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Operator Access to Controls and Diagnostics Is a Matter of Skill

Jan. 5, 2010
Operator, Get Me Access Control: Systems Take on More Fault-Finding and Troubleshooting Duties

By Mike Bacidore, Managing Editor

As discrete manufacturing companies employ lesser-skilled machine operators, technology allows them to limit access to controls, minimize security breaches and automate an operator's interaction with the machine for fault diagnostics. But no standardized method exists for access control, and many systems are now doing more than just alerting and alarming.

Quite a few manufacturers use Windows security throughout their operations, explains Lorenzo Majewski, product manager at Rockwell Automation (www.rockwellautomation.com). "The same login used to access email is used to gain access to machinery or controls systems," he says. "However, when used on its own, Windows does not provide the granular security model that manufacturing requires. By using software tailored for use on the plant floor, in conjunction with Windows security or as a stand-alone option, manufacturers can define who has access to certain assets, who can view specific controllers and who can modify their programs. These software solutions also provide in-depth audit logs to track who made changes to the system, which can help identify the cause of problems when they arise." In addition, software from an automation vendor developed specifically for the plant floor is going to be deployable globally, which significantly reduces the amount of time manufacturers need to set up and manage their security systems, says Majewski.

HMI devices also integrate the same Windows login policies accepted plantwide to be applicable on manufacturing equipment, explains Alan Cone, HMI product marketing manager, Siemens Industry (www.usa.siemens.com/automation). As a result, supervisors can set up operator security profiles consistently on any computer in the facility. "Advanced HMI hardware and software products now include security features to the level of each individual graphic object, not just password protection at the screen level," he says. "Operators and supervisors can work from one screen, with different accessibility rights, and benefit from more consistent and fewer screens."

RFID systems often are used in machine access and maintenance tracking, says Tim Cicerchi, product manager, industrial bus & ID systems, Pepperl+Fuchs (www.pepperl-fuchs.com). "To access the machine, a person will take out a credit-card-style or key-fob RFID tag and swipe it over the reader," he explains. "If the person has authorization, that person will be granted access."

RFID can do more than just control access, says Cicerchi. "RFID systems can record the helpful data for future retrieval and reference, including the maintenance person's name, the time he or she accessed the machine and the amount of downtime," he says. "Many companies have key fobs with different colors, which can be a very helpful tool for visually inspecting a person's authorization level. Used as an access control system, RFID systems provide an automated trail of information that can help analyze and address situations in which a machine wasn't fixed properly or was down for too long."

Advanced audit-trail-security features provide configurable reporting for monitoring operator behavior, says Cone. "These features include time/date stamp on value changes, switch and button activity, along with reports on screen navigation sequences," he says. "Advanced audit features give supervisors and production people more tools to identify operational bottlenecks, solve repeating alarm tasks and determine procedure changes."

While some machines are simple and require no interaction, others might require displays where on-the-spot diagnostic information can be retrieved, explains Cicerchi. "If a machine fault happens, machine operators should be allowed to correct the problem," he says. "More difficult problems should only be taken care of by skilled operators."

The golden rule of troubleshooting a system is to know what changed, explains Majewski. "The ability to quickly determine who changed what on the system and when potentially can save thousands of dollars of downtime," he says. "Because software solutions provide audit logs, manufacturers can obtain detailed version control information. Coupled with the ability to limit who has access and the ability to make changes to specific assets, companies can prevent unauthorized changes that can create issues within the system. Moreover, if a problem does arise, they can see where changes that would cause the problem were made and more quickly and easily restore the system to a healthy state."

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