Wireless Comes Of Age

Feb. 1, 2008
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 opened, or a signal voltage has been applied to the inputs of some sort of transmitter or transponder. In other applications, a camera will transmit video data to a receiver, or a card reader will transmit a card number to an access controller.

Wireless devices have come down in cost, are increasingly compact and solve many problems. The technology keeps re-inventing itself.

One of the issues that initially slowed down deployment of wireless was power requirements of the transmitters. Large batteries kept wireless products in the “toy” or “gadget” category.

Battery technology improved dramatically .. Servo motors with small power requirements transformed the electromechanical lock industry. These developments brought portability and wireless operation closer to reality.

Telemetry continues to be an important part of the puzzle. Developments of radio equipment operating at higher frequencies are less vulnerable to traditional forms of interference. Using miniaturized circuitry opened the door further to dramatic new product developments.

I look at wireless as a way to avoid crawling in an attic or falling off a ladder. Whatever area of security you're involved in, you owe it to your clients and the profession to learn all you can and do the best job possible.

Digital processing and fabrication technologies are perhaps the Nexis of this entire world of advancements. When I was a kid, the transistor was the breakthrough that moved electronics away from vacuum tubes to the solid state. Logic was nothing new, but using it to create functional processes electronically was pretty new.

The next transition was the integrated circuit. Referred to as “small-scale integration” (SSI), improvements in technique has led to devices with hundreds of logic gates, referred to as large-scale integration (LSI). Current technology has moved far past this to today's Very Large Scale Integration (VLSI) which is the process of creating integrated circuits by combining thousands of transistor-based circuits into a single chip.

Microprocessors having many millions of gates and hundreds of millions of individual transistors are VLSI devices.

Remote Door Control is one of the more traditional applications for wireless electronics.

On two recent projects I required a wireless door control solution, and chose one of the more advanced products available for this application from LARCO.


Larco , a leading manufacturer of automatic door activation and safety products, has developed transmitters and receivers designed for compatibility with virtually all automatic door operators and control devices.

The ultra-small transmitters measure 1.25” x 0.875” x 0.25” and the receivers measure 2.25” x 1.25” x 0.75. Their size and excellent range makes it easy to locate the receiver inside the header, maintaining the clean architectural lines and reducing vandalism.

The units are factory pre-wired so installation is as easy as attaching the battery and pushing the programming buttons.

Larco's new transmitter and receiver units may be used with Larco's shallow profile universal wall switch and jamb switch box assemblies, or used for retrofit applications in conventional handicapped controls. When combined, these two new products become one of the smallest, most space efficient and most durable wireless automatic door control devices available.

The Larco Ultra-Small Transmitters and Receivers operate at 433.92 MHz (acceptable in the United States , Canada and any European Union member state) and employ code-hopping technology to reduce false activations.

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.