Understanding AWS Billing for IoT Core

AWS IoT Core billing is divided into several categories, each representing different aspects of IoT device management and communication. Here's a breakdown of the charge categories you mentioned:

1. AWS IoT USE1-ActionsExecuted: This refers to the number of actions executed as part of the AWS IoT Rules Engine. When a rule is triggered, it can perform one or more actions, such as sending a message to another AWS service or updating a device shadow. Each action executed is counted and billed separately.

2. AWS IoT USE1-ConnectionMinutes: This category measures the total time devices are connected to AWS IoT Core. It's calculated in one-minute increments based on the duration of device connections.

3. AWS IoT USE1-Messages: This represents the number of messages transmitted between devices and AWS IoT Core. This includes both messages sent from devices to the cloud and messages sent from the cloud to devices.

4. AWS IoT USE1-RegistryAndShadowOperations: This category covers operations that access or modify Device Shadow data or the device registry. Device Shadows are used to store and retrieve current state information for a device, while the registry is used for device management.

5. AWS IoT USE1-RulesTriggered: This refers to the number of times rules in the AWS IoT Rules Engine are initiated. Each time a rule is triggered (usually by an incoming message), it counts towards this category.

Each of these categories has its own pricing structure, typically charged per million units (e.g., per million messages, per million minutes of connection, etc.). The "USE1" in the category names indicates that these charges are for the US East 1 region.

It's important to note that these charges can accumulate quickly depending on your IoT implementation. For example, a single published message could trigger multiple rules, each executing multiple actions, resulting in charges across several categories for what might seem like a single operation.

To manage costs effectively, it's crucial to monitor your IoT Core usage, optimize your rules and message patterns, and consider using features like basic ingest for publishing directly to rules without incurring additional messaging charges where applicable.
Sources
Securely Connect IoT Devices – AWS IoT Core Pricing – Amazon Web Services
Billing groups - AWS IoT Core
AWS IoT Device Management Pricing - Amazon Web Services
AWS IoT Greengrass