Wireless limit switches generate own power

Paul Boughton

Balluff is introducing a means of connecting limit switches in inaccessible places where running cables is difficult or almost impossible - such as on gantries, lift and shift mechanisms and rotating machines.

Using wireless signal transmission eliminates the need for cables to be run to mechanical position switches.

At the heart of the system is the ability to generate power for signal transmission by utilising the energy from the action of the striker cam on the switch plunger, making any additional energy supply or battery completely unnecessary

The system comprises the proven Balluff BNS machine tool precision mechanical limit switch with transmitter, and an RF receiver module complete with antenna. The switch has a die-cast aluminium housing, viton seals with IP67 protection and maintenance-free telescoping plunger mechanism.

The receiver is DIN rail mounting for internal control panel installation while the antenna would usually be mounted on the panel top, although internal mounting is an option depending on site conditions. Transmission range is typically 30m in the production environment and 100m outside in free space using the license-free 868MHz operating frequency.

A single receiver can accept the signal from up to four switches; in addition a multi-network configuration is also possible where a single switch could transmit to more than one receiver. Integrity is guaranteed by the system protocol and by a 32-bit ID number for each switch station, giving 4.3billion transmitter combinations.

RF receiver features include a protected teach-in function, four volt-free relay outputs and indication LEDs for each channel.

For more information, visit www.balluff.co.uk