Question on instrument calibration please?

[IdealDan]

Hi Friends,


Please, I need clarification on two things:


1. I understand trimming via Zero and SPAN adjuster, BUT what MENU on Emerson 475 Field Communicator is used for Trimming?


2. For 475, Do I need to physically introduce 250-ohm Resistor on the Positive side of the the Loop? I was told that 475 has in-built 250-ohm Resistor that eliminates the need, is this true?


3. How do one differentiate between HART and FIELDBUS Transmitter?


Thanks in advance

 

[cardosocea]

1) What is trimming in Instrumentation terms?

2) Did you read the manual? The leaflet mentions this resistor as a spare part, so chances are that it isn't included and came in the box with the communicator.

3) HART runs on a 4-20mA loop and modulates digital data on top of the analog signal. A fieldbus is a digital communication protocol which will run on whatever media was defined for it... RS232, 422, 485, Ethernet, etc, etc...

 

[danw]

The device model/part number is different for HART or Foundation Fieldbus.


The quick way is whether the transmitter is 4-20mA or some digital signal.


HART is 4-20mA. Digital is Foundation Fieldbus or Profibus.

 

[IdealDan]

1) What is trimming in Instrumentation terms?

2) Did you read the manual? The leaflet mentions this resistor as a spare part, so chances are that it isn't included and came in the box with the communicator.

3) HART runs on a 4-20mA loop and modulates digital data on top of the analog signal. A fieldbus is a digital communication protocol which will run on whatever media was defined for it... RS232, 422, 485, Ethernet, etc, etc...

Hi Friend,
Sorry if I'm wrong, by Trimming I mean: assuming with my calibrator I input the LRV of Psi expecting a 4mA output from the Transmitter and found out that deviates, how do I make adjustment using 475 (not 0 & span button)? What menu on 475 please?

 

[danw]

There is no 'standard' menu for HART devices.


Menu navigation depends on the specific device, which is manufacturer-specific. You need the manual that covers the HART calibration method for that device.