Purvis Industries in Dallas is a manufacturer of material handling and mechanical systems, such as conveyors, motors, drives and fluid power systems. So, not only do they have to use device networks to control their systems, they have to be concerned about supporting the network in the field.
Support of their products depends on both the customer and the system integrator that installs the equipment. "One of the major determining factors for recommending and implementing a control network is the talent level that the end user has on site and their ability to support the control system," says Brian Radichel, business development manager at Triad Industrial Automation, the technical arm of Purvis Industries.
"It does an integrator no good to implement a solution that might be successful but requires many trips back or multiple phone calls to support the customer. First-line support, when provided by the customers themselves, enhances the integrator’s offering by giving the customer a sense of ownership and competence to handle their own issues."
Support also depends on tools available for monitoring and diagnosing network problems. "Ethernet has the advantage of a common connection type (RJ45) and the ability to use shareware packet sniffers such as Wireshark to monitor the network," Radichel notes. "Profibus is very difficult to monitor without expensive monitoring tools and software. Ethernet is also generally scalable to a machine level or process level within the 100 m copper distance range. Auto-negotiating switches and the flexibility of managed switches give the integrator a lot of control over the network’s performance."
Installation and setup vary among the networks. "Modbus TCP and EtherNet/IP have a wide installed base and are reasonably simple to set up, using now familiar IP addressing," he says. "EtherCAT has introduced determinism and an even faster switchless topology while maintaining familiar media. Profinet is extremely fast, reliable, and features a one-point setup tool that allows easy commissioning of the network at one sitting."
All networks have their particular advantages. "Ethernet-based communications have an advantage in simplicity for small-to-medium, rapid installations, and ease of use in troubleshooting. EtherCAT and Profinet get high marks for speed and ease of use. Serial fieldbus still has its place for distance, speed, and device count. Profibus remains available for instrumentation and other devices, and doesn’t seem to be threatened by other fieldbuses at this time."