CAN channels

CAN channels use Vector CAN databases or eDAQ CAN databases to decode specific signal values from incoming CAN messages on an eDAQXR, MX471B-R or MX840B-R CAN connector.

NOTE
The eDAQ CAN databases are currently supported only by the CX23-R/eDAQXR CAN interface. They are not currently supported by the MX471B-R or MX840B-R CAN interfaces.

The MX471B-R and MX840B-R support up to 128 database channels for each CAN connector. There is no limit on the number of database channels for unit CAN connectors. The unit also supports active queries (SAE® J1939-21 PGN requests) on up to 75 database messages per CAN connector.

ClosedGeneric parameters

  • Connection: A unique hardware identifier created by the system.
  • Name: The channel name must be unique and contain valid characters (invalid characters are single and double quotes, '\', '@', '#', '&', '<' and '>'). Invalid channel names are 'true' and 'false' (case sensitive).
  • Description: Enter an optional detailed description of the channel.
  • Measurand: Enter an optional measurement type.
  • Data type: The format of the channel data output (read only).
  • Collect: Select the Collect checkbox to write the channel data to the SIE data file during a test run.
  • Sample rate: Select the desired channel sample rate. If the sample rate changes, all dependent computed channels and DataModes™ are changed automatically.
  • Custom column information: Enter the desired information. The system treats all input as free formatted text. This means it will sort alphabetically, but not alphanumerically (e.g., input values of “1”, “2”, “11”, will be sorted descending as “1”, “11”, “2”). Use leading zeros to realize alphanumeric sorting.
  • Range min / Range max: Enter the desired full scale range min and max values in physical (engineering) units. For all channels, they are used as the default min and max bounds for histogram DataModes.
  • Alarm min / Alarm max: Enter the desired values for min and/or max alarms as a physical units value or as a % of Range min/max value.
  • Warning min / Warning max: Enter the desired values for min and/or max warnings as a physical units value or as a % of Range min/max value.
  • Chart type: Set the default chart type for the channel. Not in edit dialog.
  • Decimals: Select the default decimal places for channel displays. Use the “Auto” option to apply the settings defined in the User Preferences. See User preferences > General > Decimal point handling for more information.
  • Expiration time: Specify the time period in seconds that can elapse without data arriving on the CAN bus before data is considered stale and the output is set to the invalid value. The value may be any real number greater than zero.
  • Invalid value: Specify the value to be set when the expiration time has elapsed without any data. The value may be any real number.
  • Hardware interface: Value is CAN.
  • Bit rate: Set the bit rate from the drop-down list of valid values. If the CAN bit rate is changed, all channels on the same port are changed to the same bit rate value automatically.
  • Termination: Set the state of the internal termination resistor as true or false. If the termination state is changed, all channels on the same port are changed to the same state automatically.
  • Request msg: For unit channels, value is a hexadecimal representation of the SAE® J1939-21 compliant PGN request. This value is read-only and computed based on the CAN message ID. Only applicable when the request rate is set (not Off).
  • Request rate: For unit channels, optionally set the rate for active query requests. When set (not Off), the unit transmits SAE® J1939-21 compliant PGN request messages at the specified rate. Since, request messages are only requests, they may or may not be honored by the connected CAN device. Request messages are only transmitted during a test run.

ClosedScaling parameters

  • Scaling mode: Set the channel scaling mode.
  • Electrical units: Electrical units of channel input. This is fixed by the system and cannot be changed. The defined sensor scaling is used to convert data from Electrical units to Physical units.
  • Units: Physical units of measurement for the channel.
  • Electrical 1: Specify for Defined two point scaling mode. Automatically set after Experimental two point scaling.
  • Physical 1: Specify for Defined two point scaling mode. Automatically set after Experimental two point scaling.
  • Electrical 2: Specify for Defined two point scaling mode. Automatically set after Experimental two point scaling.
  • Physical 2: Specify for Defined two point scaling mode. Automatically set after Experimental two point scaling.
  • Electrical zero: Specify for Defined zero span scaling mode.
  • Electrical span: Specify for Defined zero span scaling mode.
  • Physical span: Specify for Defined zero span scaling mode.
  • Slope: Specify for Defined slope intercept scaling mode.
  • Intercept: Specify for Defined slope intercept scaling mode.
  • Prerun zero mode: Set to Interactive only to allow channel zeroing.
  • Prerun zero offset: Automatically set after zeroing a channel. The user can edit this, but that is not generally advised.
  • Prerun zero target: Specify the physical value desired for the zero task. Typically, this is 0.0, but not always. For example, this parameter may be set to 1.0 (g) for an accelerometer that senses the force of gravity. In this example, the zero task would result in the channel data being offset so that the current reading is 1.0.
  • Range min and max: Specify the expected extreme values of the channel. These parameters are most significant for the EBRG and EHLS layer channels because they are used to set the signal conditioner gains and offset. For other channel types, they are less significant. However, for all channel types, they are used as defaults for the histogram bounds in applicable data modes, and they can also be used as default y-axis limits for strip chart displays.
  • Warning and Alarm min and max: Specify the desired values for warning and alarm thresholds.
    • Enter a real number that defines the level in physical units, or a real number followed by the ‘%’ character that defines the level as a percent of Range max or min, or leave the cell blank to inhibit the warning or alarm.
    • The percent value must be in the range of 0% to 120%.
    • The % of Range max is independent of Range min and vice-versa. For example, if Range max is set to 1000 and Range min is set to -500 and 90% is used for both alarm levels, the alarms trip when the data value becomes > 900 or <-450. If the user changes the Range min to -600, the Min alarm threshold changes to -540. However, the Max alarm threshold does not change (i.e., it is still 900).
    • The values of the warnings and alarms, in terms of real numbers, must satisfy the following condition for all defined parameters:
      Min alarm threshold < Min warning threshold < Max warning threshold < Max alarm threshold.
    • A min or max warning will show a yellow background for the numbers.
    • A min or max alarm will show a red background for the numbers.
  • Max electrical: This field is applicable to MXB modules only. It is used to set the signal conditioner gain and resultant measurement range.