In the last step of "Events and Subscriptions", there is a note :
This note concern the ThingTemplate VendingMachineTemplate's subscription "ACMETimer30S" rathen than VendingMachineShape's subscriptions, doesn't it ? The Timer subscription will be fired every 30s and will check for a potential problem. The 2 subscriptions of "VMTemperatureHigh" and "VMHumidityHigh" will be fired one after another when we set the VM-TR3's CurrentTemperature and CurrentHumidity.
By the way, the VendingMachineTemplate's subscription "ACMETimer30S" add only 1 tag when it add a stream entry. And the Temperature tags are prioritized because they are the last check and edit of the variable "tag".
It reffers to the ACMETimer30S or any other timer that you set for your subscriptions. For a subscription to run, you will need to have a Timer.
Yes, I'm agree with you. But this does appears at the end of the VendingMachineShape's subscriptions. And the events of these subscriptions are "DataChange", not Timer. It may create confusion in the explanation why there are 2 values in the VendingMachineIssueStream.
The VendingMachineTemplate's subscription "ACMETimer30S" create entries in the VendingMachineProcessValuesStream.