The PROTECT PSC safety controller, which the Schmersal Group presented a few months ago, distinguishes – amongst other things – by its completely modular system structure. Depending on the requirements, the user can combine different modules, which can be smoothly fitted onto DIN rails and interconnected through a Backplane Bus. The electronic safety system is now further extended: Elan - within the Schmersal Group the Centre of Competence for safety-related control systems – presents the PDMS, which is short for Protect Drive Monitoring System.

This system enables the machine builder monitoring the speed of, for instance, spindle or axle drives in a safe manner. To detect the movement, encoders, resolvers or two proximity switches can be used. The system monitors the signals from rotary and linear movements. The drive speed to be monitored can be individually programmed.

In this way, the maximum speeds for the special operating modes of, for instance NC machining centres, e.g. operating mode 1 (“automatic mode”), operating mode 2 (“set-up mode”), operating mode 3 (“process monitoring with enabling device”) and operating mode 4 (“process monitoring without enabling device”), can be individually set and safely monitored in accordance with DIN EN 13128 4.

Similar to PROTECT PSC, the functional components of PDMS are based on a modular system. The monitoring electronics, which is connected to the signal generator signal through a drive-specific cable adapter, is located on an input card. Every axle is monitored by means of its proper pluggable input card. Inside the system rack, multiple and even different cards can be combined. Safe output cards transmit the signal to PROTECT PSC, where they are further processed. Appropriate cable adapters are available for a multitude of drive systems.

The PDMS system extends and completes the features of the modular PROTECT PSC safety system with monitoring functions for machinery and plants. The system meets all the requirements set forth for safety-related electronic components. The self-monitoring circuitry has a redundant structure, which means that the safety device remains safe, even in case of failure of a component.

The machine builder therefore has a flexible and individually programmable system for the safe monitoring of drives at his disposal. This system not only increases the safety, but also enhances the productivity of the machine concerned: the PDMS only transmits the enabling signal for the safety guard when the dangerous movement has come to standstill or at least has slowed down to such extent that the movement no longer involves any risk. In case of time-controlled monitoring, a specific time buffer must be provided, so that the safety guard is enabled at a later time.