PDA's in the Field

Affordable technology leads to diagnostic tool for mobile applications.

Kar-Tech Inc., Delafield, WI, manufactures microprocessor control systems for a wide variety of mobile machinery and heavy-duty applications. The company designs and manufactures everything from steering controls on asphalt pavers to closed-loop controls on salt and sand trucks to radio remotes for concrete pumpers at its on-site manufacturing facility.

One unique aspect to the design of all the company's control systems — from simple to sophisticated — is an eye toward diagnostics. Kar-Tech's president, Hassan Karbassi, believes that one of the biggest barriers to the full-scale adoption of electronic control systems is the inherent fear of not being able to easily see what the problem is if a machine or system fails.

Kar-Tech has come up with a unique, effective and relatively low-cost method to overcome this challenge — a patented PDA-based diagnostic tool.

"Engine ECUs are commonplace today," says Karbassi. "So dealerships and fleet owners can often justify the investment of an engine service tool. But with other electronic systems, such as controls on relatively low volume equipment like digger derricks and fire and rescue equipment, the investment in a service tool cannot be as easily justified."

In the late 1990's, Kar-Tech engineers were trying to solve this problem of making the electronic systems more "visible" from a diagnostic standpoint to both the OEM customer and the end-user while also keeping the solution affordable.

It was also at this time that Palm Pilots and other personal digital assistants (PDAs) started becoming popular.

The relatively inexpensive PDAs provided an ideal solution to the diagnostic problem and Kar-Tech underwent extensive software development to patent and provide an effective PDA-based diagnostic tool for industrial control and monitoring.

The PDA solution allows the end-user to complete a number of different functions in the field without the expense of a laptop service tool:

Diagnostics. Technicians can use the tool to easily troubleshoot problems with the control systems.

"For example," says Karbassi, "take an application in which the crane was not operating properly. We discovered the problem when we hooked up the PDA to the truck and saw that it was reading only 10.9 volts for the truck battery voltage and we had a pressure transducer error in the histogram." From the readout on the PDA, they discovered that the alternator was not hooked up properly and a wrong pressure sensor was installed.

"Most people aren't familiar or comfortable with electronics or using a volt meter and breaking into wires to attempt to find the problem. But it's very easy to hook up a PDA and read the error codes to see what the problem is," says Karbassi.

Histogram. Not only can the PDA be used for real-time troubleshooting, it can also be used to look back at the performance of the machine to help with intermittent problems.

Let's say you've got an operator that says, "Every time I move the joystick, the controls cut out." With this PDA-based tool, the mechanic can go out to the unit and a pull a historical reading of the machine operations. From the histogram, the mechanic can tell that the wire from the joystick broke five times and show the dates and times that it was broken. "If you don't have this ability to go back and look at what went wrong in the field, when the operator tells you something is wrong and the machine is behaving in a certain way, you can start repairing something unrelated to the real problem due to the way the machine is acting," says Karbassi.

Calibration. The tool can also be used to calibrate proportional valves, sensors, logic parameters, or a number of other settings.
Kar-Tech offers a number of different interfaces for the PDA tool to hook up to the machine including the standard PDA cable interface, radio frequency interface, and an infrared interface.