System Control Electronics
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8 System Control Electronics
8.1 General Description
The Glovebox is controlled through the use of the Color HMI Touch Screen. It directs box
operation through the lower PLC control box, which generally turns on or off relays to control
box pressure, circulation, purifier regeneration and other functions. Each of these subsystems
are described in this section.
8.1.1 PLC Controller
All inputs and Output are controlled by the PLC.
8.1.2 Display panel
The display panel is Color HMI Touch Screen.
8.2 Lower Control Box
The Lower Control Box houses the following components:
•
Power Supply
•
PLC
•
Connections
•
Solid State Relays
8.2.1 Power Supply
The power supply generates 24 volts DC from an input of 115 volts AC. It can be strapped for
operation at other input voltages. The 24 VDC is for the operation of the upper control
electronics, the lower PC board, and for other miscellaneous components. It can easily be
removed for repair or replacement.
8.2.2 Box Pressure Sensor
This section connects the tubing from the box directly to the on board pressure sensor. The
sensor input is calibrated and provided to the microprocessor.
8.2.3 24 Volt Low Power Relays
This section of the board is where the PLC control lines activate or deactivate the low power
relays. These relays then switch on and off other relays in the system. Note that there is an LED
for each relay on the PLC. When this LED is illuminated, it indicates that 24 VDC is present on
the switched or output side of the relay. When trouble shooting a control problem, this is the
best indication that the box electronics are functioning properly, and that perhaps the higher
power relay is not working.
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