Digital indicating controllers for single-loop applications

Paul Boughton
Yokogawa Electric Corporation is releasing the UT35A (one-quarter DIN size) and the UT32A (one-eighth DIN size) entry-level models in the UTAdvanced series of digital indicating controllers. These new low-cost models, which replace Yokogawa's UT300 range, have a sequence control function that is based on the general-purpose ladder logic programming language; they are targeted for use in the single-loop control of production equipment.
The UTAdvanced Series adopts an open system architecture with an Ethernet communications interface. The units are compatible with the Modbus/TCP protocol and also (as an option) the Profibus DP protocol. In addition to eliminating the need for dedicated communication programs and converters for connecting to devices such as data acquisition units and/or PLCs, this feature makes it easy to develop optimal multi-vendor systems.
Yokogawa says the first models in this series, the UT55A and UT52A, have gained a solid reputation for their contributions in raising efficiency and lowering costs by integrating peripheral devices such as relays. These high-end, high-performance digital indicating controllers have a wealth of control function modes, with the most capable units able to perform full cascade control for controlling relatively complex installations such as continuous furnaces.
However, there is also a need in the market for general-purpose indicating controllers that have only the functionality needed for controlling single-loop production equipment. To meet this need, Yokogawa is releasing the UT35A and UT32A entry-level models. These have a fixed control scan period of 200ms and 300 steps for ladder programming, compared with the three control scan periods and 500 steps in the high-end UT55A and UT52A models. However, this is more than adequate for the single-loop control of production line installations.
The UT35A and UT32A also have capabilities that would normally only be found in high-end controllers, including: a ladder language-based sequence control function; support of the Ethernet or RS485 interfaces and Modbus or Profibus-DP communication protocols; a colour LCD display; and operation guidance functions including navigation keys.
Also included is a user default function. Not only is it possible via a simple function to reset the unit to factory default settings, but it is also possible for users to define their own 'default profile' to which it is possible to return. This means that an engineer can always quickly revert to a known working setup profile - without starting again from scratch or having to load a configuration file from a PC.
Main target markets for the new controllers are machining facilities in a wide variety of industries including electrical equipment, machinery, chemicals, foods, semiconductors and automotive manufacturing.
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