HART protocol with MSP430

What do you want to do?  "Speak" HART for hobby purposes?  Industrial?  Ex/Non-Ex?  Master/slave?

Do you have a hardware developer?  Are you the hardware developer?  Are you both hard/software developer?

Do you want to do HART-FSK or HART-C8PSK? Do you want to use an external HART-FSK modem chip?  Do you want to build a HART soft modem?

As a starter check http://www.romilly.co.uk/index.htm

H.

Hello HardyGriech,

I am trying to implement a project for industrial level.

I am a hardware and software developer.

I want to work on HART-FSK. Is it possible to work without any external chip or is it necessary to use external chip like DAC8760. Is there any other IC which would be feasible for me to work with?

How to start with it?

Regards,

Mitesh

Some more questions:  high/low volume?  HART master/slave?

If I were you, I would use an external HART-FSK modem chip.  Read on at http://www.romilly.co.uk/hmodems.htm.  Read the application notes provided by some of the chip manufacturers.

My personal (anti)recommendation: don't use the SMAR one, because it has (very) bad waveshaping.

H.

Initially I will be using it as a MASTER and for low volume and if verified I will be going ahead with slave also and for high quantity.

So presently I would be using it as a MASTER.

Thanks,

Mitesh

• get the HCF documentation
• follow the application notes from the modem chip vendors for the hardware, if you want to make life easier in the first go, buy one of the HART converters and use its HART interface
• get a working HART slave device and connect it to your master device
• send a fixed HART command request from your master to the slave
• check if there is an answer
• implement your HART master

have fun

H.

Hello HardyGriech,

Sorry I was stuck up with some other projects which were on very high priority. Now I am completely into this project so would like to continue with this conversation.

I would just like to explain my application and would like to ask some small querries to go ahead.

I want to make an HART Enabled Product. I already have 1 product which uses DAC8760 IC which is having a capability to be HART Enabled.

I have read in a specification of this IC that we need to give HART Input. Does it mean that I have to give HART signal from HART Communicator? Is there any other way through which we can give HART Input?

Do we need a PC software for any caliberation or to observe any output? Do we need to Design any thing such or is it available online? If available can you provide some links?

I have no clue about HART protocol Stack. Can you guide me up with the same?

It will be really helpful if you can solve few of my silly questions.

Regards,

Mietsh

To be honest, this all is not trivial.

My advice: go and get a HART specialist who gives you advice about the HW, HART conformance testing, HART stack and so on.

This is really not an issue which can be discussed in this extent you are asking for.

Hardy

Hi Mitesh!

I hope you have a lot of time for this project :-) I have developed industrial process transmitters that work with HART Revision 7. It is much work until it is perfectly running. But when it works it is a damn good thing - I really like it!

The Romilly page, Hardy mentioned, definitely gives you a good overview about HART, but you won't be able to build a complete solution from that information. You need the official HCF documents when developing an industrial product. And there are a lot. And there are a lot of tests you have to go trough if you want to sell your product under the official HCF HART approved sign. These tests will cost much as well as the documents from the HCF - normally you sign up at the HCF as a member and will get access to all documentation.

The pre-tests can be done by several service providers, but buying the official HART Test Kit is almost cheaper and you can test your device after each code line without hoping everything works fine at a test center - let me tell you: It will definitely not! That produces more and more costs. And of course you need things like oscilloscope, function-generator and so on.

I've successfully used the smar HT2015, but I would not use it again since there are other chips like the DS8500 from Maxim which I would prefer nowadays and the HT2015 is damn expensive. The HART-ICs convert a UART signal to a wave shape with a frequency of 1200 or 2200Hz that is superimposed onto the current loop and vice versa. I would not recommend trying to build something waveshaping on your own as these chips are made for that.

What I definitely can recommend is the HARTTools and the FrameAlyst from Borst Automation:

http://borst-automation.com/downloads/downloads.htm

There is also a trial version - this helped me a lot during developing.

Dennis

I would not use the Smar HT2015 too:

• needs "unusual" clock: expensive crystal with 460.8kHz or oscillator with prescaler required
• there is a problem with the waveshape of the output signal. Despite sayings in the data sheet it does not output a HART compliant FSK signal. Instead it outputs square waves which require additional filtering on the output side.
  This was a least true for the HT2015 version we used

Hardy

Yes, the 460.8kHz crystal is a weird thing - there is almost no supplier for that. But I didn't use the crystal. I clocked the HT2015 from the micro. I used a 3.6864MHz system clock and divided it down to 460.8kHz (binary divider of 8). A precise time base is very important for HART. The documentation of the HT2015 is pretty awful, too. I didn't get along with the circuitry shown in the datasheet - I had to change some things. The output is kind of a squarewave, that is right. But this is not unusual for the modem-ICs. There must be a type of output-filter...anyway...on the current-loop you will see kind of a sinewave.

Yes, the amplitude of the two different frequencies vary a little bit, but as long as they stay inside the allowed window, this is OK.

I don't know about HCF_Spec-054 yet, but I will have a look at it.