Electrical systems are becoming more complex with each new series of agricultural, forestry, and construction equipment. Producers have benefited from these systems by applying them to precision agriculture applications and improved machine failure diagnostics. Incorporating Global Positioning System

(GPS) receivers with these new electrical systems has allowed for site-specific data collection and precise product application. Implements have also seen a recent increase in electronic components. Many implement operations and adjustments are now controlled remotely from the tractor by way of electronic signals.

[FIGURE 1 OMITTED]

While this increase in electronics has led to advanced data collection and more precise control of agricultural operations, it has also ushered in issues concerning compatibility between competitor products. To date, electronic components have little compatibility, which leads to a growing number of "black boxes" in the tractor cab. Not only do the control boxes reduce visibility from the tractor cab, but multiple in-cab monitors distract the operator from the operation at hand.

Over the past 13 years, several groups have made great strides in standardizing the method by which electronic signals are transferred within agricultural vehicles and thus eliminate the need for operation-specific control boxes. This standardization is very similar to work performed in the mid-1970s to unify the types of hydraulic connectors used in agriculture. The benefits of standard equipment electronics are numerous, including: greater compatibility among competitor precision agriculture products, interchangeability between sensors and field operation controllers, enhanced equipment performance and maintenance records, and improved diagnostics to reduce equipment downtime.

Standard progress

A major portion of the standard for agricultural vehicle communications has been published as International Standards Organization (ISO) standard 11783, commonly called ISOBUS. The basic portions include sections on physical wiring and means of communication. Essentially, this defines the language in which each electronic device will communicate. Efforts have been made to develop ISO 11783 to be compatible with Society of Automotive Engineers (SAE) Standard J1939, which focuses on vehicle communication in large trucks and off-road equipment and has been successfully implemented for many years.

One of the main advantages of the ISOBUS standard is that it uses a controller area network (CAN) to transfer data between multiple points on agricultural equipment (see Figure 1). This allows information to be shared among many vehicle systems and thus improves the operating efficiency of the entire vehicle. For example, by knowing the operating state of the engine, the transmission can optimize the gear ratio in a prime mover to minimize fuel consumption or maximize tractive effort depending on the operation.

Compliance issues

One of the main advantages of the ISOBUS network is also an area of prime concern for many professionals helping to develop the standard. ISOBUS is designed as an open network, which means that any type of compliant electronic device may be plugged into the implement side of the vehicle electronic system. Precautions must be taken to ensure that secondary devices are not able to inhibit normal vehicle operations. As shown in Figure 2, multiple networks are used. Critical vehicle information is allowed to pass along a secure network that is not open to other auxiliary products. This type of bus is defined as a closed network because unauthorized devices have limited access. On a typical agricultural tractor, the tractor bus, which contains engine, drive train, and other vehicle performance data, is normally a closed network. On the other hand, open networks exist that allow uninhibited data sharing between multiple points. These types of networks are termed implement buses on typical agricultural tractors and contain systems such as operation displays, field monitors, and precision agriculture sensors.

[FIGURE 2 OMITTED]

Several more sections of the ISO 11783 Standard are still under development and will dramatically improve agricultural equipment operations. The diagnostics section will enhance the operator's ability to troubleshoot problems when they occur and speed the vehicle's return to the field. Furthermore, a section that outlines file server handling will enable farmers to be in constant contact with previous field records and will incorporate new field operations directly into an ongoing database no matter what brand of equipment is being used.

Who is involved

Standardization of any type requires the dedicated efforts of many individuals and organizations. When standardization is applied to the agricultural equipment industry, though, the level of effort required is enhanced due to the complexity of the systems involved and the number of companies that compete within the industry. Currently, several committees and task forces are working together at multiple levels to refine the current standard, develop new standard sections, and promote standard implementation.

The actual process of standardization is via ISO, and ISO members are assisted by a technical advisor group (TAG). The TAG is comprised of numerous engineers working in industry with equipment manufacturers and others associated with various professional societies including ASAE and SAE. Other task forces or user groups exist to help define the needs of the standard and to promote standard implementation including the North American ISOBUS Implementation Task Force (NAIITF) and Implementation Group ISOBUS (IGI Europe). Each of these groups is open to new members and can be contacted directly for more information.

How to spot compatible vehicles

While most ISOBUS components are transparent to typical operators, there are a few features that users will come in contact with. One of these features is a terminator that is required for the CAN bus protocol to be implemented (Figure 3). It will be located at the beginning and end of each ISOBUS segment. ISO 11783 enhances the specifications of this terminator and requires that it be an active device. This is to increase reliability within the communication system. Another common device that operators will interact with is the electrical connector that links the prime mover and implements (Figure 4). This is much more sophisticated than the standard implement lighting plugs currently used on agricultural equipment. The connector is also an active device that senses when an implement is connected and will change operation depending on this state.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

What the future holds

Each year, more sections of the ISO 11783 standard are refined and progress through the approval process. Agricultural equipment products are already in production, with more being developed, that meet the criteria set forth in the ISO 11783 standard. These products are independently tested before an ISO Compliant registration is bestowed. As more products are certified, you will begin to see systems in production that are marketed based on an ISOBUS Compliant certification. This will be an enabling day for agriculturalists and will truly push agricultural equipment into the electronic age.

ASAE member Matthew J. Darr is a research associate II and instructor in the Food, Agricultural, and Biological Engineering Department at The Ohio State University, 212 Agricultural Engineering Building, 590 Woody Hayes Drive, Columbus, OH 43210 USA; 614-292-1406, fax: 614-292-9448, darr.27@osu.edu.

ASAE member Keith Hudson is a senior project engineer with Phoenix International, 2616 39th Ave. SW, Fargo, ND 58104 USA; 701-282-9364, khudson@phoeintl.com.