Design of profibus compatible smart transmitter

The transmitter is a field mounted device used to sense and transmit process variable values over the cables to some remotely placed controller. Keeping an eye on the increased demand for local intelligence of the transmitter in the process industry, a smart transmitter (STx) is designed. This smart transmitter is expected to replace the conventional transmitter following the 4-20 mA current loop standard. A field bus known as Profibus, is selected as a standard for networking STxs, and other devices. The transmitter is designed to have smart features, some of them take care of the various calibrations while others make it more user friendly. All the devices viz. STx, hand held transmitter (HHT) and supervisory computer are networked over a single bus thus reducing the cost of cabling. Profibus protocols are employed for inter-device communications.