I want one thing to do a lot of things.
If there’s a mantra for the 21st-century consumer, this is it. Swiss Army knives are on the map for multi-purpose functions. It’s why we call smartphones smart. The problem is that consumers want all this multi-function wizardry and they want ease-of-use as well.
These concerns topped the list when Watlow designed its new F4T temperature process controller. The primary goal for the development of the new device was to ensure that it would be easy to use without sacrificing application flexibility. Because many of Watlow’s target customers were already using its SERIES F4 controller, the bar was set high for ease-of-use. The F4T’s color, graphical touchscreen user-interface and configuration software had to let OEMs and end users tailor the controller to specific applications.
The F4T controller combines the functions of many devices, including temperature PID, over/under temperature limit, power switching, math, logic, and timers and counters into one integrated system. The controller has field pluggable I/O, programmable function blocks and an ambient operating temperature of 0 to 122° F. For connectivity, the F4T has a graphical configuration PC software that connects with the controller through Ethernet. It also has agency certifications such as UL, FM, CE, RoHS, W.E.E.E. and NEMA 4X/IP65. Communications options include Ethernet Modbus TCP and SCPI and EIA 232/485 Modbus RTU.
Clearly, many challenges come into play when developing a product with such a density of features. The F4T requires time critical measurements, advanced control algorithms, support for industrial communications protocol interfaces, management of multiple tasks in embedded software, field pluggable I/O hardware, onboard agency-approved safety devices and robust mechanical design.
User experience is often a factor for design teams, but it’s not always central to the design efforts. The challenge for the F4T team was to design for ease-of-use without delaying product development.
The team started by defining their type of users—operators, OEM engineers, lab managers and line-maintenance technicians. People in these roles participated in testing to help the F4T team lay out the functions and features of the interface. For example, in an initial card-sort test, the subjects sorted operations and functions, such as “changing the temperature units,” into categories they defined themselves such as “operation,” “set-up” and “maintenance.”
Based on these tests, the F4T team developed a grouping of information and controls for each of the tasks. This organization served as a blueprint for the interface. From there, a wire-frame prototype was developed with several iterations tested internally. Next, an HTML-based prototype was developed and tested by samples of the target user populations.
The next challenge was getting a product that was still in development into the hands of test groups. The usability testing was performed through web-based conferences with a moderator administering a scripted test in which subjects interacted with the prototype using a web browser and mouse. The moderator asked the subject to perform tasks such as, “Can you show me how you would change the humidity set point?” Measurements included successfully completed tasks in a preset amount of time and how often users made wrong turns. After each set of tasks, users were asked follow-up questions to determine if they understood what they had seen. They were then asked to rate the ease-of-use of the functions. These test sessions were observed by the F4T team so they could directly witness the users’ frustrations when features were not easy to use. The prototype was updated as they discovered the problem areas.
The same process was applied to the Composer software that can be used to set up the F4T. The software testing also shed light on areas that could be adjusted. In one example, a subject was unable to find a button on a screen that was required to complete a task. By debriefing the participant and reviewing the recording, designers were able to determine that the color combination (white text on a grey background) and placement of the button (low on the screen) was causing a problem. The farsighted participant had trouble with this when using a laptop with an LCD monitor. To make the button easier to locate, the team moved the button and changed the color combination to a higher contrast (white text on dark blue). In future tests, this problem no longer occurred.
After this testing, the F4T team refined the interface design before the product was even created. Typically the user-interface is the last thing you can put in the product. But had the Watlow designers waited until the touchscreen was functioning to begin testing, it would have delayed the product and comprised the ease-of-use. Their approach is a great example of how to develop an interface parallel with the hardware and software. The testing and the prototypes cost much less than actual product iterations, saving time and money and creating better end results.