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3. Reporting Mechanism

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NAKANISHI Kiyomaro edited this page May 7, 2025 · 10 revisions

General mechanism

This repository supports the reporting of transmitted frames in addition to notifications of received frames similar to CAN232 and CANUSB.

Rx frame reporting

When the device receives a CAN frame, it is notified in the same format as the transmission command: r, R, t, T, d, D, b and B. This function is enabled by default and can be disabled by z command. If disabled, the device will not send any data to the host even if it receives CAN frames.

The Rx frame reporting is summarized in the table bellow. See the "Contents in a report" section for the details of <Rx frame>.

Rx frame reporting Timing Message
Disabled Receive a frame -
Enabled Receive a frame <Rx frame>

Note:

  • Rx frames are subject to the acceptance filter. A Rx frame will not be reported if it's not accepted by the filter. See the "Acceptance filter" page for details.

Example:

  • t10020011[CR]

This message will be sent from the device when a classical CAN data frame with ID = 0x100 and 2 data bytes with the valued 0x00 and 0x11 is received.

Tx event reporting

When the device transmits a CAN frame and it's acknowledged by another node, it is notified in a format that is the transmission command plus a z or Z at the beginning. This function is disabled by default and can be enabled by z command. If disabled, the device responds with z[CR] or Z[CR] when the transmission command is in the correct format and successfully saved in the buffer without any reporting for a successful transmission.

The Tx event reporting is summarized in the table bellow. See the "Contents in a report" section for the details of <Tx event>.

Tx event reporting Timing Message
Disabled Save the Tx frame in the buffer z[CR] or Z[CR]
Disabled Discard the transmission command [BELL]
Disabled Successfully transmit the Tx frame -
Enabled Save the Tx frame in the buffer [CR]
Enabled Discard the transmission command [BELL]
Enabled Successfully transmit the Tx frame <Tx event>

Note:

  • If Tx event reporting is enabled and the frame transmission fails, the device will repeatedly attempt to send the frame until it is acknowledged, and then report the successful transmission.

Example:

  • zt10020011[CR]

This message will be sent from the device when a classical CAN data frame with ID = 0x100 and 2 data bytes with the valued 0x00 and 0x11 is transmitted.

Contents in a report

The <Rx frame> and <Tx event> always contain the type of frame, CAN ID, DLC and Data bytes (for data frames). The following items can be added to them:

  • Timestamp : Milli/micro second timestamp in hex, configurable with Z or z commands.
  • Error state indicator : ESI flag (0: Error active, 1: Error passive), configurable with z commands.

Format:

  • <z>riiil<tt...><e>[CR] (Base remote frame)
  • <Z>Riiiiiiiil<tt...><e>[CR] (Extended remote frame)
  • <z>xiiildd...<tt...><e>[CR] (Base data frame)
  • <Z>Xiiiiiiiildd...<tt...><e>[CR] (Extended data frame)

Where <z> or <Z> is used for <Tx event>, x = t / d / b, X = T / D / B, <tt...> is timestamp and <e> is ESI.

Example 1:

  • t10020011000A0[CR]

Denotes an incoming classical CAN data frame with ID = 0x100 and 2 data bytes with the valued 0x00 and 0x11. Additionally, milli second time stamp is activated and is 10 ms and ESI is 0 = error active.

Example 2:

  • zr20030000000F[CR]

Denotes a successful transmission of classical CAN remote frame with ID = 0x200 and DLC = 3. Additionally, micro second time stamp is activated and is 15 us.

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