The evolution of operator interfaces has moved quite far beyond the pushbutton. Once, the intelligence resided in the operator’s brain, and considerable experience and training were required to operate any complex piece of machinery or process. The evolution of the operator panel is actually two parallel evolutionary tracks. First is the movement of that intelligence from the operator’s brain into the operator panel itself. So, we now refer to them as “smart operator panels.” The other track is how the evolution of the operator panel tracks Moore’s Law, making them more powerful and less expensive.
Smart operator panels permit the
operator to have access to large amounts
of information in one location, on one
or just a few screens. This may include
process data; quality data; performance
of the cell, unit, or batch; or the controls
for the system themselves.
Note the number of data types that can be displayed on the 3.5" operator panel shown in Figure 1; yet, it is small enough to mount directly to a control pedestal or on a machine. This versatility has helped to drive the adoption of smart operator panels in many industries and by many machine builders as well.
A smart operator panel is really a computer — an embedded computer complete with input/output, memory, a processor, and a display (usually a touchscreen) — in an enclosure that is suitable to the environment the panel will be used in, from rack-mount to enclosures that are waterproof or explosion-proof. Regardless of the size of the display, the panel is connected to a field controller, such as a programmable logic controller (PLC) or programmable automation controller (PAC), which controls the machine or process.
The operator panel serves many functions formerly handled by multiple devices. It is a control panel, with pushbutton analogs and displays. It also can be used as a datalogger, sometimes a sequence-of-events recorder, and can provide “help” functions that can assist operators with decision support.
Operator panels are supplied in a variety of enclosures, are often not fan-cooled, and have a variety of displays, mostly flat-panel. The enclosure design varies depending on what the actual inuse environment is for the panel. Panels that are installed in food processing plants or pharmaceutical plants may require waterproof electrical classification enclosures to withstand washdown operations. Panels that are installed in assembly line applications where grime and dirt are problems are usually built without fans for cooling, and are in - stalled in sealed enclosures.
One of the great benefits of smart operator panels is the fact that they can be used to provide human machine interfaces (HMIs) with many controllers. As shown in Figure 2, the operator panel can be connected to PLCs and other operator panels in a variety of useful ways, including remotely over Ethernet, directly over RS-232, and other linkages. This makes communication with the smart operator panel simple and effective, and makes it possible to optimize the uses of smart operator panels without having to buy one for every controller or function in the plant.
There are a wide variety of applications for smart operator panels — many more than just serving as the HMI for a PLC. They can operate to be an HMI for a motion controller or an entire motion control system, even using PLCs or PACs made by different vendors.
They can be used to operate PID control loops and program in function blocks. Because of this, they can be thermal controllers and inverters. With an appropriate controller, they can replace the standard standalone loop controller, and provide benefits like data historian and data logging, multiple loop control capability, and even contextual help functions for operators. They can be used as the communications mechanism and the HMI for smart sensors, and they can act as a microprocessor-based proprietary controller.
The use of these smart operator panels reduces the complexity of wiring, programming, and operation because the panel’s versatility can be depended on to replace many formerly independent devices, like pushbuttons, controllers, data-loggers, and so forth.