Wireless Comes Of Age

Larco has developed transmitters and receivers designed for compatibility with virtually all automatic door operators and control devices.


The term wireless is liberally applied to all type of technology these days. It broadly describes the means by which a signal or data gets from a point to another or to many other points. For example, some wireless devices report status to a receiver, like a button is pressed, or a door is...


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The receiver only operates after learning a transmitter's signal through the simple programming procedure which eliminates the need to set dip switches and involves a simple press of the programming button located on the top cover of the receiver.

The receiver comes equipped with a wiring harness for easy installation and servicing. When the receiver is activated, its outputs will stay in the minimum activation state for approximately 1.5 seconds (default). This time can be adjusted to stay in the activation state for up to 4 hours.

The first application was the adding of a handicapped button and remote door operator control to a library reference room door, requested only after the entire library construction process was completed.

The customer wanted a couple of capabilities added to a pair of doors which were equipped with a LENEL card reader, Von Duprin EL surface-mounted vertical rods and a pair of DORMA ED800 low energy door operators.

These doors controlled entry and egress from the library's reading room. Students and academics passed in and of the area all day long, sometimes with valuable manuscripts and other study materials. The librarians needed the ability to remotely open the doors for individuals attempting to pass through the opening so the individuals would not be required to press a button, pull or push open the doors, and possibly dropping the valuable materials. Additionally, a handicapped button for egress was required by ADA .

By using a LARCO Wireless Handicap Button, pendant transmitter and receiver, all these functions were fulfilled with a minimum of labor and expense to the library.

The second application involved the control of a door operators on another school. These outer and inner exterior vestibule doors had single door hydraulic operators on one leaf of each pair. The doors were set up in a non-sequenced mode, and I was instructed to not change that. What needed to be changed was the operational mode of the doors.

All exterior doors were equipped with EL exit devices so the building could be locked down electronically from a central location. However, the original handicapped wireless transmitters were not working reliably, and were not encrypted, sending the same 8-bit code based on the pattern set on the DIP switches. Once the ELs were locked, pressing the exterior entry button caused the door operators to try to open the locked door.

A four channel Larco receiver, and four Larco transmitters were installed to modify the system. Transmitters were installed in each of the handicapped buttons. The receiver was connected to the door operator's trigger inputs.

Only three channels of the receiver were used. Channel one handled both of the handicapped buttons for the inner door, since that door operator did not have any rules.

Channel two was used for the egress handicapped button for the outer door. This door might be locked when someone was attempting to use the handicapped feature. But because the hydraulic door operator has an integral delay between when it is triggered and when it actually starts to move the door open, no additional electronics were needed to sequence the signal.

Channel three was connected to the outer door operator input through the NO (normally closed) dry contacts of a slave relay whose coil was connected across the voltage input to the Von Duprin EL module. When power was applied to the VonDuprin EL, it was unlocked, and it was OK to let the trigger pulse through to the door operator. If the EL was not getting power, it was locked, and the relay blocked the trigger pulse to the operator.

For more information, contact your locksmith distributor or Larco Manufacturing, Phone: 218-829-9797 or 800-523-6996. Web site www.larcomfg.com.   

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