In addition, Tennant is using software from Persystent Technology Corp. in Tampa, Fla., to ensure that the data on a tablet PC is not altered by the user or through an attack or errant software update, Hayes said. Persystent works by storing a copy of the basic operating system in a hidden partition on the tablet PC, and making a quick comparison during the boot up process. Any inconsistencies are cleaned up, and the process doesn't slow the reboot process noticeably, he said.

In addition, Afaria software, made by Sybase Inc.'s iAnywhere business unit, provides management for the mobile devices and can deploy software and patches as well as the complex documentation for technical manuals needed to make repairs, Hayes said. Updates of the manuals reach the technicians within a day of publication, compared to months needed under the old paper-based system.

The system followed careful scrutiny of about two dozen vendors in the field, Hayes said. Before picking Dexterra, Tennant had tried to deploy a home-grown field service application, but had to abandon it in 2003, Hayes said. "We had to stop and start over...," he said. "We refocused our energies and learned to get 80 percent of the technology issues right and to focus on what's most important. We learned to get the project out and let it evolve."

The payback is coming partly from exceeding goals on automation of parts order processing and from billing, which used to take 10 to 12 days. It now takes just a day or two, he said.

Tennant's help desk has reported that service reps are "enthralled" with the application and won't give it up.