If you use a console connection to access and configure the switch, you should connect to the console port of the master node.
The word "Slot" followed by a hyphen and a single decimal digit slot number will be inserted into the prompt in stacking mode. A sample of this prompt is:
* Slot-6 Stack.21 #
The sample indicates a changed configuration (*), the stackable is in stacking mode and is currently using the slot number 6 in the active topology ("Slot-6"), the system name is the default of "Stack", the command about to be executed is the 21st command, and the user is logged in as the administrator on the Master node (#).
There will be no specific prompt that indicates the node role. Run show switch command to discover the identities of the Master and Backup nodes. A successful login on a Standby node will show the ">" character instead of the "#" character at the end of the prompt.