Process interlocks
Process interlocks prevent production downtime
Magnetic interlocks are used as process interlocks and prevent process disruptions in machines without run-down time. They keep a door or guard closed as long as the magnet is energised. Depending on the model, a holding force of 600 N or 1200 N is available.
For safety applications, these process interlocks can be equipped with an integrated safety sensor, enabling compliance with PL d according to EN/ISO 13849-1. Series connection with OSSD is also possible, providing additional flexibility and safety in the installation.
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Process locks with RFID and Bluetooth
HoldX process locks are an intelligent magnet lock and RFID safety switch combined into one product with a single connection.
Easily place up to 30 process interlocks in daisy chain without losing the safety function and retaining diagnostic data for each interlock (using OSSD contacts).
Further connecting of the wiring of the switch can be done quickly and easily with the double pigtail connection.
HoldX process locks are equipped with Bluetooth so that the diagnosis can be easily performed via the free App or desktop software.
Holdx smart magnetic lock with diagnosis
Holdx RS compact process interlock
The HoldX RS is a magnetic process lock that is equipped with a contactless safety switch with transponder technology (RFID).
This makes the Holdx RS suitable for use in SIL2 (EN / IEC 62061), Category 3 (EN 954-1) and PLd (EN / ISO 13849-1) applications. The holding force of the magnet has a maximum of 600N.
- Magnetic lock with 600N holding force.
- Extremely durable and wear-resistant.
- Built-in (uniquely) coded RFID safety sensor.
- The unique coded variant is also rechargeable.
- Optionally equipped with a permanent magnet that prevents accidental opening of the door.
- The permanent holding force can be set between 0-50N via the free Bluetooth app or desktop software.
- The magnetic flux is continuously measured to detect contamination on the magnet.
- Great alignment tolerance.
- Daisy-chain up to 30 locks without loss of safety (by OSSD contacts).
- Equipped with status diagnosis by LEDs. and Bluetooth.
- Anchor plate with alignment option.
- Response time of 75ms.
- 8pin M12 plug connection with Pigtail cable.
- Can be used as a highly coded switch according to EN ISO 14119: 2013.
Up to 30 interlocks in
daisy-chain
HoldX magnetic locks can be fitted with 2 pigtail plug connections for easy daisy-chaining on machines with multiple access points.
Because the HoldX has built-in OSSD contacts, it is possible to put up to 30 magnetic locks in daisy-chain without loss of safety.
Prevent process disruption
Process Interlocks are the ideal solution for locking doors and hatches that allow access to moving machines with little or no run-down time.
Because the magnet is continuously energized the safety interlock can only be opened after an access request. Opening the process interlock then gives a signal about the safety circuit to the safety controller.
Reaction time
A big advantage of the HoldX process lock is the very short response time of 75 ms. This makes it possible to place the safety device closer to the machine.
Compared to many other common process interlocks on the market (with a response time of 260 ms), the safety distance can be limited by almost 30cm (assuming they have the same run-out time).
Holdx RL heavy duty process interlock
The HoldX RL magnetic process lock is in all aspects the same as the Holdx RS but with an electromagnet that has a holding force of no less than 1200N.
- Magnetic lock with 1200N holding force.
- Extremely durable and wear-resistant.
- Built-in (uniquely) coded RFID safety sensor.
- The unique coded variant is also rechargeable.
- Optionally equipped with a permanent magnet that prevents accidental opening of the door.
- The permanent holding force can be set between 0-50N via the free Bluetooth app or desktop software.
- The magnetic flux is continuously measured to detect contamination on the magnet.
- Great alignment tolerance.
- Daisy-chain up to 30 locks without loss of safety (by OSSD contacts).
- Equipped with status diagnosis by LEDs. and Bluetooth.
- Anchor plate with alignment option.
- Response time of 75ms.
- 8pin M12 plug connection with Pigtail cable.
- Can be used as a highly coded switch according to EN ISO 14119: 2013.
Frequently asked questions about process interlocks
A process interlock is used to keep a machine guard, door, or hatch closed during operation to prevent unwanted interruption of the production process. Magnetic process interlocks such as HoldX combine a holding magnet with a safety sensor where safety monitoring is required.
The key distinction is the purpose of the locking function. Process locking is primarily intended to prevent unwanted process interruption, particularly on machines with little or no run-down time. Where a guard must remain locked because a hazardous machine condition persists after a stop command, the locking function must be selected and validated for that safety requirement. EN ISO 14119 is the principal standard covering interlocking devices associated with guards.
Process interlocks are particularly suitable for doors and hatches on machines with little or no run-down time, where opening a guard unnecessarily would interrupt production. An access request can first stop the process before the magnetic lock is released.
Required holding force depends on the guard design, expected forces, installation, and application. For example, the HoldX range provides 600 N with the compact RS version and 1200 N with the heavy-duty RL version. Holding force should therefore be selected from the application’s mechanical requirements rather than simply choosing the highest available value.
Yes, depending on the device architecture. HoldX process interlocks use OSSD outputs and can be connected in a daisy chain. Unique Safety Products states that up to 30 HoldX interlocks can be connected while retaining the safety function and individual diagnostic information.
Modern process interlocks can provide considerably more information than a basic door-open/door-closed signal. HoldX provides LED and Bluetooth diagnostics, while monitoring magnetic flux can help identify contamination affecting the magnet. Diagnostic information can support troubleshooting and preventative maintenance.
For EU/EEA machine-safety applications, relevant standards can include EN ISO 14119 for interlocking devices associated with guards, EN ISO 13849-1 for safety-related parts of control systems, and EN IEC 62061 where functional safety is designed using that standard. The required PL or SIL must come from the machine’s risk assessment and safety-function design rather than from the interlock alone.
For the HoldX RS and RL specifically, Unique Safety Products states PL d according to EN ISO 13849-1, SIL 2 according to EN IEC 62061, and that the devices can be used as highly coded switches according to EN ISO 14119:2013.
