Handheld and HART
Should I always have a 250-ohm resistor to use the handheld communicator with a HART device?.
Expert’s answer: How to use a handheld and HART together
OK, using a handheld and HART together… As you know, HART communication sends digital data on an analog signal. To do that, the HART reads the frequency of 1200 hertz as “1” and 2200 as “0.”
For the handheld to read the HART signal on the loop, you need to have a minimum impedance. Most of the time, the control system has an internal 250-ohm resistor in each channel, but not always.
The HART Foundation suggests a minimum loop resistance of 230 ohms. However, the 250 is standard, so you can easily find such devices on the market.
If you try to communicate with a handheld and it fails, then you may need to insert the handheld in series with the loop.
These companies provide HART networks:
Handhelds available on the market:
Other resources that might interest you
HART communication and Viator Bluetooth interface
Can I use a Viator Bluetooth with my software? I have an AMS suite device manager.
HART communication and Industrial IoT system
Can you use an IIOT platform with a HART field device?
HART – The best PAM application
We only get the analog signal to our HART field devices! How can we upgrade the system to read the diagnostics?
Multifunctional switch panel process measuring device for monitoring and displaying analog measured values
Multifunctional field indicator for monitoring and displaying analog measured values