The frequency output is designed primarily to drive analog gauges that respond to a frequency input like an analog tachometer or speedometer. It can also be used for any other suitable application where a frequency signal is required. Please note this article only covers operation of the Powerview line of displays.
The output consists of a 2K ohm pullup resistor connected to Battery +. A low side FET then switches this voltage to ground at the rate set by the frequency output variable. The output will appear as a square wave form with a 50% duty cycle. Please see the product specifications to obtain the frequency range for the display model in use.
Powervision Release 7.x: The default condition at power up is for the output to be 0Vdc. Please note there is a small period of time < 1second where the output will be high at power up until the processor boots up and sets it low. When the frequency variable is set to 0Hz, the output will be driven low or 0Vdc.
All Previous Powervision Releases: The ouptut is non-deterministic, it can power up in either a high or low state. Likewise when setting the frequency variable to 0Hz the output may stop in either a high or low state.
Enabling Frequency Output
To enable the frequency output go to the Connections tab, select frequency output, then select the auto create variable check box. You may also link the output to a pre-existing variable. Use any of the programming tools to set the desired frequency value in this variable.
If you do not see frequency output in the connections list or you cannot select it then verify you have the correct display hardware model selected. Many of the HVxxxx model of displays for example do not have this enabled.