Line utilization and transport statistics

Transport statistics show line utilization, traffic rates and, when an applicable reference is known, CAN adapter load. They complement Monitor, which shows the latest values and individual message periods, and Tracer, which retains the message sequence.

Opening the panel

1. Connect to a line carrying traffic.
2. Hover over or click the transport name in the main window's status bar. A compact summary opens with measurements and a graph of the last minute.
3. Click Expand traffic analysis in the summary's upper-right corner. A panel with load history and traffic composition opens at the bottom of the workspace.

Statistics collection continues while the panel is closed and when switching between Tracer and Monitor. Tracer table filters do not reduce the displayed load.

Reading the measurements

Indicator	Meaning
Percentage beside the transport name	Current line utilization; always CAN bus load for CAN connections
Cur / Last	The connected source's current value, even while viewing a past range
Max	Highest utilization among measurement intervals
Avg / AVG	Average utilization weighted by interval duration
≈	A calculated estimate, not an exact hardware measurement
↓ / ↑	Received / transmitted payload rate when a utilization percentage is unsupported
Errors / Dropped	Errors / losses reported by the transport; shown when counters are nonzero

In the compact summary, Max and Avg cover the current connection since observation began. In the expanded panel, they cover the visible graph range or the selected interval. Last in the expanded legend replaces Cur and retains its meaning: the current source value, even while viewing history.

Measurements update approximately once a second. Max is therefore the maximum of those interval measurements: a brief burst within a second may be higher. For line utilization, ≈25 % means estimated transmission occupied about a quarter of the interval; it is not the percentage of devices that responded.

How utilization is obtained

Connection	Measurement basis
Serial line, including Modbus RTU	Observed bytes, baud rate, start bit, data bits, parity and stop bits
CAN	Observed frames and bus speed, including overhead, frame format and estimated bit stuffing
CAN FD	Also accounts for nominal and data-phase parameters when known
Transport without physical utilization estimates	Receive and transmit payload rates in B/s, KiB/s or MiB/s

Percentage availability depends on the transport and known line parameters. For example, TCP/UDP show payload rates, not a percentage of network adapter capacity; J2534 measurements depend on its implementation. These statistics distinctions do not extend the beta license scope.

Estimates are limited to traffic visible to the adapter. Unseen retransmissions, losses and echo can affect accuracy. Waiting for a device response and half-duplex turnaround delays are not message transmission time.

CAN bus load and frame rate

The main percentage and compact graph always show CAN bus load. Details combine both series on one chart: a solid bus-load line on the percentage axis and a differently colored solid line for total RX + TX on the frames/s axis. Both independent Y axes sit side by side on the left of the chart, with labels matching their series colors. The legend below the chart shows line samples, names and descriptions on the left, with aligned Max, AVG and Last columns on the right.

A known, applicable guideline appears as a horizontal dashed Adapter limitation line only when it falls within the visible vertical range. The scale follows observed traffic with a small margin; it does not expand to include a reference. Unknown limits are not displayed.

A one-direction reference is not a combined traffic limit. The HEX-USB+CAN 450 frames/s guideline applies to uniform reception, so its line appears only when no transmit traffic is present in the visible range or current sample. Its value is repeated in the Max, AVG and Last columns; the unit appears in the label Adapter limitation · frames/s. The basis is available on hover.

Possible frame loss

At high traffic rates, frame loss may occur due to adapter limitations. Low bus load does not guarantee a complete capture.

Hardware ISO-TP

During an accelerated UDS operation, the graph retains normal CAN colors but uses different source data:

• CAN bus load · ≈ % estimates utilization from completed ISO-TP messages;
• ISO-TP messages · messages/s counts complete RX + TX messages, not individual CAN frames.

Traffic composition separates single-frame and multi-frame messages. Their payload byte counts exclude CAN overhead. A frame-rate Adapter limitation does not apply to messages/s; adapter load is unknown in this mode.

The graph does not show all bus traffic or exact timing between CAN frames. Do not use it to confirm that a capture is complete. CAN frame statistics resume after the operation.

The transport label shows the active CAN or ISO 15765 mode. See choosing hardware acceleration.

History and interval selection

Up to 30 minutes of history are kept in memory. The initial view covers the last minute.

Action	Result
Mouse wheel over the graph, or + / − while it has focus	Changes the visible window between 1 and 30 minutes
Click the graph	Selects a measurement interval
Drag across the graph, or use arrow keys with Shift	Selects multiple intervals for combined statistics
Pause following measurements	Pauses following new measurements; collection continues
Follow the latest measurements	Returns to the latest measurements, clears selection and resumes following the linked trace
Clear selection	Clears selection while keeping the current scale

Zero on the time axis represents the latest measurement; negative time shows measurement age. Missing intervals remain gaps in the graph. A measured 0 % means no observed load during that interval, while — means no available estimate or fresh measurement. When analysis data is not yet available, the panel displays Not enough data.

Disconnecting closes the panel. A new connection or profile change starts a new history. Loading a trace file or virtual playback alone does not create physical line statistics.

Traffic composition

Categories to the right of the graph cover the same visible or selected range. Right-click this area to choose a measure:

Mode	What is compared
Messages	Number of decoded messages or frames
Bytes	Observed byte volume by category
Wire time	Estimated message transmission time; available when calculation data exists

Percentages here are shares of the selected measure, not total line utilization. For example, a PDO share of 80 % in Messages mode means 80 % of counted messages, not 80 % of bus time. In Wire time mode, a category tooltip also shows estimated milliseconds and its contribution to line time.

Modbus RTU categories represent functions and exception responses; CANopen categories include NMT, SYNC, PDO, SDO, Heartbeat and other traffic types. VAG uses known ISO-TP diagnostic addresses, observed TP2.0 channels and other CAN frames. Composition depends on what could be recognized. Undecoded bytes are not counted as individual messages; an incomplete message is counted after decoding completes.

Navigating to Tracer messages

When the open Tracer table belongs to the same physical source, clicking the graph or an error marker moves the table to the corresponding interval. Move the slider in the toolbar to the right of the clear-selection button to navigate to a time in the trace. Selecting a row and manually scrolling the table update the graph's time marker and visible-range outline.

The active Tracer layer and filters are preserved. If no matching rows exist, No trace records in this interval appears and the table stays in place. Times outside the retained history show Outside traffic history.

An error marker links a transport counter to a one-second interval; it does not prove a particular row caused an error. Imported files and separate playback are not linked to current physical measurements.