By Dan Hebert, PE, Senior Technical Editor
If you're a machine builder or a system integrator, no one has to sell you on the benefits of remote diagnostics. What used to be a value-added feature is becoming a requirement from your customers and a competitive necessity for your company.
There are three main ways to perform remote diagnostics. The first is with a PC-based control system, the second is with a PLC-based control system, and the third is with an interface component such as an embedded computer.
No matter the approach, the benefits to the machine OEM include reduction in travel, faster response to problems and more-efficient use of technical personnel. OEM customers will see reduced downtime, reduced requirements for internal technical personnel and more efficient machine and robot operation.
The PC-based approach was implemented by Control Logic, a Hickory, North Carolina, machine builder. Control Logic made systems for lumber ripping, grading and tracking—and has been succeeded by Aiken Development, also in Hickory.
Control Logic upgraded its controls from a PC-based operator interface and a PLC controller to a PC-based system from Beckhoff Automation. The new system provides all required functionality including control, operator interface and diagnostics.
"Using a single PC platform allowed us to remove extraneous interface layers used in the previous system design and also reduced costs and space requirements," says former Control Logic President Chris Aiken.
The main drawback of this approach to remote diagnostics is that it means replacing the entire existing automation system with a PC-based solution.
For industrial OEMs that want to stick with a PLC, an alternative is to couple a low-cost PLC with an inexpensive operator interface terminal. This was the approach taken by Pratt Industries, a manufacturer of paper and corrugated products.
Pratt needed a control and data-collection system for its material recovery recycling plant in Shreveport, Louisiana. Pratt selected an AutomationDirect PLC communicating via Ethernet with touchscreen display panels in the pre-sort, post-sort, baler and main operator console areas.
"The FTP transfer function from the HMI provides the ability to continually monitor production data, plant statistics and equipment fault conditions over the Web," explains Greg Philbrook, HMI/communications product manager at AutomationDirect (www.automationdirect.com). "Fault screens monitor the status, and management can view them securely over the Web on a 24/7 basis."
The main advantage of this approach is that PLC technology familiar to many builders and integrators can be combined with a low-cost operator terminal. Because this operator interface is a Web server, it can be accessed by any browser.
The main disadvantage to this approach is that it can force the machine builder to change its controller, its operator interface or both.
The third approach lets machine builders keep their existing control systems. A low-cost embedded computer is added that connects to the existing control system, providing a wide range of remote connection options.
This approach was selected by ABB Remote Monitoring for its robotics division. ABB uses an Advantech embedded automation computer to monitor diagnostic information from the robot controller.
"If there's a robot failure, the diagnostic data is uploaded through the embedded computer and sent to ABB wirelessly via a cellular modem or the Internet," relates John Wilhite, embedded automation computers product manager at Advantech (www.advantech.com).
During a robot alarm or error event, a complete backup of the robot programs and diagnostic logs are posted to the password-protected ABB website. A series of alerts are sent to ABB technical support specialists.
By examining the fault logs, ABB can establish the root cause, recommend proper corrective actions and provide technical assistance until the problem is fixed. The customer receives a root cause analysis so that corrective and preventive actions can be implemented.
The advantage to this approach is the existing control system can be used. The disadvantage is a second hardware component must be purchased, programmed and installed.
