By transferring the "brains" from instruments back to PCs,Mescon Technologies has transformed signal conditioning.
The fieldbus revolution has answered this problem somewhat. Decentralized control has heralded "smart" instruments with in-built microprocessor which contained all the relevant transfer functions, configuration and processing information. However, these instruments have their own drawbacks, being a relatively expensive method of controlling a plant.
A third option has recently been developed by Mescon Technologies. Wielding a solution that will provoke the comment "Why didn't I think of that?", Mescon strikes a balance that lies somewhere between centralized control and smart instruments.
Called "Just-PC", the technology uses a PC as the "brain" to be aware of input parameters. The PC then manipulates this information and provides a relatively simple transfer function to the signal conditioner. Rather than contain all the information itself, the signal conditioner contains a relatively small microprocessor with built-in flash memory and firmware that accepts specific transfer functions from the PC.
Mike Weissberg, The Founder of Mescon Technologies said: "The problem with the normal smart instrument is that because of the need for universal input capabilities and universal output capabilities it has become a little monster. It requires considerable digital resources to perform all the possible functions. However, at the end of the day it only delivers a single input/output function and its resources are not really being used."
As an example, if an instrument is supposed to accept ten different types of thermocouples, four different types of RTDs and potentiometers, its memory must contain all the linearization curves and the various algorithms used to perform the measurement. It must contain a large memory, powerful processor and communication for configuration and interrogation purposes. So you end up with a substantial piece of equipment that does a single function, yet contains a tremendous amount of hardware and firmware that is not used very often.
Weissberg said: "The smart instrument is flexible, but this flexibility is being used only a few times in the lifetime of the instrument. It doesn't make sense, as no one can afford to buy $500 to $600 instruments per measurement point. We asked ourselves how we could bring the advantage of digital processing to instruments without the expensive hardware and firmware while enjoying flexibility."
The result was the development of the Just-PC technology which uses the PC to define the input parameters, provide manipulation and transfer function to the instrument. The only function of the instrument is to digitize the signal, provide a standard output and interpret the transfer function. Instead of having an instrument that contains a big memory and microprocessor, you end up with a common instrument platform that is relatively simple, uses a small microprocessor with built-in flash memory with firmware that enables it not only to measure a signal and produce the output but to accept the specific transfer function from the PC. A PC is used to manipulate the data because it's a thousand times more powerful than a microprocessor.
Weissberg said: "The instrument is not intelligent, but the concept is. You finish up with a programmable device which performs as well as a smart device but doesn't contain all the hardware. What's more, it isn't a fixed program device because you can perform whatever manipulation you want - adding new features and functions. If a new task is needed, you don't need to design a new instrument. In fact, we have already modified the software about four times, adding more features each time."
From the customers point of view, the technology is a less expensive solution to signal conditioning that can evolve to suit a changing application. The Just-PC technology is able to achieve its evolutionary ability by eliminating its dependency on hardware. Weissberg said: "We have created a device that will never become obsolete, as you can always increase and update its features and performance."
Mescon Just-PC compliant products are available in Australia through BI Controls, Tel: (03) 9480 0111.