PLC Instrumentation Systems for Small and Midsize Plants
In the more than 40 years since the development of the first Hitachi distributed control system (DCS) in 1975 there has been an emphasis on an inherited tradition in product development. The EX series, released in 1982, saw wide adoption in plants manufacturing intermediate and final products, generally from raw materials in liquid or granular form, in fields including food products, medicine, chemicals, the environment (trash incineration), and small-scale water supply systems.
Around the year 2000 the Japanese manufacturing industry was facing difficult external challenges, including the infl ow of inexpensive products from overseas and a drop in the population of manufacturing workers. In response, many small and midsize plants producing food products and the like actively began introducing automated processes into their operations in order to boost production efficiency. In 2008, seeing this market demand, the companies then known as Hitachi High-Tech Trading Corp. and Hitachi High-Tech Control Systems Corp. developed the Hitachi PD-1 compact instrumentation system combining the general-purpose applicability of a programmable logic controller (PLC) and the analog control functionality of the EX series. The EH-150 series from Hitachi Industrial Equipment Systems Co.,Ltd. was used as the general-purpose PLC.
In most cases in smaller plants each machine is controlled by its own PLC, but the PD-1 utilizes an open network to enable low-cost centralized management of multiple machines. This was a major selling point that motivated many small plants to purchase the system. In addition, the many easy-to-use system building tools developed for the EX series proved very popular.
In recent years the range of applications has grown beyond plants producing food products to include small pharmaceutical and chemical plants as well as R&D facilities. The PD-N01, the current model introduced in 2012, and its successors that will be developed and commercialized in years to come, inherit the DNA of the EX series.
