Industrial Controls and the Raspberry Pi

Industries with control equipment prefer to use a standardized system of mounting components such as circuit breakers within equipment racks. The most popular arrangement is the DIN rail and enclosure. The rails are typically made from a cold-rolled carbon steel sheet and zinc-plated or chromated for a bright surface finish. DIN is the acronym for Deutsches Institut fur Normung in Germany, and the rest of the world has adopted their standards as the EN and IEC standards.

The famous single board computer, the Raspberry Pi (RBPi) is becoming increasingly accepted as a development platform and a suitable solution for applications involving process controls. Some of these applications involve simple HVAC controls, power management, materials management, and gas detection, among a vast range. However, moving to the industrial arena means the RBPi needs to be fitted with a DIN rail enclosure.

That is exactly what VP Process Inc. has planned. Their series Pi-SPI-DIN of products, based on the RBPi, will all be DIN rail mountable, and hence, suitable for use in the industry. Their first product in the series is the RPi-3 controller, which will work from a wide range of input voltages between 9 and 24 VDC. It will provide RS485 Interface available on RJ45 connectors and Terminal Block. It will provide the RBPi with a real-time clock and battery backup with a CR2032 battery. The user will be able to make use of all the GPIO interfaces of the RBPi as they will be available on a 16/24 pin ribbon cable connector. The DIN rail enclosure will have LED indicators, and VP Process Inc. will be offering sample test programs in C and Python. The idea behind developing the RPi-3 is to allow the RS485 interface to communicate with all the eight channel modules available from VP Process Inc.

The first of the new series from VP Process Inc. is the PI-SPI-DIN-RTC-RS485, and this will be available with DIN rail mounting hardened interfaces in three mounting versions—with DIN rail clips, DIN rail enclosures, and PCB spacers.

The wide-ranging power input accepting any voltage between 9 and 24 VDC of the unit will produce an output of 5 VDC at a maximum current of 3 Amps. There will be two GPIO connectors, one belonging to the RBPi board, and the other is external for peripherals. Another 16-pin connector will provide the power, SPI, I2C, and five chip-enables for the PI-SPI-DIN series.

Apart from the RS485 interface, VP Process Inc. is planning for other peripheral units as well. These will include the eight-channel 4-20 mA module, four-channel relay output module with contacts rated for 2 Amps, eight-channel isolated digital input module, and four-channel 4-20 mA module.

VP Process Inc. will be providing each module with two 16-pin ribbon cable sockets and cables. Each of the connectors and cables will carry the main power supply input to the main interface, SPI bus, I2C bus, and the five GPIO lines serving as chip-selects.

To maintain compatibility with non-industrial uses, VP Process Inc. will also provide each peripheral as a PCB on spacers, apart from PCB with DIN rail enclosure or DIN rail clips.