Hart communication with labview

[ojb]

Hello

I'm working on a school project, where I'm using different types of flowmeters and ABB 2600T transmitter to measure the flow trough the pipes. The transmitter sends out a singal of 4-20mA depending on the flow. How hard is it to implement HART in labview? Like set upper and lower range value from labview?

I downloaded Brooks MFC. But I didn't understand how it works, and there was no user manual or anything like that. I'm very new to labview and HART communication in general. So I need to get it explained step-by-step. Not sure if I have take water over my head when it comes to my labview skills and the task I'm trying to solve.

I use NI9171 to measure the current. I have managed to read the current in labview. So I will manage to get the program to work without HART implementet. But it would look so much more professional.

Thanks in advanced. 

[nathand]

It's definitely possible, but requires an expensive HART modem. There's a sample project here: http://www.ni.com/example/31203/en/ I'm sure you could implement your own HART modem with the right NI board, but that's a lot of effort for little gain. In my opinion, if the only reading you need is the one provided by the 4-20mA loop, I'd stick with the simple analog reading. In fact, that's exactly what I did on a work project recently. The system has 2 pressure transducers that supply an analog 4-20mA signal and support HART, and since all we needed was the pressure measurement and we already had an analog input board, the choice was easy. I don't think there's anything unprofessional about this approach.

[peternemanic]

Hello

i would need exactly the same as member ojb.

I'm using cRio9066, hart modem Amtec AM-9898 HART cRIO Module and flow meter ABB water master FEV111.

I would need to implement Hart. The are some examples from Amtec how to do that, but I can't read flow data.

How to modify attached AM_9898_HART_Scan_Devices_Example.vi to read flow data using HART protocol? (with current output 4-20mA is no problem).

Regards,

Peter

[mateh]

In the 9898 example project there's another VI called "multidrop example". You should be able to use the scan devices example VI to return the long address of your flow meter. Then you would enter the long address in the multidrop VI to read the primary variable, which is the flow data that coincides with the 4-20 mA output.

[peternemanic]

Thanks,

it is working. But one measurments takes aprox. 12sec.

Any idea how to make it faster - less than 1 sec.?

[mateh]

There are a number of reasons it could be taking longer.

The multidrop example VI uses a timed loop, and the default value of the Refresh Rate control is 10000 milliseconds. Have you tried reducing this?

Also, make sure that the address of your device is the first and only element in the array on the front panel. The other elements should be grayed out, otherwise the VI will attempt to read from those addresses (even if it is set to zero).

[dkentner]

I am having difficulty getting this example code to work... well, I can read the unique ID but not the process variable nor anything else. I know my device works as I have an example program from the manufacturer of the RS232-HART hardware that reads the process variable. Was there anything you had to tweak on the program to get it to work? For reference, I am trying to communicate with e Honeywell ST800 differential pressure transducer.