Did Someone Say Control? Deciding on a Control System Architecture

With the increase in capabilities of programmable logic controllers (PLCs) to provide faster processing speeds and data capture, the once clear line between a data acquisition system (DAQ) and PLC in a testing environment has become very fluid. It can be a challenge to develop a control system architecture that identifies what systems and equipment are best controlled from a DAQ system, a PLC, or a building automation system (BAS). Each offers advantages. It is often primarily a function of the users’ preference and level of experience with operating and maintaining the system.

The complexity of a control system architecture requires careful consideration for current and future testing needs. The two most important questions I ask when helping clients choose among control system options are:

What level of experience do your test equipment operators have with any control platform?
Who will ultimately be responsible for operating and maintaining the system?

The best outcome when developing a control system architecture is to combine the capabilities/advantages of a DAQ, PLC, and/or BAS into an overall platform that provides:

• An operator interface and communication with the unit under test – that the owner can operate and maintain.
• Building facility controls that support the test environment and meets the needs of facility operations staff.

Asking the right questions at the start of a project helps ensure that the system we design will serve the client and meet their needs.