By Dan Hebert, PE, Senior Technical Editor
AS Your customers use handheld wireless human-machine interface (HMI) units more frequently, it's important that you understand how best to make your machines fit their overall wireless infrastructures. Increasingly, compatibility with existing and planned wireless machine monitoring systems will be a required feature.
For example, Mohawk Fine Papers (www.mohawkpaper.com) in Cohoes, N.Y., uses Transpara's Visual KPI to monitor and control its paper machinery and other plant components.
Key performance indicators (KPIs) are delivered to handheld HMIs, in this case Blackberry devices. Data isn't accessed directly from machines, but instead primarily through OSIsoft's PI data historian. Other data are delivered to the Blackberry devices through Microsoft SQL Server for data extraction, transformation and loading, and through Microsoft Sharepoint as an information portal.
Everyone in the plant has access to the data via their Blackberry devices including technicians, managers, supervisors, engineers and even the chief operating officer. Handheld HMIs played an important role in Mohawk's overall 2009 improvement in machine output, customer satisfaction and energy consumption.
"Supervisors and senior managers now have real-time access to machine, production and order status," explains Ben Whitaker, manager of enterprise process reengineering at Mohawk. "This allows more responsiveness to customer requirements and manufacturing issues. In the maintenance area, supervisors and senior engineers have access to energy consumption for better response to machine performance issues."
Machine OEMs supplying Mohawk and companies using similar systems need to make their machine control system accessible to the data repositories accessed by handheld HMIs. This means that links must be provided to software such as data historians and often to various Microsoft products as well.
These links are most commonly Ethernet-based, meaning that your machine should have an Ethernet port at either the controller or the HMI level. This takes care of the hardware connection, but doesn't address the software protocol issue. Most manufacturers use one or more Ethernet protocols in their plants, and it's incumbent on the machine builder to ascertain which type of protocol is needed and to provide the machine with same.
Although many companies use handheld HMIs for machine monitoring, few are using them to replace the primary machine-mounted HMI. The handheld HMIs are instead used to extend reach, usually via one-way communication of machine status. Any problems requiring adjustments to the machine control system typically still will be made at the machine.
Future implementations might feature high-speed two-way access. This would allow your customers not only to monitor their machines remotely, but also to change control parameters to adjust machine operation. These types of adjustments probably will be made by operators in close proximity to the machine, paving the way to systems that completely eliminate on-machine HMIs.
In these types of systems, your machine would be provided with no local HMI. Instead, a handheld wireless HMI would be used to provide full monitoring of your machine along with adjustment of machine operating parameters. The advantages of such a system to manufacturers are numerous.
First, one handheld HMI could be used to monitor and adjust many different machines. In typical plant operations, an operator goes from one machine to the next to observe operating conditions and make adjustments.
Second, an operator could access a machine from a safe distance, often outside a hazardous area. This not only could improve safety, but also save time as personal entrance into a hazardous area is often a time-consuming task requiring special protective personnel equipment (PPE) and lots of paperwork.
Third, linking the handheld HMI to the machine and to the central control room could allow an operator to make machine adjustments with the entire process in mind.
