hart

[labnoob]

hi, all. was looking into building a basic app for the simulation of a flow control valve using hart comms. the hart coms terminates on a TRI loop, which then outputs a 4 - 20 ma analogue signal for the flow computer. the company i work for are supposed to be getting a FCV hardware for testing this loop, but could be some time. so i was just wondering if it would have been possible to design something with labview. i have Labview 8 with a usb 6008.


any ideas?


thanks.

[JamesC]

Hi Labnoob,

Can you tell me what/where/how you are going to measure?
Do you need to test current?

Also what accuracy are looking for? i.e what range V's, mV's, mA's and an approximate range 0-10 or 0-1.

Once I have this information I will be able to better answer your original question.

Regards
JamesC
NIUK and Ireland

[labnoob]

Not measuring mate.  More simulating. They say a picture is worth a thousand words, so here is a lame attempt to describe what’s basically going on. I would like to simulate a valve from my laptop. From closed (0%)  to open (100%) or at any point in-between, i.e. 30% open etc. I require to send this signal out from the laptop in the HART protocol, then the tri loop converter converts that signal to a 4-20mA signal, where 4mA would be the valve closed, and 20mA would be the valve open, 12mA would be at 50% open etc. I was just wondering if this is possible with Labview?

Is that any clearer mate?

[labnoob]

oh and, 4mA is at 1V, 8mA is at 2V, 12mA is at 3V, 16mA is at 4V, and 20mA is at 5V

thanks

[Ben]

I have read this all multiple times and I still am not following you.

I believe hart protocl was used with Brooks Smart MFC's....

but you appear to have some widget that talks hart.

So since I can not undertand what you are asking, I would like you to please try to clarify what you are trying to do.

Sorry for not understanding,

Ben

[labnoob]

ye, the tri loop takes a HART signal from the flow  control valve, then outputs a 4-20mA signal to the flow computer, 4-20mA being the sort of standard range for metering. the tri loop lookes like this, http://www.emersonprocess.com/rosemount/document/pds/333.pdf

did you see my diagram, did that not clear things up?

what i need to do is simulate a flow control valve (hopefully in labview) that outputs a HART signal to the tri loop. the tri loop converts that signal to a 4 - 20mA analouge signal which the flow computer understands.

[JamesC]

Hi Labnoob,

Looking at the data sheet for the rosemount, do you want to connect up to the Hart protocol Comm +- or Burst Input?

How do you want to connect your computer to the rosemount, via Serial connection transmitting Hart Protocol encoded packets, or by sending digital data from the 6008?

Regards
JamesC
NIUK and Ireland

[labnoob]

Hi, jamesC

I have a feeling it is Burst, but I will double check tomorrow. Yes, it may be useful to use rs232, most of our engineers have either a serial output on their laptops or have an USB  - RS 232 converter. We also have Adams modules which we could use to convert the 232 into 2 wire 485, i think that would work as an interface. that’s what we do for modbus comms anyway. im the only one with the USB 6008, but my boss would probably buy 4 or 5 if it was worth it. what do you think?

So are you thinking this can be done fairly easily with labview?. I only need to build a basic GUI, perhaps with a slider to control the valve (0 - 100%), and with a bit of guidance write some code for the comms.


Thanks again for your time on this,

LN

[labnoob]

just checked, defo Burst mode!

[labnoob]

details on the adam module.

http://www.amplicon.co.uk/dr-prod3.cfm/subsecid/10001/secid/1/groupId/11438.htm