Unless you were with Bart Simpson when his class took its field trip to the Springfield Box Factory, who among us has ever thought about the construction of the ubiquitous cardboard box?
Our story begins in a lab. About ten years ago ADI began a program called Circuits from the Lab. This program features hundreds of reference circuits designed and tested by a team of expert application engineers. One of our newest lab-tested circuits uses several new parts that have been arranged for the passing of data across a noisy factory floor. ADI has a long history in this field and is still a leading producer of signal processing solutions for industry. Among the keys to that success are products which can quickly and accurately send and receive data in noisy environments (which pretty much defines most factory floors.) One of our Systems Application Engineers here at ADI explained the new circuit using a box factory as his example:
“Assembly lines are set up to run in a specific way. You might have one machine for folding the cardboard. Okay, so step one is picking up the sheet of cardboard. Step two might be dragging or moving it into position in the machine that folds the sides. Maybe it uses a vacuum to pick up the cardboard. Is the vacuum on? Is it at the right pressure? Has it successfully picked up the sheet and then moved it into the correct position in the folding machine? If the answer to all these questions is yes, then the next machine on the assembly line is given instructions to initiate the fold. All of this information needs to be communicated back to a processor at a central control system.”
This new circuit uses a communication standard called the HART Protocol. Industrial designers like it because it will work with older, analog equipment as well as support more modern digital hardware. (A good analogy would be your high-definition TV, which has inputs for both digital HDMI and analog RGB.) HART also defines a way to check for errors in each transmission, which ensures wrong or corrupted information will NOT get passed to the central processor. More than mangling a few pieces of cardboard, miscommunication from the assembly line to the control processor could result in damaged equipment, which can be costly to repair. The control processor itself is also vulnerable to voltage spikes, so in the circuit ADI engineers included several methods of protecting it from the cacophony of electromagnetic signals floating around the factory.
The circuit can accept data from up to four separate sources. So, going back to our box factory, one board could receive information about the strength of the vacuum, the weight of the piece of cardboard being lifted, the movement of the swing arm – and still have room for one more input. It’s also smart enough to report on breaks in any of the wires connecting the machinery.
The word my engineering colleague used to describe the ultimate benefit of this lab-tested circuit is “confidence.” With a pre-made evaluation board which connects to their PC, evaluation software, and a detailed set of instructions this Circuit can provide a quick path from concept to factory floor. For those interested in diving into the details, as well as ordering information, we invite you to visit the web page on the CN0414 Circuit from the Lab today.
Very nice design and info for a HART solution. PS. There is a small typo at FIg.5. HART OUT pin should have a "DAC".