Hardware executes. Software decides. On an ATM, that includes how a session is authenticated, how a transaction is handled, how the device reports its state, and how updates arrive. Weak software turns good hardware into an opaque box.
On the terminal
Terminal software drives the customer flow, talks to modules, and enforces device-level controls. It must be stable, inspectable, and able to fail closed when something is wrong.
In the center
A management platform holds fleet inventory, configuration, telemetry, alerts, and reporting. It is the system of record for what machines exist, what they are running, and what they are doing.
Between them
The communication path has to be encrypted, authenticated, and operationally boring. Software updates, diagnostics, and telemetry should travel that path without opening a casual remote-control story.