BUSMASTER transmit test patterns and message send count

BUSMASTER 3.2.2.47 and later can vary the CAN or LIN identifier, a selected payload bit field, or both from the Transmit Window. Send Count can also limit how many times one row is transmitted. Test Pattern, Send Count, and Repetition are independent, so each can be used alone or in combination.

In short, Test Pattern controls how the ID or payload changes on each transmission, Send Count controls the total number of periodic transmissions in the run, and Repetition (ms) controls the interval.

1. Create a transmit row

1. Open CAN -> Transmit Window; use LIN -> Transmit Window for a LIN project.
2. Double-click [Add Message] and select a database message, or enter the ID, channel, length, and type for a non-database message.
3. Verify that the fixed frame transmits correctly before enabling Test Pattern.

This example combines a pattern with Send Count = 10 and Repetition = 1000 ms:

2. Select a pattern

Test Pattern provides these choices:

Pattern	Change on each periodic transmission
Disabled	Keep the current ID and payload
ID Increment	Add the configured step and wrap after the maximum ID
ID Random	Choose an ID between the configured minimum and maximum
Data Increment	Increment the selected payload field and wrap after its maximum
Data Random	Choose a value between the selected field’s minimum and maximum
Four ID ... + Data ... choices	Run the ID and data generators together with independent state

3. Configure ID and payload parameters

Selecting the row displays the parameters required by its pattern.

ID parameters

• ID Min is the first ID in a run.
• ID Max is the highest allowed ID.
• Step value is added by an incrementing pattern; random patterns do not use it.

For example, an ID range of 0x100–0x10F with step 1 advances from 0x100 to 0x10F, then wraps to 0x100.

Data parameters

• Data Min / Data Max define the selected field’s value range.
• Step value is added by an incrementing pattern.
• Start bit locates the field.
• Bit width can be 1 through 64 bits.
• Byte order selects Intel or Motorola.

For example, Start bit = 8, Bit width = 16, Intel, range 0–255, and step 1 changes only that 16-bit field. All other payload bits continue to use the row’s current template. The field must fit inside the current DLC and the configured values must fit its width.

4. Set the message send count (Send Count)

1. Enter a period in Repetition (ms) and check the column.
2. Use Infinite for continuous transmission.
3. Enter 1–65534 for a finite run. Common presets include 10, 100, 1000, and 10000.

BUSMASTER counts successful periodic submissions only. When a finite run completes, it stops the row and clears Repetition. Checking it again starts a new run with the complete count. A manual Send Message action or keyboard-triggered frame does not consume the periodic count.

Test Pattern and Send Count remain independent:

• Pattern only: repeat the generated range until manually stopped.
• Count only: send the fixed ID and payload N times.
• Pattern and count: advance the generator on each period and stop after the Nth successful periodic submission.

For example, if the ID range is 0x100–0x1FF but Send Count = 10, the run sends only its first 10 generated IDs. If the pattern range ends first, it wraps according to its own rules until the count reaches N.

5. CAN and LIN boundaries

• CAN/CAN FD validates the ID against the selected standard or extended frame format. RTR frames have no payload and cannot use a Data pattern.
• LIN patterns are available for independently timed Master Write rows. A Master Read row can use a finite count but does not generate payload data.
• A LIN Slave Response is triggered by an external master and does not use a finite periodic count or test pattern.
• A row owned by a LIN Schedule Table uses schedule timing and an Infinite standalone count. Stop the schedule before editing standalone timing.

6. Verification and safety

• Begin with a slow period and use an independent receiver to verify ID, channel, DLC, payload order, and physical frame count.
• Motorola and Intel start-bit conventions differ. If unsure, use a small range and inspect the actual byte changes first.
• Editing valid pattern parameters while a row is running safely restarts that row from its configured minimum; other rows keep their state.
• After changing DLC, frame type, or RTR, correct any field that no longer fits before re-enabling repetition.
• A sweep or random pattern can produce traffic an ECU does not expect. Use an authorized test network, not a live vehicle or safety-critical bus.

Quick example

To send 10 frames with both an incrementing ID and payload field:

1. Select ID Increment + Data Increment.
2. Set the ID Min, Max, and Step.
3. Set the Data Min, Max, Step, Start bit, Bit width, and Byte order.
4. Set Send Count = 10.
5. Enter the period and check Repetition.
6. Verify that an independent receiver sees 10 frames and then no more. Check Repetition again for the next run.

Frequently asked questions

How can BUSMASTER transmit a message only a specified number of times?

Set Send Count to a value from 1–65534, enter Repetition (ms), and enable periodic transmission. BUSMASTER stops the row and clears Repetition when the count is reached. To repeat a fixed frame N times, leave Test Pattern = Disabled.

Must a test pattern be used together with Send Count?

No. The two controls are independent. You can run a pattern continuously, transmit a fixed frame N times, or advance the pattern and stop after the Nth successful periodic transmission.

Why does checking Repetition again restart the full count?

After a finite run completes, is stopped manually, or is disconnected, checking Repetition starts a new run. Send Count restarts from its configured value, and an incrementing pattern restarts from its configured minimum.

Does Send Message consume the periodic send count?

No. Send Count counts successful periodic submissions only. A manual Send Message action or keyboard-triggered frame does not consume the run count.

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Source: BUSMUST technical knowledge base transmit-test-patterns.md. This public guide is maintained by the website content pipeline. Use the download center for current and archived software releases.