Setting Up WirelessHART
"The WirelessHART standard is built on proven industry standards," Executive Director Ron Helson says. "The radio uses the IEEE 802.15.4 standard and requires extremely low power, enabling the battery to last as long as 10 years in some applications. The radio operates in the same license-free 2.4 GHz band as Wi-Fi and many other wireless technologies. WirelessHART uses channel-hopping and channel black-listing to prevent interference and enable coexistence with other wireless networks, and a combination of star and mesh topology networking to ensure robustness in the presence of noise."
Helson continues, "WirelessHART uses the Electronic Device Description Language (EDDL) (IEC 61804-3) to simplify system integration as well as enabling setup, calibration and device diagnostics using graphical interface software applications."
WirelessHART was designed to operate reliably in a process plant environment that is full of structural steel, metal vessels and pipes using industry-accepted mesh topology. WirelessHART mesh networks are easily deployed without the need for installing a wireless infrastructure of backbone routers in many plant areas and providing power for them.
What you need to get started is a scale drawing or photo of your plant. Several companies make wireless sensor network management equipment that allows you to overlay the physical location of the sensors on the scale drawing, and tell you whether you need repeaters, more sensors or more gateways. For an example of this, see the Emerson AMS snap-in component in Figure 4 of "HART -- the Premier Tool for Asset Management."
Real World, Real Answers from WirelessHART
BASF had a real problem. Technicians needed to measure the temperature in a rotating vacuum dryer full of catalyst. Because the dryer rotated, wired temperature sensors had been eliminated. They were stuck with manual sampling and lab testing. They needed something better and faster.
"We went in search of alternatives so that we could dispense with the time-consuming sampling process and free up the operators," say Ramon Kranendonk and Perry Stofberg pf BASF in DeMeern, the Netherlands. "On the Endress+Hauser stand at a trade fair, we saw a demonstration of a wireless system for measuring temperature. The system used standard transmitters and a module with an antenna was used to transmit the data signal to a host by means of WirelessHART. For us, this was obviously an excellent solution."
Kranendonk noted that another criterion was the straightforward integration into the system. Control is via Siemens PLCs and PROFIBUS. Their asset management software is FieldCare. The Fieldgate gateway has 24 VDC power, and two outputs: one Ethernet, and one Modbus. The Modbus signal is converted to PROFIBUS DP and fed to the PLC. The Ethernet signal is sent to the FieldCare server.
"BASF has a number of good applications for wireless communication, and we are putting them to good use," Kranendonk says.
This application shows another unique feature of IEC62591-WirelessHART. A wireless adapter can be retrofitted to an existing HART wired transmitter to turn it into a fully functional wireless transmitter. Like the rest of the HART ecosystem WirelessHART adapters are being made by several vendors, including Endress+Hauser, Emerson (www.emersonprocess.com) and Pepperl+Fuchs (www.pepperl-fuchs.com). MACTek (www.mactekcorp.com ) produces a "Bullet" WirelessHART adapter that permits up to eight wired HART transmitters to operate wirelessly. Some of these wireless adapters provide their own power supply or can be used to power the transmitter, and some get their power from the current loop connected to the wired HART transmitter.
"WirelessHART easily scales to support large applications with separate networks for each plant area aligning with DCS structures and division-of-work responsibilities that make it easy to manage and more secure," Helson says.
Northstar Bluescope Steel had a real problem. The steel mill has water-cooled electric arc furnaces, with water-cooled burners and cooling panels that keep the furnace walls from melting and deforming—and blowing out the panels. If that happens, the furnace is seriously damaged, and just one blown-out panel costs upwards of $20,000 to repair. Then there is the lost production cost due to the unexpected downtime. That can be as much as an additional $200,000 per day or more.
"Between nine and 12 measurements per week would fail due to high temperatures or physical damage to sensors, cable or conduit," says Rob Kearney, maintenance supervisor of Northstar's mini-mill in Delta, Ohio. "And when a measurement point fails, the furnace must be shut down. The new wireless solution eliminated almost 100% of the cable and conduit—which reduced maintenance costs by $200,000 annually."
The self-organizing WirelessHART network collects the data used to control temperature on the furnaces. Emerson provided 32 Rosemount WirelessHART temperature transmitters, 28 for control and four for monitoring. The transmitters send their data to aWirelessHART gateway which interfaces with the mill's transformer-regulation and burner-control system.
"Safety has also been improved," Kearney says. "The furnace's cooling panels are operating consistently at a safe temperature, and there is less maintenance required around the hot furnace shell, where ambient temperatures can be +140 ºF."
Is HART Future-Proof?
The process industries, in fact, all manufacturing, are very conservative. Refineries and chemical process plants especially don't like trying new things, because a failure generally makes something go boom. Pharma and biopharma plants and other validated industries are similar in conservative application of new technologies.
But HART and its wireless capability, WirelessHART, aren't new. They are both based on the proven technology that has made HART the standard for process fieldbus. And going forward, you don't have to fear that suddenly the devices will become obsolete. Endress+Hauser is one of the world's two largest field instrument manufacturers. Here's what Jason Knuteson, E+H wireless product manager, has to say, "The long-term investment and commitment into the WirelessHART and other wireless communication is 100% from E+H. This is a decision made at the top levels within our organization! We are committed to the needs of our customers."
David Skelton, Phoenix Contact's (www.phoenixcontact.com) vice president Americas sums it up well. "Process engineers around the world are using WirelessHART as a way to easily obtain data from their existing HART or newWirelessHART instruments. With this gateway, Phoenix Contact has combined our competencies in wireless, networking and process technologies to develop a product that makes WirelessHART networks even more cost-effective and flexible."