Signal conditioners make their own decisions

A Tewkesbury company has developed a signal conditioning system that can be programmed to perform decision-making on board, often avoiding the need for a separate PLC. Status Instruments has spent three years developing the DIN-rail-mounting Medacs 2000 modules which accept inputs from a wide range of sensors, and can communicate with higher-level plant controls via bus systems.

Embedded in each Medacs is "transfer function module library", or TFML, which performs routines such as PID control, maximum and minimum datalogging, and tank linearisation.

Status is building up a library of these routines which users will be able to download free of charge from its Web site. Alternatively, users can develop their own routines (using the Forth language) or commission Status to develop routines for them.

Managing director Brian Turner predicts that the TFML capabilities will open up new applications for signal conditioners. "We expect to be dragged into areas we haven`t dreamed of yet," he says.

The modules also support OPC (OLE for Process Control) which means that they should connect seamlessly with other OPC-compliant systems, such as HMIs or SCADA packages. Each module has an RS485 interface, allowing data to be sent to and from other system using the Modbus protocol. Gateway modules are available for other buses including Ethernet and Profibus.

The signal conditioners are available in either single- or dual-channel versions. Neighbouring modules can be interconnected simply by attaching a clip-on "bus jumper" between them. Outputs include an isolated 4-20mA retransmission signal, a single changeover trip relay, and dual normally-open relays.