The HART Ecosystem - Wired and Wireless

Interoperability Breeds Competition - And That's Good for End Users!

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WirelessHART is giving companies that aren't known as field device manufacturers the ability to provide key building blocks of the WirelessHART ecosystem. For example, Pepperl+Fuchs—long known as a networking company, but not as a process transmitter supplier—is supplying gateways both under its own brand and as a private label to other suppliers, as well as a WirelessHART adapter and a temperature converter that converts two temperature sensor values to WirelessHART.

Phoenix Contact (PC) is also producing a WirelessHART gateway. Ira Sharp, product marketing lead for wireless for Phoenix Contact, has some thoughts on the security of the WirelessHART network that is connected to his gateway. "WirelessHART uses 128-bit AES encryption for over-the-air communications. This is the same encryption that is used in WPA2, which is the de facto standard for Wi-Fi communications and is accepted by IT professionals around the world," Sharp notes.

"Couple that with a hardened join process for WirelessHART devices requiring every device to have a join key and the ability to change the active advertising features in gateways, and you can limit the accessibility of the network," he points out. "As with any network," he continues, "when looking at network security, there are two things that must be considered. Is the data protected as it flows over the medium (like wireless), and are the devices that are on the network suppose to be there? This relates to encryption and authentication, and WirelessHART covers both of these aspects."

NIVIS is also providing a gateway product, as well as becoming one of the four firmware stack suppliers for WirelessHART. The firmware stack is a chip and code set that takes a standard IEEE 802.15.4 radio and makes it WirelessHART. The fact that there are now four different vendors for the stack indicates how robust the standard is and how interoperability is built into the system from the firmware layer out. NIVIS provides a complete WirelessHART development kit for companies who wish to use its firmware stack.

Siemens, too, has jumped on the HART 7 and WirelessHART bandwagon, with a preliminary offering of pressure and temperature transmitters, a WirelessHART adapter and a WirelessHART gateway. Siemens is also producing a maintenance and diagnostic station to extract and manage maintenance information from wired and WirelessHART field devices.

Endress+Hauser, the world's largest supplier of field transmitters, has produced a WirelessHART adapter and a new version of its Fieldgate protocol gateway to work with WirelessHART. This way, any existing E+H field transmitter can be quickly and easily retrofitted with WirelessHART, and, through the Fieldgate and OPC, communicate with a control system. According to Victor Wolowec, E+H vice president of solutions, "Adding adapters immediately allows any HART 5 device to enter a WirelessHART network and transmit its information to the gateway. This might be process values for monitoring applications or health data which is not normally available over a 4 - 20 mA connection."

But it isn't just large companies like Emerson, Siemens, Endress+Hauser, Pepperl+Fuchs and ABB who're bringing out innovative WirelessHART products.

MACTek's Thomas Holmes talks about the MACTek "Bullet," a most interesting implementation of the specification for WirelessHART adapters. "The Bullet WirelessHART adapter is an intelligent communication device that provides cost-effective wireless connectivity to both existing and new control and monitoring applications," he says. "This device is much more than a simple router or converter and should be considered as being more like field-hardened intelligent I/O."

MACTek's product is an example of the diversity of the HART Communication vendor community.

While there are other WirelessHART adapters, MACTek has taken the adapter concept considerably further than most—and it continues to be entirely interoperable with other devices. Holmes describes the product. "MACTek will offer eight Bullet models differentiated by hazardous-area certification (GP, IS, XP and XP-IS) and by the number of HART field devices supported in HART multidrop mode (two and eight supported devices)," he says. "Every Bullet model supports one device in standard (non-multidrop) HART communication mode or will transmit the measurement PV from a non-HART analog device."

ProComSol does HART 7. Its HART modems and PC-based software work fine with HART 7, because it is backward-compatible with all the HART versions before it. "One of the most important new capabilities of HART 7," says Mike Fersky, marketing manager of ProComSol Ltd., "is exception reporting." In exception reporting, the device only reports data if it is significantly different from what went before.

From the largest automation companies to some of the smallest, the depth and breadth of the HART technology ecosystem, wired and wireless, and the HART standards-based solution make the choice of HART communication for any plant an easy one.

Registering a HART device

In 2009, the HART Communication Foundation board of directors voted to require independent testing in order to register a HART device, wired or wireless. This testing is an addition to the testing required of the manufacturer prior to registration testing.

"To verify compliance with the HART Protocol Specification, wired and wireless devices that claim to be "HART Registered" must pass the HART Device Registration Program conducted by the Foundation," says Foundation executive director Ron Helson. "HART registration is available for all process measurement devices, interfaces such as modems, multiplexers and I/O systems, HART masters including systems and handhelds and Device Description (EDD)-enabled host applications."

"100 percent verification tests are conducted to confirm compliance to the HART Protocol standard," says Ed Ladd, HART Communication Foundation director of technology programs. "Running the tests ourselves and independently verifying that submitted devices meet the intent of the standard ensures interoperability—reducing the risk of problems in the field."

But before the Foundation gets the device to test, the manufacturer must do the testing itself—and provide the data to the Foundation, as well as a device for testing. The list of requirements is long, and the procedure is rigorous. "Both good and bad data are sent to see that the device responds appropriately," Ladd says. "For example, test DLL 039 stress test involves two million messages. Devices have to interoperate and be robust on the network," Ladd continues. "To be ‘registered,' a device can miss no more than 20 messages."

Why the detail and rigor? "If you're replacing a device at 2:00 a.m.," Ladd says, "you need to know it's going to communicate—no matter who manufactured it. That's what the registration process is all about."

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