Showing posts with label HART. Show all posts
Showing posts with label HART. Show all posts

Tuesday, October 31, 2017

Understanding HART Protocol

A current loop using sensing and
control transmission with HART protocol
overlaid on the 4–20 mA loop.
The Highway Addressable Remote Transducer Protocol, also known as HART, is a communications protocol which ranks high in popularity among industry standards for process measurement and control connectivity. HART combines analog and digital technology to function as an automation protocol.

A primary reason for the primacy of HART in the process control industry is the fact that it functions in tandem with the long standing and ubiquitous process industry standard 4-20 mA current loops.

The 4-20 mA loops are simple in both construction and functionality, and the HART protocol couples with their technology to maintain communication between controllers and industry devices. PID controllers, SCADA systems, and programmable logic controllers all utilize HART in conjunction with 4-20 mA loops.

HART instruments have the capacity to perform in two main modes of operation: point to point, also known as analog/digital mode, and multi-drop mode. The point to point mode joins digital signals with the aforementioned 4-20 mA current loop in order to serve as signal protocols between the controller and a specific measuring instrument. The polling address of the instrument in question is designated with the number ì0î. A signal specified by the user is designated as the 4-20 mA signal, and then other signals are overlaid on the 4-20 mA signal. A common example is an indication of pressure being sent as a 4-20 mA signal to represent a range of pressures; temperature, another common process control variable, can also be sent digitally using the same wires. In point to point, HART’s digital instrumentation functions as a sort of digital current loop interface, allowing for use over moderate distances.

HART in multi-drop mode differs from point to point. In multi-drop mode, the analog loop current is given a fixed designation of 4 mA and multiple instruments can participate in a single signal loop. Each one of the instruments participating in the signal loop need to have their own unique address.

Image courtesy of  Dougsim (Own work) [CC BY-SA 4.0], via Wikimedia Commons

Monday, April 17, 2017

The Meriam MFC5150x Intrinsically Safe HART® Communicator

MFC5150
Meriam MFC5150
Available in ATEX (intrinsically safe) and Non-ATEX models, the Meriam MFC5150 directly reads Device Descriptions without any translations or subscriptions, enabling communication to take place with any registered or unregistered HART® device. This ensures your HART® transmitter will connect, regardless of brand or model.

The MFC5150 is built on the SDC-625 infrastructure and runs Windows CE. With a 1GHz processor and an 4GBMicro SD card, this HART® communicator is ideal for all of your data storage needs.

The 4.3 inch touchscreen provides excellent anti-glare viewing, allowing for comfortable mobile use in darkness or in bright sunlight. All functions are easily navigated via the full QWERTY keyboard and intuitive icons similar to that of a smart phone.

The handheld HART device also features hyperlink menu paths, teachable device specific shortcuts, instant on, multiple languages, help context, video’s and TAB access to panes just like on a computer.



For more information visit Flow-Tech here, or call 410-666-3200 in Maryland or 804-752-3450 in Virginia.