HART communicator 275/375 for field instrument loop test
Thread Content
Today, my colleagues discussed a question: when performing a loop test on 275, does 275 itself control the circuit current to the specified value, or is it the field device that controls the circuit current to the specified value through commands? I think it’s the latter; the 275 is merely a communicator, and one that uses digital communication. It does not have the ability to control current on its own, but rather it sends commands to the transmitter to output a specified current. I wonder what everyone’s thoughts are.
That being said, it’s still necessary to find documents as proof~~~~
The loop test of a transmitter involves using the transmitter as a signal generator; the 275 device sends commands to the transmitter to supply a current signal to the circuit, thereby enabling circuit verification.
Facts are the basis; what’s the need for documents! If you perform a loop test and don’t press the exit button but simply remove the handheld controller, what will be the consequences? At this point, the instrument will remain at the current value you force it to output, regardless of any changes in the actual input value! ! Is the current still related to the manual operator at this time?
What was said on the fifth floor is correct; the handheld controller is merely a command device that does not provide any current output, but rather uses relevant commands to control the transmitter’s output. If you force the meter to output 20mA and then remove the handheld controller, the meter will continue to output 20mA; even though the handheld controller is no longer present, it will still maintain that output level. The solutions are: first, it is necessary to use the handheld controller to properly and completely terminate the test after it is completed; alternatively, the instrument can be powered off and then powered on again. Otherwise, the instrument will keep outputting 20
Can’t this prove it already? What more documents are needed as proof?
I’ve tried what you mentioned as well. I just told my boss directly that it had nothing to do with 275.
Come and learn* drop~ It sticks well! Thank you, OP!
Find a transmitter manual; it’s a document, and the instructions are clear there.
Ok, thank you. It’s just that our company is a bit rigid; our bosses don’t like to hear personal opinions and judgments – we need to look it up in the manual instead.