Design of facility Data Acquisition and Control System using Programmable Logic Controllers and Personal Computer Communications Software for use in the Environmental Control and Life Support System (ECLSS) Test Bed is discussed.
Described within the paper is the selection of electrical hardware, computer software and programmable logic controllers needed to acquire data and provide control system functions.
The ECLSS functions are described in reference to control parameters and the use of programmable logic controllers to make temperature, pressure and flow measurements for use in the control system functions, Due to the vast number of analog measurements it became necessary to develop an input multiplexing scheme which will be discussed along with examples of ladder logic and control logic software strategies.
There will also be a brief description of hardware/software interfacing techniques that become necessary to accommodate the various subsystem control schemes and discussion of the method of implementing both automatic and manual control, using ladder logic and programmable logic controllers.
System startup, shutdown and failure mode procedures are discussed in detail as well as calibration and scaling of measurement and control hardware.