A blinding solution

PLCs and Scada packages have enabled one of Europe’s leading suppliers of solar shading control systems to take a major step forward in building management

Guthrie Douglas of Warwick has developed a reputation for its innovative approach to control system programming, which anticipates low sun angles as well as detecting and reacting to changes in the atmosphere. The latest solar shading control system from the company is the advanced desktop PC-based called Pilotpc.

Guthrie Douglas was looking to upgrade its 10-year-old purpose-built intelligent interface for controllable shading. Senior electrical engineer, Howard Weaver, said: “Over a six month period, I looked at many Scada-type packages, most of which were tag limited, making them expensive for the amount of data transfer we needed. Then I found Omron’s Sysmac-SCS software package, which offered unlimited tags for the same price. It was very cost-effective and more than flexible enough for our needs. I found it easy to set-up and configure with its intuitive programming – and its pre-set functions and animations saved a lot of programming time too.” The Pilotpc system with the Sysmac-SCS Scada package gives a display of the blinds throughout the whole building and provides all communications, data logging, calculation of the sun’s position, and many other functions. By eliminating glare and regulating solar heat gain, solar energy heats the building only when it is desirable. The system can also be configured to close the blinds in dull/dark conditions and signal to the lighting system that backlighting is required.

To achieve this, the Pilotpc system is configured with information about the global position and orientation of the building, and the types and positions of shading equipment fitted to it. It uses this data in conjunction with the time-of-day and date to determine where, at any moment, the sun will affect the building. External light and temperature sensors provide the environmental information to enable the system to decide when and where to deploy blinds.

Omron’s compact CPM1A micro programmable logic controllers (PLCs) and SRMI remote I/O PLCs are used as motor control outstations around the building for the local adjustment of blinds. The outstations control and switch the power to the motors in a local area, which might be a single floor on a multi-storey building or a single building in a multi-building complex. This substantially reduces wiring costs and the overall installed system costs.

Each outstation initiates a drive cycle to open or close tension (fabric) or vertical roller blinds, gives timed pulses to tilt venetian blinds or, using a closed loop drive sequence with feedback from motor-mounted potentiometers, adjusts the movement of external rotating louvres to a fixed position.