CAN bus standard evolves operator control module functionality

Since the dawn of space travel, around the time when OTTO was founded, control switches have played an integral part in providing the interface between the decision making capabilities of the operator and the response of the device being operated.

As times change and technology grows, our ability to integrate more functionality into singular devices is ever increasing. Key to this success is the Controller Area Network (CAN) bus standard. The large number of required inputs and corresponding outputs present many issues, not the least of which are the wire bundle size, routing and the integrity of the output signals. Through utilization of the CAN bus standards, engineers are able to incorporate a multitude of discrete inputs, controlling various functions via multiple operator inputs (i.e. control module, joystick, panel or grip).

Yet, while the technology drives the increased capabilities, the organization drives the project, and a structured value added infrastructure is now essential to succeed in this arena. This begins with a team of technical sales personnel who can translate the customer’s needs into a robust and complete technical document. An engineering team who is knowledgeable of the latest standards, protocols, software and interfaces. And finally, a complete and capable manufacturing environment that includes rapid prototyping, machining, molding, tooling, stamping, assembly and testing.

The CAN bus protocol was born in the early 1980’s. A viable version of the protocol was created by Bosch in 1983 which lead to the CAN network being used in the automobile industry for engine and braking control. It was further refined and adopted as the de-facto standard for networked communication in automobile manufacturing. The CAN communications protocol was embraced and utilized by the Society of Automotive Engineers (now known as SAE International) in the mid 1980’s in Detroit. The need to transmit large quantities of data simultaneously to and from a multitude of functional devices throughout the automobile required networking at an entirely new level, with an architecture that was fast, accurate and robust enough to work in the demanding environment, both under-hood and in the passenger areas.

CAN is a network of devices that utilizes a serial, message based communication protocol that is standardized in its handling of data. The CAN protocol is an international standard that is detailed in ISO 11898 and has a layered architecture in accordance with the Open System Interconnect (OSI) reference model. CAN has expanded into much more than the first format created by Bosch.

Today there is CANopen, CAN J1939, CAN Kingdom and home grown proprietary versions that have sub categories intended to serve particular markets, such as pressure sensors, agricultural and construction equipment, lift trucks, etc. The list continues to grow as the use of CAN becomes widespread throughout the world and as industries have embraced the value and capability of the CAN protocol. The common thread among all of the various CAN variants is the basic properties that provide the robust nature and flexibility of CAN.

The properties that provide the functionality are:

* Prioritization of messages

* Guarantee of latency times

* Configuration flexibility

* Multicast reception with time synchronization

* System wide data consistency

* Multimaster

* Error detection and error signaling

* Automatic retransmission of corrupted messages as soon as the bus is idle

* Distinction between temporary errors and permanent failures of notes and autonomous switching off of defects notes

As the automotive and electronics industries have pushed the advancement of technology, numerous CAN components have become available that are environmentally and electronically robust enough to handle the rigors of the construction, off road, agricultural and forestry fields. The new Operator Control Module from OTTO is a great example of a multi-use device with joystick and keypad functionality combined into one active assembly.

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Engineers and designers utilized an optimized product development process to develop this CAN driven device for a forestry tractor application. This particular forest tractor cab is like a command center on tracks and is loaded with individual components that must be networked together. The plug and play CAN environment allows the component suppliers to provide a value added service when developing new interfaces. The OEM can easily provide an interface document indicating the protocol to be followed along with the functionality of the accessory or control device. The component supplier can then provide a component that will plug in at the node in the CAN system that the OEM requires. All messaging, error handling and prioritization hierarchy is specified, guaranteeing that the unit will work as soon as it is plugged into the network.

As companies such as OTTO continue to show success in this arena, it only helps that the rapid product development infrastructure is clearly in place to create custom configurations and promote enduring success. While the engineers work on the components and interfaces, the machine shop can provide rapid prototypes of the conceptual product. This prototyping capability provides production-grade thermoplastic models from CAD designs that are accurate and repeatable.

By creating these custom configurations, a customer is able to evaluate the overall look and feel of a product within days, rather than the weeks or months it could take if a standard tooled and molded prototype is used. This gives the customer the opportunity to refine the ergonomics and design requirements and produce multiple prototypes prior to spending valuable dollars and time on standard tooling. Working these projects simultaneously completes the project in less time while assuring the quality and performance of the design. Rapid prototype development provides numerous advantages: a shortened development cycle, quality improvements by testing on site at each step of the project and ultimately, a reduction in the overall development and manufacturing cost.

While CAN technology has been around for a while, the applications continually grow to utilize this unique and effective protocol to combine a large number of components into smaller and smaller spaces. By leveraging a value added manufacturing program, one company can provide distinct, yet cohesive teams to design, manufacture and fully certify CAN solutions that allow for one stop new product development. The benefits are enormous; reducing the supplier base, minimizing the time to market and realizing measureable cost benefits by leveraging one consistent group of CAN experts from concept to completion.