Software verifies machines’ functional safety


Discrete Control

The Pilz PAScal Safety Calculator helps save time and money by easing computation of failure limit values.

A Pilz software tool helps verify machinery’s functional safety based upon current standards. PAScal Safety Calculator supports manufacturers in the calculation of failure limit values, as required by standards IEC 62061 and prEN ISO 13849-1.


The software tool enables a reduction in cost and time spent on the task, particularly as figures need to be recalculated each time the safety functions are modified. It separates safety functions into component parts, calculates the overall hourly probability of a dangerous failure (PFHD value), and verifies data with the prescribed performance level or safety integrity level.


It accounts for potential architectures and variations if sub-components connected and parameterized. IEC 62061 (sector standard from IEC 61508 for safety in machine control systems) says safety-related functions are divided into sub-systems, such as sensors, inputs, logic, outputs, and actuators. Architecture for each sub-system can be specified separately. Sub-systems can be combined as required. It considers factors listed in prEN ISO 13849-1 for evaluating the common cause failure (CCF) accounts for parameters that depend on logic or electronics, which affect diagnostic coverage (DC). Examples include detection of shorts between contacts or synchronicity monitoring on multi-channel sensors.

—Edited by Mark T. Hoske, editor-in-chief, Control Engineering

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