Have you ever heard about the bi-directional HART communication protocol? I haven’t, but I should probably have as there’s an installed base of over 40million HART-enabled instruments according to FieldComm Group who owns the protocol and the organization is comprised of 375 corporate members working on process automation instrumentation, systems, and services. HART stands for Highway Addressable Remote Transducer.
The organization is also maintaining the more recent (2009) HART-IP IP-enabled version of the HART field communication protocol and just launched HART-IP Developer Kit whose hardware is comprised of a Raspberry Pi 3B+ SBC and off-the-shelf add-on boards mounted on a DIN Rail mount.
List of all hardware components:
- Raspberry Pi 3B+ SBC
- DSLRKIT Power Over Ethernet PoE HAT (around $20 on Aliexpress)
- Waveshare Raspberry Pi High-Precision AD/DA (about $30)
- DINrPlate DIN Rail Mount.
- MicroSD card
On the software side, the system runs Ubuntu MATE 18.04 64-bit preloaded on the MicroSD card with two software module:
- The HART-IP Server (hipserver) takes care of all HART-IP specific functions plus manages client subscriptions. The client subscriptions allow the hipserver to push the process and status data to client applications.
- The Flow Device Application (hipflowapp) implements a complete flowmeter with data going through the AD/DA board, and provides an example of a complete HART-enabled field device.
Both software components can be found on Github, and documentation on the company’s support website.
Based on the diagram above, I then understand a HART-IP client on another Ethernet-connected computer can then retried the data over HART-IP communication protocol.
The actual network topology in the field is a bit more complicated with gateways, multiple field devices, a firewall, a “historian systems”, and a management computer.
The company also explains the advantage of HART-IP over competing protocols such as MODBUS RTU:
Since the application layer is the same for HART field devices as HART-IP, time-consuming and error-prone data mapping required by MODBUS RTU is eliminated.
The HART-IP developer kit may eventually be updated by replacing the PoE module by a 2-wire Ethernet-APLif such component becomes available. There will also be updates with FieldCommGroup’s OPC UA-centric Process Automation Device Information Model (PA-DIM) for interoperability with OPC UA based enterprise applications, and support for JSON and XML basedDeviceInfofiles for use with IIoTedge gateway solutions.
The hardware used for the kit costs around $100, so you’d be mostly paying for the software and the 4 hours of included technical support, as the HART-IP developer kit goes for $995 for members of FieldComm Group, and $1,495 for non-members.
Via LinuxGizmos and EENews
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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Hart is usually used in process automation and mostly in a price range far above the hobbyist’s capabilities.
I worked around the millennium for endress + hauser you could buy one or two compact cars for the price of a flow meter pre sales organisation mark up…
Definitely quality products developed by proud engineers and manufactured in house. That was a good time.