Per-message accumulation

Root-level message_calculations evaluates an expression once per target CAN message and adds the contributions. It uses values in the current message and directly adds each message's expr result. Declare parameters only when the formula needs constants, using names of your choice. Include a time factor when deriving energy from power; add an existing energy contribution directly. Ordinary signal-time integration uses calculations; its timing basis is different.

This page uses the general run entry point. For one ASC/BLF source with all formula inputs in the current message, consider fast; volumes of one recording stay in one source. Held cross-message values, events and individual contribution rows require the general entry. Check supported fields and outputs for the selected engine.

Complete examples and direction groups

message-minimal.yaml uses message-clean.asc and power.dbc. Two messages at 0 s each have ID 0x100 and power 4000 W. With 0.1 s per message, each contributes 400 J, totaling 800 J. Simultaneous messages count separately; they are not deduplicated as signal updates. The record at 1 s falls outside [0,1) and is excluded.

message-directions.yaml uses direction input and direction DBC. It binds Power to power and Direction to direction, then declares separate positive and negative calculations. Direction values at 0, 1, 2 s are 1, -1, 0 and each power is 4000 W. The first two contribute 400 J to their respective groups; zero enters neither group. This example enables contribution details for inspecting skip reasons by calculation ID.

Run either complete file using chronaxis run filename.yaml --output new-result. Formula parameters and direction signals are defined in that file. The BLF example below additionally contains a missing-value message; that record is not part of the minimal ASC input.

The examples declare signal period: 100ms because the public runner initializes validity for used signals. If the DBC supplies no period, give period or valid_for explicitly. This signal period is not multiplied into the contribution again: the formula's separate parameters.period controls each contribution, and the fields are not automatically linked.

Message energy: 4000 W × 0.1 s × 2 = 800 J

Use message-energy.yaml, which defines power and has one CAN source, selected automatically. Replace its root message_calculations list with this block; do not nest the parent key inside a list item.

yaml

message_calculations:     # Evaluate and accumulate each target message
  - name: energy          # Calculation name in results
    update_message:       # Message that triggers one evaluation
      frame_id: 0x100     # ID from the DBC
    parameters:           # Constants referenced by the formula
      period:             # Duration represented by one message
        value: 0.1        # Period from protocol or business rules
        unit: s           # Seconds
    expr: power * period  # Contribution from this message
    unit: J               # Contribution and total unit

Two simultaneous 4000 W messages contribute 400 J each; a third missing-value message is skipped as missing_input. Non-target IDs are not attempts. The total is 800 J from 3 attempts, 2 contributions and 1 skip. This period is explicit and fixed; it is neither inferred from nor multiplied by actual inter-message time.

All calculation fields

The main table describes message_calculations[]. Nested tables describe update_message, parameters.<parameter_name> and split_by_sign inside each item. A parameter name such as period is used in the formula; do not place value directly under parameters.

Field	Type	Required/default	Meaning
name	String	Required	Unique calculation name such as energy; must not duplicate another generated node.
source	String	Required when multiple sources qualify; otherwise the unique raw-message source	Existing asc_or_blf, can_blf, can_asc or raw_can_csv source name. All referenced target signals must belong to this source and message.
profile	String	Inferred from source	Normally omit. can_blf uses `sclicer-functions-v1`, consistent with its implementation; asc_or_blf, can_asc and raw_can_csv use `can-text-v1`.
operation	String	Default `legacy_sum`	Only `legacy_sum` is supported: add successful evaluations.
message_policy	String	Default `current_message-v1`	Only current-message values are used. `cache_policy` is not supported; missing inputs are not taken from other messages.
update_message	Object	Required	Message identity triggering evaluation; fields below.
expr	Expression string	Required	Contribution per target message, e.g. `power * period`. Uses this message's signals and this calculation's parameters, not ordinary derived signals or values from another message. See Expressions.
unit	String	Required	Physical unit of each contribution and the total, such as J. It does not add another time integration.
parameters	Object	Default `{}`	Named constants, each with value and unit; names are referenced by the expression.
split_by_sign	Object	Default no direction filter	Accumulate only a selected positive/negative direction group. Declare two differently named calculations to get both groups.

Only frame_id is required in update_message. Channel inherits the source; frame flags are inferred unless matching is ambiguous.

Field	Type	Meaning
channel	Integer	User channel numbered from 1, matching the selected source. Channel 1 maps internally automatically; do not subtract one.
frame_id	Integer or string	Required DBC message ID. Prefix 0x means hexadecimal, 0b binary, otherwise decimal. Use strings for prefixed IDs in JSON. Ranges match CAN bindings.
is_extended	Optional bool	false for standard, true for extended IDs; omission infers the frame type. Equal numeric IDs with different frame types remain distinct. Explicit null is invalid.
is_fd	Optional bool	false for classic CAN, true for CAN FD; omission infers from actual frames. Explicit null is invalid.

Each parameters.<name> requires both fields, without defaults:

Field	Type	Meaning
value	Number	Finite float64-compatible constant, such as 0.1 for a period; not bool, string, NaN or Infinity. Obtain it from protocol or business requirements.
unit	String	Actual unit, e.g. s for period or `1` for a dimensionless factor; not a descriptive comment.

split_by_sign requires signal and bucket; value_policy defaults to raw_decoded-v1:

Field	Type	Meaning
signal	String	Numeric or bool direction signal alias from the same message. It need not appear in expr.
bucket	String	`positive` selects raw direction >0; `negative` selects <0. Zero enters neither. Bool true is positive and false is zero.
value_policy	String	Only `raw_decoded-v1`: use the freshly decoded direction before scale, offset or direction conversion, without retaining a previous value.

The direction signal selects the group; the expression determines the amount. A positive direction with a -10 J expression adds -10 J to the positive group, without absolute-value conversion. Zero enters neither group. Each group's final value is retained to six decimal places. No participating messages is different from valid +10 J and -10 J contributions summing to zero. See the complete message example.

Totals and contribution details

Use outputs.contributions: none when only totals are needed. Public calculation results retain value, unit, status, reason, quality and calculation identity, without attempt/skip counts or per-reason counts. Choose full and read contributions when individual contributions and skips are needed. Diagnostics separately controls detailed input/configuration information.

Omitting dataset.domain accumulates all files from the referenced CAN source. Keep the required dataset object and its name field. Default reader.input_check: auto does not create a time range solely for this time-independent task. When dataset.domain is specified, its start and end times filter the messages.

full records each attempt; none avoids unnecessary details. Performance still depends on the actual input and calculation combination.