K-BOX: conversion tables and formulas

Make K-BOX channels read in engineering units, such as kPa from a pressure sensor, and carry those conversions into your logger software through the DBC file.

Tables or formulas

K-CAL gives you two ways to map a measured value to an engineering unit:

• Conversion table: a list of points that describe the sensor's transfer function. Use it for a sensor that is not linear.
• Formula: a straight line, Y = a × X + b. Use it for a linear sensor.

A channel uses one or the other. You work on the Measurement tab, where K-CAL shows each channel's measured value beside its converted value. For that tab, see K-CAL: viewing live data on the oscilloscope. The Tables and Formula buttons are not available for K-TC modules.

Create a conversion table

This example converts the output of a pressure sensor, in mV, to kPa.

1. Open the table editor. Select Tables > Edit. The Edit Conversion Tables window opens.
2. Start a table. Select New.
3. Name it and set its unit. Enter a Name, for example V-PA, and the Y Axis Units, for example kPa. The X axis is always the measured value in mV.
4. Add the points. Select Add for each point of the sensor's transfer function. The graph shows the curve as you go.
5. Save the table. Select Ok.

Apply a conversion table to a channel

1. Select the channel. Find it on the Measurement tab, for example ADC 0 under Analog Channels.
2. Check for an existing conversion. If the channel already has a table or a formula, the Tables or Formula button is highlighted in red. To remove it, open that button's menu and select Not Use.
3. Choose the table. Select Tables and then the table name, for example V-PA.

K-CAL applies the table at once. The channel display shows the measured value, the converted value and the name of the table in use.

Apply a formula to a channel

1. Select the channel. Find it on the Measurement tab. If it already has a table or formula, remove it first with Not Use.
2. Open the formula editor. Select Formula > Edit.
3. Enter the formula. In the Edit Formula window, enter a, b and the output Units. For example a = 0.75, b = 12.3 and units N m give Y = 0.75*X+12.3.
4. Apply it. Select Ok. K-CAL applies the formula at once and shows it beside the channel.

Export a DBC with the conversions

Select Export on the toolbar. K-CAL generates a DBC file and asks where to save it. The file includes the conversion tables and formulas of the analogue channels. DIALOG, or any other tool that reads DBC files, then shows the same engineering units. If K-CAL should reload the channel settings from the module first, tick Load at export on the General tab.

To bring the DBC into DIALOG and log K-BOX with a REBEL, see K-Series: logging module data with REBEL and DIALOG. For background on DBC files, see Understanding CAN DBC.

Watch: How to export a CAN DBC using the K-BOX (1:28)

Next: K-BOX: calibrating inputs and updating firmware.