Error Occurs When Using a Command 18 of HART Protocol

Updated Feb 25, 2020

Reported In

Hardware

  • AM-9898

Software

  • LabVIEW

Issue Details

Using AM-9898_HART_Multidrop_Example.vi, which is LabVIEW example of AM-9898, I started to develop a code of HART protocol using AM-9898. 
However, HART communication is failed with checksum error when I write Tag, Descriptor and Date through Command 18.
Is there any solution to solve this problem? Is this problem related to LabVIEW code or input data?

Solution

The problem failed to HART communication is related to LabVIEW code. You need to modify some part of code.

The request HART packet has the following structure:

As you can see above, Data locates after Number of data bytes. But in LabVIEW code, Data locates before Number of data bytes. You can check it in AM-9898_HART_Command_18_OUT.vi
 

The above picture is the block diagram of AM-9898_HART_Command_18_OUT.vi. As you can see, Data goes into second index and Number of data bytes goes into third index of Array. What you need to modify is swapping the order of Data and Number of data bytes. By changing the input order, you can solve the problem.

Additional Information

If you want more information of HART protocol, please refer to the below link.