Process Monitoring and Control

Harsh environments require robust systems. Manufacturing environments and control and monitoring tasks often require continuous operation for long periods with little or no maintenance. An electronic control system may need to be protected against temperature extremes, ingress of dust or water, condensation, vandalism, EMI, noisy power supplies or vibration.

Industrial control system

In order to provide a suitable environment for microprocessor based systems, particularly those with complex transducers and analogue signal conditioning, Design Interface Ltd has developed enclosures which employ:

process control Ducted ventilation
embedded system design Air conditioning
process monitoring Heat exchangers
microcontroller based systems Solid state (Peltier) temperature control
electronics design consultants Sealing to IP65 standard
industrial control Potting
microprocessor system designers Screening
electronics engineers Line conditioning
process control Uninterruptable power supplies

In addition to monitoring some external process the system should be capable of monitoring itself and raising an alarm if, for instance, the protected internal environment is compromised in some way.

In industrial applications we have long advocated the 'intelligent' factory model where distributed monitoring and control nodes are linked through a 'Field Bus' network. Process information can then be viewed and stored remotely and data dependent alarm conditions can be defined.

PC104 based system

This system controller uses a PC104 based PC (not fitted in this image) mounted on a motherboard which provides all of the required digital and analogue I/O. An FPGA offloads some of the low level monitoring from the PC and provides: bus decode logic; timers; counters; interfaces and safety interlocks.

Analogue interface board

Standalone controllers can often be economically produced simply by providing an industrial PC with the necessary analogue I/O conversion hardware. This board uses a number of serial analogue to digital and digital to analogue converters and continuously scans them such that they appear as a bank of parallel registers to the PC.

Class D power supply for Peltier devices

Simpler controllers such as this Class D H-bridge driver for Peltier devices are completely self contained. A PWM controller is interfaced to a thermocouple and a bidirectional driver to provide closed loop temperature control of a specialised camera to within a few tenths of a degree centigrade.