The ARC Insight “HART-IP Brings HART into the Internet Age” notes that “The 25-year old HART protocol still provides the digital communication interface for the vast majority of process field devices in today's market”:
http://www.arcweb.com/strategy-reports/2014-09-19/hart-ip-brings-hart-into-the-internet-age.aspx
Problem is though, that 4-20 mA/HART is predominantly used only with a handheld field communicator or laptop with interface and software. Permanent ‘always-on’ integration of 4-20 mA/HART communication is still very rare for various reasons.
ARC points out that WirelessHART is the most notable addition to the HART protocol. Since that time HART-IP has also been added as a third protocol. HART-IP, as the name suggests, is the HART protocol over IP network such as Ethernet, Wi-Fi, or 3G etc. ARC notes that “At present only a dozen or so HART products use HART-IP, mainly to provide a simple means to backhaul data from HART multiplexers and gateways in remote locations”. That is, HART-IP is predominantly used in WirelessHART gateways as a backhaul network to get the data from the wireless sensors to steam trap monitoring software, to asset monitoring software, and spectrum/waveform to machinery health management software, as well as device data to Intelligent Device Management (IDM) software from various manufacturers. That is, thanks to HART-IP, WirelessHART can be integrated into the IDM software associated with the control system from many manufacturers, not just Emerson. Learn more about HART-IP from these articles;
Hart-IP: Large Scale System Integration
http://www.ceasiamag.com/article/hart-ip-large-scale-system-integration/9526
Smart Sensing: Situational Awareness
http://www.iaasiaonline.com/more.php?id=2222&cat=im
Power of Two - New Wireless Solutions for Plant Operations
http://www.ceasiamag.com/article/the-power-of-two/9121