous other MCP2515 based CAN BUS modules from ebay and aliexpress work well to).

This software implements CAN ASCII / Serial CAN / SLCAN protocol compatible with Lawicel CAN232/CANUSB.

As for PC counterpart software I personally used and can recommend two tools:

  1. [Windows] CANHacker tool v.2.00.01 (by fuchs) to sniff and visualize data on the bus. You can download CANHacker tool from this forum page:

  2. [Windows] CAN-COOL (by MHS Elektronik), open source, but unfortunaly available only in German. Download link: (Make sure you select RS232 and SL-CAN protocol and then click hardware bus reset icon on a toolbar)

  3. [Linux] Please dig into direction of SLCAN/SocketCAN, but start from

This monitor uses CAN BUS library forked from

Copyright (C) 2015,2016 Anton Viktorov

You can buy me a beer if you like the tool :o) Donate

See protocol definition here and here

Commands not supported/not implemented:

  • s, W, M, m, U.

Commands modified:

  • S - supports not declared 83.3 rate
  • F - returns MCP2515 error flags
  • Z - extra Z2 option enables 4 byte timestamp vs standard 2 byte (60000ms max)
'S' |   YES+      |   Sn[CR]               Setup with standard CAN bit-rates where n is 0-8.
    |             |                        S0 10Kbit          S4 125Kbit         S8 1Mbit
    |             |                        S1 20Kbit          S5 250Kbit         S9 83.3Kbit
    |             |                        S2 50Kbit          S6 500Kbit
    |             |                        S3 100Kbit         S7 800Kbit
's' |    -        |   sxxyy[CR]            Setup with BTR0/BTR1 CAN bit-rates where xx and yy is a hex value.
'O' |   YES       |   O[CR]                Open the CAN channel in normal mode (sending & receiving).
'L' |   YES       |   L[CR]                Open the CAN channel in listen only mode (receiving).
'C' |   YES       |   C[CR]                Close the CAN channel.
't' |   YES       |   tiiildd...[CR]       Transmit a standard (11bit) CAN frame.
'T' |   YES       |   Tiiiiiiiildd...[CR]  Transmit an extended (29bit) CAN frame
'r' |   YES       |   riiil[CR]            Transmit an standard RTR (11bit) CAN frame.
'R' |   YES       |   Riiiiiiiil[CR]       Transmit an extended RTR (29bit) CAN frame.
'P' |   YES       |   P[CR]                Poll incomming FIFO for CAN frames (single poll)
'A' |   YES       |   A[CR]                Polls incomming FIFO for CAN frames (all pending frames)
'F' |   YES+      |   F[CR]                Read Status Flags.
'X' |   YES       |   Xn[CR]               Sets Auto Poll/Send ON/OFF for received frames.
'W' |    -        |   Wn[CR]               Filter mode setting. By default CAN232 works in dual filter mode (0) and is backwards compatible with previous CAN232 versions.
'M' |    -        |   Mxxxxxxxx[CR]        Sets Acceptance Code Register (ACn Register of SJA1000). // we use MCP2515, not supported
'm' |    -        |   mxxxxxxxx[CR]        Sets Acceptance Mask Register (AMn Register of SJA1000). // we use MCP2515, not supported
'U' |   YES       |   Un[CR]               Setup UART with a new baud rate where n is 0-6.
'V' |   YES       |   v[CR]                Get Version number of both CAN232 hardware and software
'v' |   YES       |   V[CR]                Get Version number of both CAN232 hardware and software
'N' |   YES       |   N[CR]                Get Serial number of the CAN232.
'Z' |   YES+      |   Zn[CR]               Sets Time Stamp ON/OFF for received frames only. EXTENSION to LAWICEL: Z2 - millis() timestamp w/o standard 60000ms cycle
'Q' |   YES  todo |       Qn[CR]               Auto Startup feature (from power on).