Min/Max tracking of multi-channel digital meter with alarms
A Min/Max chart is a digital display of minimum, current and maximum data values for each channel.
Warning and alarm level exceedance indicators are provided on a per channel basis. Note that these are currently used only in the single channel digital display and the test run time Min/Max chart displays.
The Min/Max values are tracked for the lifetime of chart control:
- If a test is started with a Min/Max chart open, the values will be tracked until the test is stopped, the chart is closed or the browser is closed or refreshed.
- If a test is started (time = 0 seconds) and afterwards a Min/Max chart is opened (time = 5 seconds), any min/max data between time = 0 and time = 5 will not be tracked.
- If a Min/Max chart for a channel is closed and another Min/Max chart is opened for that channel, the Min/Max chart will show data only from after its opening.

Specify Range min, Range max, Alarms and Warnings min and max in Test Configuration in the Scaling mode section of the Edit channels dialog or the grid interface.
- 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.
See also User preferences, General menu item for Decimal point handling of Range min/max values.
The following options are available from the menu. Click the options menu button:
- Freeze: Select to pause the data display. Deselect to resume live data.
- Reset: This resets the minimum and maximum values.
- Update rate: Select the rate at which the display refreshes at 1, 2, 5 or 10 times per second. Note that in cases where the channel sample rate is less than the selected update rate, the display refreshes at the lower sample rate.