Controlling the digital outputs on displays is done by setting the variable associated with the output to "0" or "1" using a calculation event or by firing the action Digital Output High/Low. Which method is used changed over the years depending on which hardware platform you are using and which version of Powervision.
In version 2.9 the action method is used on both the PV780 and PV380 displays.
Most of the outputs are low side switches, meaning they will switch the negative side of the load to ground. Keep this in mind when testing, generally you cannot just connect a multimeter to the output and measure voltage to determine if it is switching on and off, you need to have an active load connected to test with.
ALWAYS use a flyback diode connected in reverse polarity across the coil of any inductive load like a relay coil. This will snub the voltage spike that is generated by the coil when the output is switched off that would otherwise damage the output.
The following two configurations demonstrate the two methods of controlling the outputs on a color and monochrome display. See the notes in the Configuration Tab. These were created in Version 2.9.23029