FailSafe Servo Safety for All

Summary

It's no secret that safety is paramount in automated systems. Without adequate safety measures in place, operators can be at significant physical risk. Fortunately, functional safety systems help mitigate or remove potential safety concerns. They keep the system safer by monitoring the components, controlling output, interrupting power in emergency situations and much more. As industries become more automated, agile and complex, safety systems must be kept in step.

Before the evolution of network-integrated safety, functional safety systems were hardwired, and typically made of non-OEM components. With safety signals traveling over a network, Fail Safe over EtherCAT (FSoE) eliminates wiring between sensors like door switches and light curtains to a safety relay, safety controller, or safety Programmable Logic Controller (PLC). Implementing functional safety with FSoE can simplify input wiring, eliminate output wiring to servo and variable-frequency drives and reduce the number of safety controls needed on a large machine. Being easier to implement and more capable than hardwired functional safety systems, FSoE provides automation engineers with a wider array of methods to mitigate risks to people.

Now, with FSoE you can have safety and non-safety command traffic on a single network. There is no need for a secondary, hardwired system dedicated solely to safety sub-functions.
 

Better, safer, more capable

When triggered by external switches such as an E-Stop button, gate switch, or light curtain sensors, the Safety CPU instantaneously utilizes the programmed safety sub-function response. The command is then sent to the servo amplifier, which executes the safety sub-function. Depending on the situation, this could be actions like stopping power to a component for an uncontrolled stop, slowing it down to a safe speed, or limiting the motion of the servo so it rests in a safe position. These immediate actions protect both the components and the operators.

Imagine an operator needing to get a closer view of part of the production line, but the nearest protective enclosure doesn't allow the sight line necessary to that assembly process. To address this sight-line issue, the production line was designed with a light curtain area so operators could gain access to a better vantage point. There the operator can safely approach the assembly line. When the light curtain sensors are tripped, FSoE responds automatically. It also recognizes the operator's proximity to the line. A hardwired system might execute a Safe Torque Off to cut power, bringing the line to a stop. Instead, FSoE sends a Safe Operating Stop command, slowing the motors in that area only.

As the operator gets even closer to the line, FSoE executes a Safe Stop, further slowing the motors to a halt. While the operator remains in the light curtain area, power still flows to the motor instead of being cut. When the operator exits, the motors come back up to speed much faster than if they had to power back from a dead stop. FSoE-compatible servo amplifiers protect machine operators. This gives machine builders the ability to increase the efficiency of a safety-enabled machine without compromising the overall desired safety level.