Aeon's Carbon Extraction & Graphitization System and related systems share a simple common control system structure with just a few fundamental elements: A DAQ to monitor Sensors, a set of Controllers to operate Devices, and a Host computer to manage everything and provide a user interface. Here are some brief notes about each element.
The data acquisition hardware. Sensors are wired into the DAQ, which converts their voltages into digital form and transmits them to the host computer. The DAQ also provides a few general-purpose digital I/O (DIO) ports and analog outputs. DIO ports can be programmed for input or output, and each one carries a low-voltage, binary DC signal for detecting or controlling a connected device's state. There are lots of DAQs on the market at every price point and performance level imaginable. We very much like the ones from LabJack.
A controller often operates an array of devices of a single type. Unlike the DAQ, all of Aeon's multiple-device controllers are designed and manufactured by Aeon. The controllers communicate with the host computer via TTL RS-232 over USB. Aeon's controller firmware is open source (GPL3), written in Zilog C. The Actuator and Switchbank controllers plug into an expandable stack of 8-channel device multiplexers. A stack may contain up to eight multiplexers, so each controller can handle as many as 64 devices.
The host computer is a typical Windows laptop. All of Aeon's host software is open source (GPL3), written in C#. The application displays the system state in a graphical diagram, provides direct, manual control of individual devices, and offers process selection and management. The process code is built on Aeon's HACS framework, so it is easy to develop, understand and modify.
A sensor detects some variable condition within the system, such as a pressure or temperature. Most sensors connect to the DAQ, but some are monitored by controllers (like temperature sensors for heaters).
A device is a piece of hardware that does something physical. Simple examples include an actuator that moves an armature, and a heater which changes a temperature. Devices may be complex and contain integrated sensors and sub-devices to perform complicated actions.