4-20 ma HART Transmitter

G

Thread Starter

gct

Is 4-20 ma analog card of transmitter damaged because hart communicator is showing only 4 ma but it should show 12 ma as per process value.

Note:
transmitter is connected to 24vdc terminals (1 n 2)
and anal0g 4-20 ma also connected to 24 vdc as 4-20 ma loop require (terminal 3 n 4 )it as per manufacturer.

awaiting your kind reply
 
Without knowing what the function of terminals 1, 2, 3 and 4 are, it's not possible to determine what a wiring problem might be.

But you should be aware that 2 wire, loop powered transmitters only have have DC power on 2 terminals, not 4 terminals. Is your transmitter a 2 wire, loop powered transmitter?

One thing that can hold a HART transmitter's output to 4mA is when the HART polling address is something other than address zero because the transmitter thinks it is on a HART multidrop network.
 
R
Adding to David

It could also be the loop is not set up with the proper Voltage or load. It will only draw the right current if the Voltage can overcome the loop resistance.
 
H

Heinrich Baumann

> Is 4-20 ma analog card of transmitter damaged because hart communicator is
> showing only 4 ma but it should show 12 ma as per process value.

Please clarify, do you mean the process value is 12 mA, which means the output of the transmitter is 12 mA?

> Note:
> transmitter is connected to 24vdc terminals (1 n 2) and anal0g 4-20 ma also connected to 24
> vdc as 4-20 ma loop require (terminal 3 n 4 )it as per manufacturer.

When the current is 12 mA and the HART communicator shows 4 mA this probably means the HART communicator is not connected correctly. The HART communicator shall allways be connected over a load, either on the side of the PLC/DCS or the transmitter.

Further: Can you read the configuration of the transmitter? Is there a display on the transmitter? What output does the display show?

Hope this helps
Heinrich
 
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