Sending Downlink Port Number From Button in Dashboard

Sending Downlink Port Number From Button in Dashboard

I successfully am sending downlink payloads using the default port number specified in the 'Environment Variables' of the Analysis.

What I cannot figure out is how to get a button to send both the payload AND the port number to the Analysis.

The example only shows how to do this using an Input Form.  Can it be done with a Push Button?