It will be difficult for me to explain to you, since I use the latest version of RapidScada in Russian
You need to create input and output channels for your device.
Create an interface with a button.
In the properties of the button, specify the input and output channels.
Option 1. In the output channel, specify “Use formula”, specify the value 768. This way the button will always send a trigger command to the relay
Just specify in the properties of the button-send the command immediately.
To create two buttons with different purpose-Enable or disable. It will be necessary to make a duplicate of the output channels, in one of them as a formula to specify 256 (Disable), in the other 512 (Enable). Or use a more complex formula in one output channel