with many advances in automation, the enabling technology underlying remote diagnostics and maintenance has been the continual increases in processing speed and memory of the controllers. “This allows for the embedding of functionality that was not possible before,” explains Ted Thayer, automation systems product manager at vendor Bosch Rexroth Corp., in Hoffman Estates, Ill.

“For example, a programmable logic controller (PLC) that I used back in 2002 had a processor that ran at 20 megahertz (MHz) and had about 128 KB (kilobytes) of total memory,” he offers. “The lowest-end PLC that we sell now has a processor that clips along at 166 MHz with 32 MB (megabytes) of memory, which allows for using software tools such as a Web server and provides for extensive Ethernet functionality.”

Protocol for pulses

As crucial as Ethernet and other communications technologies are, they are not the only ones that make remote diagnostic and maintenance services possible. Standards also have been playing an important supporting role. Perhaps the most prevalent one is the simple network-manager protocol (SNMP) promulgated by the Internet Engineering Task Force (IETF), an open standards organization that is part of the Internet Society, in Reston, Va.

The protocol allows management systems to monitor networked devices for problems by presenting management data, such as diagnostics information, as variables that application software can query. “It allows diagnostics information to be more transportable over existing infrastructures, both intra-networks and inter-networks,” notes Jansons at Siemens. “Most devices, including a lot of PLCs, support it now. So, not only can they use diagnostics in their native control languages, but they also can leverage this information by sending it via Ethernet.”

This capability has great potential for the support services that machine builders and automation vendors are offering users of their equipment. “More than 80 percent of machine faults can be effectively diagnosed remotely,” estimates Kerry Sparks, senior field marketing specialist at Cleveland-based Eaton Corp. A technician at a remote location can either correct the problem by modifying the software on the PLC or human-machine interface (HMI), or alert local technicians to take the necessary corrective action.

“With good predictive modeling, estimates are that 30 percent to 50 percent of machine downtime can be prevented when the right people are notified of impending problems in a timely fashion through paging, e-mail or text messaging,” concludes Sparks. In these ways, checking a machine’s pulse from afar permits an early diagnosis that can cure problems before they have a chance to hamper a machine’s productivity and cause unscheduled downtime.

Subscribe to Automation World's RSS Feeds for Feature Articles