Emerson Exchange 365
Search
Sign-In / Register
Site
Search
Sign-In/Register
Services
Products
Control & Safety Systems
Asset Management
Measurement Instrumentation
Valves, Actuators & Regulators
Fluid Control & Pneumatics
Electrical Components & Lighting
Welding, Assembly & Cleaning
IIoT & Digital Transformation
Industries
Chemical
Food and Beverage
Industrial Energy
Life Sciences
Oil & Gas
Power
Refining
Other Industries
Women in STEM
Events
Düsseldorf 2024
Immerse - Anaheim 2023
Grapevine 2022
Nashville 2019
San Antonio 2018
The Hague 2018
World
China
South Korea
Russia
More
Cancel
Products
More
Valves, Actuators & Regulators
Valves Forum
Use of 250ohm resistance in HART Communication?
Forums
Blogs
Library/Resources
Members
Tags
More
Cancel
Create New Post
Comment or Question? Become a member of this Emerson Exchange 365 group. Click here to join.
Recent Valves, Actuators & Regulators Discussions
mark.nymeyer
31 May 2022 12:44 PM
Article: Proper Valve Stem Sealing Best Practices
0 Replies
mark.nymeyer
16 May 2022 12:37 PM
Article: Alternative control valve repair solution yields savings
0 Replies
mark.nymeyer
9 May 2022 8:49 PM
Article: Staying Ahead of Environmental, Social, and Governance Goals
0 Replies
mark.nymeyer
5 Jan 2022 8:29 PM
Article: Simplifying control valve packing selection
0 Replies
mark.nymeyer
23 Dec 2021 5:29 PM
Article: Select the Right Control Valve Materials
0 Replies
<
>
Similar Posts
Corrosion-Resistant Materials in Chemically-Hostile Valve Applications
Corrosion-Resistant Materials in Chemically-Hostile Valve Applications
new DVC not communicating with HART communicator
Interrogating a DVC type HC positioner with a HART 475 communicator
DVC6030 - HART Not Communicating at 20mA with SLS Two-state output channel?
Share
Answered
Use of 250ohm resistance in HART Communication?
Why is it necessary to use a 250ohm resistance in HART communication?
All Responses
Answers Only
Jonas Berge
16 Dec 2014 11:50 AM
It doesn't have to be exactly 250 ohm. Anything from 230 - 1100 ohm will do
The reason it is required is that the HART signal is transmitted as a current and received as a voltage. The resistor works as a shunt that converts the transmitted current to a voltage the other device receives. The second reason it is required is because a DC power supply will short circuit the AC HART signal. The resistor prevents this from happening.
Note that this resistor is only required for transmitters. It is not required for positioners.