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Technical Details
Overview
The Shadow Pneumatic Control Unit is an integrated control system allowing rapid setup and prototyping of pneumatic systems. It can also be used as part of a fixed installation.
Layout of the System
Figure 1: Block Diagram of SPCU
Front Panel
The Front Panel provides four 4mm air ports (Actuator 1..4), 8 3-way
connectors for sensors (A0..A7), an LED to indicate valid system power,
and a Reset button.
Back Panel
The Back Panel provides a 24V power inlet connection, a 9-pin D connector for RS-232, and a 6mm air port for compressed air in.
Dimensions
The SPCU box, including the connectors, measures 320x105x60mm and weighs 1.3kg.
Actuator Ports
An Actuator Port is where a pneumatic actuator is connected to the SPCU. It provides a switched source of compressed air for one actuator channel. Multiple actuators can be connected to an Actuator Port.
Sensor Inputs
A Sensor Input is where a sensor can be connected to the SPCU. The Sensor Input provides 5V DC power for the sensor to operate. The Sensor Input is read by the ADC, and the results fed to the MCU for processing.
Valves
Eight on-off (2/2) pneumatic Valves are installed in the SPCU. They are set up to allow an Actuator Port to fill, leave inflated and empty the attached actuator. The Valves are driven from the MCU, either using sensor-based control or timed commands from the host.
Serial Port
A standard RS232 Serial Port is fitted to the SPCU so it can be conveniently run from a wide range of Host computers. Commands sent over the Serial Port enable and disable controllers, switch valves, read sensors, and provide controller targets.
Reset Button
The Reset Button allows the MCU to be reset into the "Power-On" state. When the Reset Button is pressed, the MCU will return all settings to those stored internally.
Power Input
24V DC is fed into the Power Input. This is used to power the Valves and the MCU as well as providing 5V DC on the Sensor Inputs.
MCU
The MCU (MicroControllerUnit) is the heart of the SPCU. It handles timed switching of the Valves, reading values from the Sensor Inputs, running Controllers on the Valves and talking over the Serial Port to the Host computer. The MCU has non-volatile storage, so it is possible to configure how the SPCU will behave from power-on.
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