Welcome to Hampstead Global Limited

The company offers consultancy in control system automation.

PLCs (Programmable Logical Controller) are often used for small plants where numbers of Inputs/Outputs are less than couple of thousands.  PLCs are also generally used for Package units like; chillers, heaters, dryers etc. In such installations, general control philosophy involves, PLCs executing control of such small units and then sending data across to DCS (Distributed Control System) for display. In some cases, client likes to have all data read in PLC to be sent to DCS. In most cases, client prefers to have only EHS/business/quality critical data sent across to DCS to minimise communication data exchange load.

However, not all installations are package units. In such cases, data is sent directly to DCS using various protocols like; PROFIBUS, FOUNDATION FIEDLBUS, ASI etc. In some cases, inputs and outputs are directly connected to AI (Analog input), DI (Digital Input), DO (Digital Output) or AO (analog input) cards.  Such cards are installed on carrier which is connected to controller of the process. Such cards typically use 4-20ma signal or 24VDC to energise output of DO cards.

Please get in touch with us for your control system automation requirements and also field instrumentation design and support.