"Key-in-Pocket" Digital Machine Safeguarding System

April 22, 2023
Digital maintenance safeguarding system from Pilz Automation protects against machine restart and tampering.

Preventing unauthorized machine restart, the digital "Key-in-Pocket" system is a flexible safeguarding device that ensures machines do not restart while maintenance work is being done and that unauthorized personnel do not gain access.


The system is based on the access permission system PITreader and is implemented using the configurable PNOZmulti 2 controller or the PSS 4000 automation system. Users are given an RFID key with their individual permissions, which can be read on the safety gate using PITreader. This way, users who are authorized for maintenance work can authenticate themselves. At all times, the operator knows who has access to which task. Temporary permissions can also be assigned.


A personalized security ID is stored for the user in the controller and is kept in a safe list. The machine can now be shut down, the safety gate opened, and the machine accessed. During this time, the RFID keys remain with the user. Once maintenance is complete and people have left the danger zone, everyone signs out. The security IDs are removed from the safe list on the Pilz controller, and the machine can be restarted.


Digital maintenance safeguarding is specifically designed for machines with danger zones that are protected via safety fences. It offers an alternative to mechanical lockout-tagout systems. “Key-in-pocket” offers more flexibility, more security, and traceability.

  • Authentication of persons, safe restart protection
  • Certifications: PL d Cat. 3 of EN ISO 13849-1, SIL CL 2 of EN 62061, and SIL 2 of IEC 61508
  • Full control over which person has access to which machine, temporary permission also possible
  • Simple to block, fast to reprogram when a transponder key is lost
  • Full traceability (can be deactivated)
  • Up to 20 people can access a machine at the same time
  • Manual reset function, “blind spot check” in accordance with EN ISO 13849-1 5.2.2.
  • Authorized personnel can delete the safe list
  • They do not need to exit the plant via the same door they used to enter
 Controller Reader UnitInput Device  Type 1PNOZ m B1 or PSS4000 PITreader Illuminated pushbutton Type 2PNOZ m B1 or PSS4000 PITgatebox with PITreader  PITgatebox with PITreader