Output Configuration Tab - 1794-VHSC
Use this tab to configure the On/Off values for the 1794-VHSC module.
Parameters
Counts/Hertz
Select the units used for the On and Off values. By default, Counts are used and the Hertz setting is disabled. This setting is active, however, for the Period/Rate, Continuous/Rate, and Rate Measurement Modes.
Tip: | The VHSC module uses Counts in evaluating the On/Off values. If you choose Hertz, the values you enter are converted to counts by the module, so that when it is updated, it has count values that correspond to the selected frequencies. If you return to the Output Configuration tab after you have configured your values in Hertz, they will be displayed once more in Counts. Simply click the Hertz button to see the values again in Hertz. It is important to note that when the values are converted to counts, the calculation results in an integer, and round-off errors may occur. You must be aware of this if you switch back to Hertz values. |
For Period/Rate and Continuous/Rate, the conversion formula is:
counts = (Scalar X 2500000)/desired frequency
For Rate Measurement, the conversion formula is:
counts = time base X gate interval X desired frequency
On Value
The count at which to turn on the selected output(s) for the appropriate counter. Valid values range from 0 to 16,777,215.
The
On Value must be less than the Rollover to function. If an output is associated with a window, On cannot equal Off.
Off Value
The count at which to turn off the selected output(s) for the appropriate counter. Valid values range from 0 to 16,777,215.
The Off Value must be less than the Rollover to function.
If an output is associated with a window, On cannot equal Off.
Outputs
One of the four current sourcing outputs available on the VHSC module. These outputs turn on within 25 ms when the appropriate count value has been reached.
For example:
Tip: | If an output uses several windows from the same counter, the values in the windows may be overlapping. You can assign any output to any count window with no restrictions. The outputs may be overlapped to prevent a control output from dropping out while different conditions for the output remain valid. |
Example: | Output 0 is selected for both Counter 0 Window 1 & Counter 0 Window 2. The ON Value for Window 1 is 200 and the OFF Value for Window 1 is 800. The ON Value for Window 2 is 400 and the OFF Value for Window 2 is 600. How does Output 0 behave? Output 0 should remain on until both Window 1 and Window 2 are off. |
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