iSensor Volt Free Contact (VFC) for iSensor & iAccess Controllers

The iSensor Volt-Free Contact (VFC) is a simple, reliable sensor that functions as a voltage-independent, mechanical switch. Unlike a traditional switch, it does not generate electrical power. Instead, this smart device makes it easy to share information. It sends updates about whether circuits are open or closed. This information goes straight to your IT, facility, or data centre systems. It uses standard communication methods that all these systems understand.

Our “dry contact” design solves a common problem. It stops voltage differences from causing issues. This means you can easily connect it to your existing systems. It works with management platforms like NMS, BMS, and DCIM.

The VFC connects to an iSensor or iAccess controller with a standard CAT 5/6 Ethernet cable. You can use cable runs up to 500 metres, which gives you plenty of installation options. The device uses a basic mechanical switching action. When a door opens, a panel triggers, or a linked system changes state, the contact either closes or opens. The controller reads this change and sends the event to your chosen platform.

You can set the device as Normally Open (NO) or Normally Closed (NC). This helps you match the sensor to different operational needs. The VFC also includes a 100ms anti-bounce time. This short delay stops rapid flickering of the switch from creating false alerts.

The VFC gives you a safe and isolated connection point. Because the contact is “volt-free,” it never introduces voltage into a circuit. You supply the voltage that drives the signal. This protects your systems from electrical conflicts and makes the VFC suitable for a wide range of equipment. Many teams choose dry contacts because they reduce risk, keep wiring simple and help avoid interference between systems.

Data centres rely on accurate and fast signalling. The VFC sensor supports this by keeping its design simple and robust. It uses an RS485 interface at 9600 baud rate, with an 8 data-bits, 1 stop bit, no parity configuration. This keeps communication stable and predictable. The device also runs on very low power: 5 V DC at 100 mA, with an internal 3.3 V supply that draws only 50 mA. This reduces heat, keeps energy use low and helps ensure long-term reliability.

Facility teams often use the VFC sensors to track door contacts, security panels, equipment alarms, airflow switches, power events and many other binary signals. Because the device offers complete electrical isolation, it suits almost any system that outputs an open/close contact. You can also integrate it into safety systems, interlocks, threshold triggers or backup equipment.