At least seven and perhaps up to as many as eleven more companies expect to have WirelessHART products on the market by summer. You'll find out who all of them are as they give me permission to announce their products.
These companies include field device manufacturers, but there is a healthy leven of companies that see an opportunity to provide WirelessHART adaptors for the enormous existing installed base of HART transmitters. At least three companies like that are in the final stages of preparing a WirelessHART offering that includes an adaptor and a WirelessHART gateway.
These companies are taking advantage of the fact that, unlike any other wireless protocol, a WirelessHART adaptor does not need to be located close to the transmitter or other field device. Existing HART transmitters are connected to the control system by a 4-20 mADC umbilical, and the WirelessHART adaptor can be located anywhere along the 4-20 loop that it is practical to put it.
This is a very good thing in those "caverns of steel" that are refineries, chemical plants, and biopharma plants. I just have a real hard time imagining getting a decent radio signal from a pressure transmitter mounted at the outlet of a 20 foot diameter evaporator, or some really large vessel on very stubby legs...just enough room for a control valve and a transmitter under there. The fact that a WirelessHART adaptor can be located many feet away, where there's a decent spot for reception of radio signals is a huge advantage, even going forward.
I do not believe that most WirelessHART implementations will be battery-driven and completely wireless. I think most will use the 4-20 for signal and power, and provide WirelessHART for digital data transmission.
This is going to be an interesting year.