Overview
How do you maintain a facility at optimal temperature and humidity conditions for a textile weaving process, yet maintain reasonable energy costs? Answer: you put in new high efficiency lights, install insulated windows and doors, add sky-lights, a highly efficient centrifugal chiller; and finally, you put in an intelligent environmental monitoring and control system like the one at the Interface Fabrics' Weave 2 facility. Working with the client's environmental consultants, we designed and implemented a PC-based control and monitoring system.

Because temperature accuracy is important to determine the performance of HVAC systems, thermistors and a highly accurate data acquisition/switch unit were required to achieve the accuracy needed. Normally, the data acquisition/switch unit must be located close to a PC. In this case, however, communications with the switch unit was accomplished with a Lantronix Ethernet to serial "device server". This decision allowed the unit to be located centrally, minimizing thermistor installation cost. And we were also able to locate the PC an office environment, away from the harsher environment of the plant floor. We also minimized the cost of control wiring to the chiller and air handler units by using fieldbus I/O.

We used Wonderware FactorySuite for the operator interface (InTouch), control software (InControl), and remote alarming and paging software (SCADAlarm). Descartes OmniServer collects data from the data acquisition/switch unit. We developed the necessary "protocol" to instruct the unit to acquire and send the desired environmental information, and soft PLC and OPC software interface with the fieldbus I/O.

Because environmental consultants and engineers were located throughout the U.S., remote control and dial-up connectivity was essential. Using native Windows 2000 dial-up networking and Netmeeting, the consultants are able to dial-in, view the system status, and retrieve historical system data.

Features/Benefits
• Fuzzy control algorithms for chilled water valve, hot water valve, damper and fan speed control.
• Operator interface and controller software on one highly reliable computer.
• Ethernet fieldbus I/O.
• Oversized buttons for touch-screen operation.
• Trending for problem diagnosis and system performance evaluation.
• Data storage in a MS Access database.
• Data retrieval with MS Excel.
• Serial-over-Ethernet communications to Agilent 34970A data acquisition/switch unit..
• Remote control and dial-up networking.

Development Tools
• Wonderware FactorySuite 7.1 (InTouch, InControl & SCADAlarm)
• Descartes OmniServer OPC Server
• Beckhoff TwinCAT I/O & OPC Server
• Microsoft Windows 2000 Server
• Microsoft Access
• Microsoft Excel
• Microsoft Netmeeting
• Lantronix Port Re-director

Client Comments: "This innovative system utilized fuzzy logic to control difficult temperature loops and gave us the tight control that our process demanded."

Chatham Project Manager