REXDESK: transmit periodic CAN messages and HW info

Use a REXGEN as a CAN transmitter. Send messages on a fixed period and stamp them with the time. Another tool on the bus can also ask the logger for its firmware, configuration, serial number and clock.

What the logger can send

The Transmitting group of the Tools panel holds three tools. You drop all three on the Output area of the configuration:

• Periodic sends CAN and CAN FD messages on a fixed period.
• HW Info answers requests for hardware information.
• Snapshot sends decoded samples to the cloud. See REXDESK: send decoded snapshot files to S3.

Periodic transmission

1. Create a project. Select New Project on the toolbar.
2. Drop Periodic on Output. Drag Periodic from the Transmitting group onto the Output area. The Periodic messages window opens.
3. Set the bus. If the bus is not set up for logging already, select its Bus icon and set the type and bit rate. Bit Timing is there for advanced configurations.
4. Add the messages. Select Add for each message and fill in its row. The columns are described below.
5. Run the configuration. Select Run, then save and name the project. The configuration loads and the logger starts at once.

The toolbar of the window:

Add, Remove

Adds a message, or deletes the selected one.

Link Message Up, Unlink

Links one or more messages to the message above, or breaks the link.

Move Up, Move Down

Moves an unlinked message up or down the list.

Load

Load CSV reads the messages from a CSV file. Load From Cloud reads them from the cloud.

Save CSV

Saves the messages as a CSV file.

The columns of each message are below. Some builds label Ident as Tx Ident.

Ident

The message identifier.

Linked

Shows whether the message is linked to the one above.

Period

How often the message is sent.

Delay

The delay before the message is sent.

CAN 0 to CAN 3

The bus or buses the message goes out on.

Type

CAN Standard, CAN Extended, CAN FD Standard or CAN FD Extended.

BRS

Bit rate switch, for CAN FD messages.

Log Tx

Also records the sent messages in the log on the logger.

DLC

The number of data bytes, from 0 to 8. CAN FD also allows 12, 16, 20, 24, 32, 48 or 64.

Data

The data bytes.

Add a timestamp or the clock to a message

The button at the end of a row opens Link signals to the selected message. Select +, then select TimeStamp or RTC under Signal. Set its Start Bit and Bit Count in the message, then select OK.

Periodic transmission is also how a REXGEN requests OBD-II data. See REXGEN: log OBD2 Mode 1 PIDs.

Watch: Set up periodic message transmission in REXGEN (1:03)

HW info

With HW Info in the configuration, another tool on the bus can send the logger a CAN request and get back:

• The firmware version
• The configuration version, which confirms the logger is configured and the configuration is active
• The manufacturing information, including the serial number
• The date and time of the logger's clock

Drag HW Info onto the Output area and set it up:

Output CAN

CAN 0 or CAN 1.

Rx Ident

The first identifier the logger listens on for requests from the external tool.

Tx Ident

The first identifier the logger answers on.

Each kind of information has its own pair of identifiers, counting up from those two. With Rx Ident 7E0 and Tx Ident 7E8:

FW_TYPE

0 release, 1 alpha, 2 beta, 3 pre-release.

FW_BRANCH

0 main branch.

Next: REXDESK: sleep and wake settings.