This article was printed in CONTROL's August 2009 edition.
By Dan Hebert, Senior Technical Editor
Many suppliers offer integrated systems capable of controlling and monitoring all process plant regulatory control, advanced process control, safety and security functions. That leaves just one separate island in process plant control and communications system—telecommunications. Process plant telecommunication systems encompass PA and paging systems, various handheld personal digital assistant devices, video camera systems, and wired and wireless phone systems. Tight integration of telecom with plant control systems provides a number of benefits.
"The control room console can have a uniform layout of all systems on the operator's screen, allowing for better operator ergonomics," explains John Oyen, manager of business development at ABB. "Giving the operator a uniform user interface for all networks, and limiting his or her view of the networks to task-dependent information simplifies the work processes. System security is available, so access to all systems can be made task- and user-dependent. Event logging, messaging and automated actions are standardized and configurable to alert the right person to take the correct action. Bringing telecom network equipment into the asset management realm yields uniform presentation of equipment status and streamlines maintenance."
Telecom systems can be integrated into the rest of the plant's control and communications system in three basic ways. First, one can buy components and systems from various suppliers and then integrate same into the plant's control and communications system.
The second method is a variation of the first. A wireless network can be installed to interface with all telecom components and systems, and this wireless network can then be tied back to the plant's control and communications system. Third, one can work with a single supplier for control, security and telecom.
The first option allows a plant to purchase and install the best-of-breed in each category, minimizing initial purchase costs and maximizing performance specs. It also gives plants freedom to change parts of their overall control and telecom systems without starting anew.
The disadvantage the first option is the integration. Although each separate system may work just fine on a standalone basis, problems often arise when systems are linked together, and it can be very difficult to pinpoint their exact nature and affix responsibility to the offending vendor.
One way to reduce integration issues is to use a single vendor's wireless backbone network throughout the plant to communicate with all telecom components and systems. This wireless backbone network is then tied back to the plant's main control and communication system, and the wireless vendor assumes integration responsibilities.
"We provide secure and scalable enterprise-wide wireless solutions that can be integrated with telecom end-devices for flexible communications," says Hesh Kagan, managing consultant of enterprise architecture and integration for Invensys Process Systems. "Our wireless, plant-wide infrastructure supports devices like Motorola's MC75 family of handheld devices that provide VoIP, cellular and data communications. Many of these devices can support scanning functionality for bar code and RFID, so by using one handheld device the operator is now fully mobile and capable."
The third solution is to use one vendor. This approach is the best solution to the integration issue, but it tends to lock the plant into that vendor's entire suite of products.
ABB is one of the few vendors with the capability to provide and integrate telecom and control. Oyen explains the benefits of the arrangment. "Using one vendor to integrate and take responsibility for telecom, automation and electrical systems minimizes project risk, defuses commissioning problems and increases operational efficiency," he says.