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Nano-PLCs offer remote control via 3G networks

17 July, 2014

The French automation manufacturer Crouzet has announced a range of nano-PLCs that includes models designed to connect to the Internet via 2G, 3G or Ethernet. The em4 PLCs, which can be controlled remotely, are the same size as Crouzet’s Millenium 3 logic controllers, but have twice the memory capacity and cycle times that are up to five times faster.

The nano-PLCs, based on 32-bit processors, come in three versions. The flagship “remote” models are designed for connection to the Internet, allowing remote programming, monitoring, control and datalogging of single machines or fleets of machines. They can connect to the Internet on demand using 2G or 3G SIMs, or Ethernet cables, without needing any extra modules.

The PLCs do not have embedded Web servers but use machine-to-machine connections instead. Raw data is exchanged between the controller and a dedicated server. This is said to optimise communications and prioritises the server’s memory space over the em4’s embedded memory.

The “alert” versions are capable of sending SMS or e-mail alerts, while the simplest “local” versions do not support remote communications, but can be connected to a local network.

Allied to the control hardware is the “em4 lab” software environment which includes programming software that uses application-specific function blocks said to make programming easy. Communications can be programmed graphically using the same software, which is compatible with the M3 Soft package for Crouzet’s Millenium 3 controllers. Programs created using M3 Soft can be read and translated for the new hardware.

Applications running on em4 PLCs can be accessed via a Web browser, and there is also an em4 app that allows access from smartphones for simple local or remote control, or event management.

Crouzet's em4 nano-PLCs are available in a choice of white or black liveries

The expandable controllers have at least 26 I/O, including direct inputs for precision sensors outputting 0–20 or 4–20mA. These inputs are said to avoid measurement errors as well as providing 1% measurement accuracies. There are four configurable digital inputs, 12 digital/analogue outputs, two PWM outputs and eight relay outputs (two at 6A and six at 8A). The controllers, which are available in white or black enclosures, incorporate four-line, 18-character displays.

Crouzet has established a “partners community” which will provide applications with extra functions using peripheral components supplied by partner companies. The community could also provide extra services such as remote management or customised smartphone applications.

Crouzet developed the nano-PLCs with backing from the French government under a collaborative programme designed to link the worlds of automation, telecoms and networking for machine-builders. The em4 controller is the first stage in this project.

Crouzet is part of CST business that was previously owned by Schneider Electric. In May 2014, the business was acquired by the Carlyle Group in a deal valuing CST at around $900m.

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