Overview

All ThingsPro Gateways (e.g., UC-8112-LX-CG) come pre-installed with a Data Acquisition Framework. As indicated by the name, the Data Acquisition Framework is set of services that help you develop Data Acquisition applications.

The Data Acquisition Framework typically consists of the following services:

Broker Service, which dispatches subscribed Tags to individual sub-services

Storage Service, which stores Tags of interest into Log Files

Upload Service, which uploads Log Files to remote servers

Note: Refer to the ThingsPro User's Manual for additional details on the Modbus Management Framework.

This tutorial explains the usage of the libmxidaf API. You can use the libmxidaf API to acquire data, log, and tag values from other devices or sensors for your data-acquisition applications.

Use the libmxidaf API to:

• Publish Tags to the Data Acquisition Framework.
• Subscribe to Tags in the Data Acquisition Framework.
• Read Tags from the Modbus Management Framework.
• Write the Modbus Tag values into the Modbus Management Framework.

When you import a Tag from the Modbus Management Framework or through the libmxidaf API into a Broker Service, it is dispatched to the Storage Service or to applications called subscribe functions through libmxidaf. If a Tag is configured for logging, the Storage Service saves it to a Log File.

Note: The code snippets used in this tutorial have been simplified for clarity. Refer to Reference for the complete code.

libmxidaf

The libmxidaf API provides interfaces in C and Python.

The structure of a Tag is modeled on the basic structure of a device reading and consists of the following three components:

• Value of Reading(value)
• Time of Reading(at), in UTC
• Unit of Reading(unit)