How ifm efector is taking PLCs from fail-safe to mine safe

Ifm efector is placing safety front-and-centre with its latest programmable logic controller (PLC). Safe to Work speaks to ifm’s Freddie Coertze.

German sensor specialist ifm efector is no stranger to safety concerns. As the first company to invent the proximity switch, ifm evolved from family-owned beginnings to full safety systems.

Many of its products are used to maintain safe monitoring in industrial, materials handling and processing contexts. Over the last 18 months, the company has developed a SIL3-compliant programmable logic controller (PLC) called SafeLine SmartPLC that integrates both fail-safe and standard PLCs into one system to streamline processes.

The fail-safe and standard PLCs are designed to communicate harmoniously so that standard processes and safety processes can be integrated into one unit.

A visualisation system is included to offer programmable web visualisations via an internet browser. The system also includes a graphic display for easy access to important information.

One side uses an AS-i (actuator sensor interface) gateway for device connection and the other side has compatibility with Profinet, Profibus and EtherNet/IP.

According to ifm product manager of industrial communications Freddie Coertze, SmartPLC’s versatility makes it particularly well suited to conveyor applications in mining. For example, it can be applied to a conveyor’s safety pull cord system for emergency stops.

“What we’ve done with conveyors in the mining industry is take a two-wire cable that can run right along the length of a conveyor and safety equipment such as safety ropes, kill switches, and lanyards etc. SmartPLC has a chip built into it that can simply clip onto the standard bus system,” he explains.

“Imagine if you have a really long 1.2km overland conveyor — you just run those cables wherever you have the need for a safety device. You clip on the BUS system, and then you have a safety device there — it’s really flexible and saves time and wiring.”

ifm's SafeLine SmartPLC offers an integrated solution.
ifm’s SafeLine SmartPLC offers an integrated solution.
ifm's SafeLine SmartPLC offers an integrated solution.
ifm’s SafeLine SmartPLC offers an integrated solution.

The safety module of the SmartPLC contains two printed circuit boards (PCBs) that each use separate voltage supplies but are connected via an interface so they are able to exchange data.

One of the PCBs harbours twin processors for signal processing, and the other is designed for I/O (input/output) operations.

Through use of a data logger, the PLC’s system data can be recorded and stored on an SD card or in the system’s flash memory; and data blocks can be time stamped via an integrated real-time clock for easier documentation.

The SD cards can also be used to copy device configurations to another device (a process called ‘cloning’), which saves further time and effort.

ifm emphasises a balanced approach to safety systems, maintaining an efficient balance of productivity and safety. The SmartPLC device is designed so that a single fault won’t necessarily bring systems to a halt.

“You’ve got to find a happy medium,” explains Coertze.

“How does the safety system affect the downtime of my machines? How does it affect the operator’s work? It used to be that you had to wire up everything, whereas now it’s all communicated over a two-wire system.

“If you think of it as if it’s your house it’s almost like an extension cord. You’ve got one power point using multiple adapters that you just plug all your stuff in — it’s easier than just wiring everything back to one panel or one system in that respect.”

It is a design philosophy that extends beyond the SmartPLC to other ifm products, such as its magnetically coded actuators (for non-contact door monitoring) and tamper-proof RFID sensors.

This helps to keep doors closed, preventing entry to potentially unsafe work areas and generally improving security over mechanical lock systems.

The company’s products go through a number of stringent tests before being shipped to ensure safe operation. This includes stress testing in specially designed cubicles that can “age the products by about 25 years in 28 weeks,” according to Coertze.

When being stress tested, products are placed in environments where humidity is turned up. Components endure temperature fluctuations, static testing (interference from other sources) and flammable environments.

“All of our sensors go through quality testing,” Coertze says. “We are one of the only companies that actually provides a five-year warranty on all products.”

This article also appears in the Oct–Dec edition of Safe to Work.

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