Pixel Turns Five

Details of EC’s elevator control system are revealed in this Product Spotlight.

This summer marks the fifth anniversary of the introduction of the Pixel Elevator Control System from Elevator Controls Corp. (EC), headquartered in Sacramento, California. Pixel has matured over these years, expanding both its feature set and applicability to cover a wide spectrum of applications.

History

The vision and concept for the Pixel were conceived in 2009, when a development effort to create a new control-system platform for manufacturing was launched. The design and functional requirements for the product were established with industry experience, input from EC’s diverse customer base and available new technologies. Over the following three years, prototypes were built, and validation sites were identified for testing. Full-scale production was launched in 2012.

Pixel for AC applications was implemented first (geared, then gearless), followed by Pixel for DC applications (geared and gearless). Pixel was developed with a level of design sophistication to support a wide variety of applications, device interfaces and features, allowing it to be applied to the most complex building applications that premium control systems must support.

EC was then faced with a question: “What should be done for hydraulic applications?” Pixel is a sophisticated controller, but was the answer to design a different controller for hydraulic applications?

Strategy

EC’s long-established corporate strategy provided the answer to its question. The “Know One, Know All” philosophy that has guided product development over EC’s 30-year history remained applicable, leading to the answer that Pixel would be applied to hydraulic applications, as well. The result of this strategy, carried out through Pixel’s product design, is a product platform that promotes quality and efficiency through consistency and repetition. These gains are realized in both manufacturing quality and efficiency, and in field-installation quality and efficiency.

Installation and maintenance experiences are consistent across Pixel installation sites, whether it be a three-stop hydraulic; machine-room-less; or high-speed, high-rise elevator driven by a gearless machine. Configuration and adjustment of Pixel systems are accomplished through the same user interface in all applications, and the list of circuit boards required to maintain Pixels for all types of elevators is minimal, because the circuit boards are common to all Pixel control applications.

Fundamental Advantages

Fundamental advantages gained with Pixel include:

• The form factor of Pixel controllers is the same for all types of applications. The repeatability in manufacturing enhances build quality and efficiency.
• Pixel users enjoy a higher level of effectiveness and efficiency because of the consistent form factor. There is no need to learn how to install and adjust different control systems for different applications.
• The cost of support and stocking of spare parts is minimized with Pixel. A small collection of components will support all Pixel controllers, even if there are many different types of Pixel controllers in the service portfolio.

Product Design Concepts

While a consistent product platform offers important advantages, equally important is the design of the product platform. Some fundamental design features and design concepts that make the Pixel effective and efficient follow.

Access to Information

Pixel’s design minimizes the use of hardware components and makes use of microprocessors and serial data communications. Much of the logic that operates the elevator is handled in software, and most signals are transmitted between microprocessors over data communication lines. As a result, much of the information that historically could be checked with a multimeter is no longer accessible with one. To address this inherent issue, Pixel systems offer built-in advanced configuration and diagnostic stations, located in the three main locations where most of the work is done: the controller, the car top and inside the cab. Thus, there is little need to walk back to the machine room to get information, further enhancing efficiency and personnel safety.

Information is presented through color graphic screens accessed in an efficient and intuitive manner. A rotary knob is used to highlight and select menu items, and four “soft keys” are used to execute commands or configure parameters. Pixel also provides “Home” and “Help” buttons, making navigation and troubleshooting easy. The graphic screens provide increased information presented using descriptive language and allows for advanced event data logging and recording of information for troubleshooting. All configuration and troubleshooting can be done without external devices. A built-in USB port is provided for downloading product configuration and diagnostic files to a flash drive, and software upgrades for the entire Pixel system can be done from the machine room, also using a flash drive, with files downloaded from EC’s website.

Application of Serial Data Communications

The appropriate use of serial data communications in Pixel’s design serves to minimize wire count and wire lengths. Reducing total wire length reduces cost, and having fewer wires running adjacent to each other reduces the possibility of induced electrical noise between them. Reducing the total wire count (and, therefore, the total number of connections) reduces the opportunity for wiring mistakes. Keeping device connections “local” (e.g., car-station device connections are made to a board mounted in the car station) also allows for work to be done in advance, in environments that promote quality and efficiency.

With Pixel, for example, car stations can be prewired and pretested on a work bench, which is more efficient than making those connections in the elevator cab. Pixel engineers chose to design CAN bus technology into the Pixel product because of its reliability and robustness, and because it allows for interoperability as more manufacturers incorporate CAN bus technology into their product offerings. All safety-critical signals are wired directly to redundant safety processors, minimizing signal propagation delays and eliminating the dependency on serial data communications for the delivery of these critical signals.

Encoded Car-Positioning System

In contrast to traditional perforated tape or follower-wheel systems, Pixel’s Landa car-positioning system is encoded. It does not use an “incremental” position-sensing method and precludes the need to count holes in a tape or count pulses from an encoder. Landa’s dual sensor system, mounted on the elevator cab, reads a position value from an encoded stainless-steel tape, requiring no car movement or car-position calibration process to reestablish the car’s position in the hoistway when power is cycled. Landa’s encoded tape provides unique position values throughout the entire hoistway with an accuracy of 0.8 mm.

With Landa, there are no door-zone magnets or floor encoding magnets to apply to the tape, and Pixel requires no terminal-landing slowdown switches (only the code-mandated final limit switches are required for traction elevators). During installation, the location of a floor is quickly defined by moving the car to a floor and pressing the “Learn” button on a user-interface station. Since it takes only a few seconds to do this, the floor locations for a 20-landing building can be defined in less than 1 hr., compared to the time it would take to mount 20 floors’ worth of door-zone magnets. Once installed, Landa is maintenance free. There are no tape guides to wear (and replace), and floor-level adjustments are made through Pixel’s configuration user interface. Once installed, there is no reason to return to the car top to make adjustments.

What You Get

As the Pixel is a complete system (not just a controller), much of what is needed to install the control system is included when delivery of a system is taken. The following is included with each Pixel:

• The Pixel main controller
• The Landa car-positioning system, which includes a dual sensor unit assembly, encoded stainless-steel tape and mounting brackets for both the car-top sensor assembly and stainless-steel encoded tape.
• A Pixel car-top processor box with traveler conductor terminals, prewired car-top inspection station, prewired work light with switch, prewired ground-fault-circuit-interrupter outlet and mounting brackets for the car-top box.
• Network circuit boards for local connection of car-station devices: these are usually pre-mounted, prewired and fully tested by the car-station manufacturer.
• A custom-labeled wiring harness to connect the car-station signals to the car-top processor box: the connections are efficient with Pixel’s custom-labeled wiring harness. Because the individual conductors in the harness are labeled with Pixel terminal designations, there is no need to create a wiring pull sheet.
• Network circuit boards for local connection of hall call buttons, hall arrival lanterns, fire-recall switches, hoistway-access switches and other devices
• A hall network wiring package, which includes cables and network splitters for plug-and-play hall network connections
• An optional custom-labeled travel cable: for most passenger elevators, the custom-labeled Pixel travel cable makes installation efficient. The individual conductors in the travel cable are labeled with Pixel terminal designations, making wiring easy. (Once again, there is no need to create a wiring pull sheet.) The number of travel-cable conductors is kept at a safe minimum, further reducing installation time and opportunity for error. (Most Pixel controllers use 22 or fewer travel-cable conductors.)

Pixel’s total system design allows for the elimination of many devices normally associated with the operation of an elevator, and it includes more of the components needed to proceed with and complete the installation. With the added items provided with every system, the Pixel package reduces the need to source parts from other vendors and allows installation to commence immediately.

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