MODBUS Comms with Micromotion MVD Sensor

[jack1]

I am having problems with occasional data loss when communicating with a Micromotion (Emmeson) Coriolis flow sensor model CMF010. The sensor uses an MVD module that allows communication via RS485 and Modbus amongst others. The Vi attached is used to monitor the Temperature and Flow values from the sensor.

When run, the data displayed in say Temperature, will drop to zero every 20 or 30 seconds before going back to its correct value. The same thing occurs with the other values being displayed but not usually all at the same time. Also noticed that it became worse when this vi was run in parallel while loops with other routines. Could there be a problem with the data not being ready hence a zero result is sent back from the flow sensor transmitter?

The RS485 signal is converted to RS232 before going through an PXI 8420 Serial board and this hardware setup has been checked using the Emmerson software 'PROLINK' where it worked fine with no instablity.

[Former NI Employee MS]

Hi Jack,

Are you still facing this problem ?

Regards,

[jack1]

Hello Mathieu

Yes the problem is still there but narrowed down to the following error codes 6101 and Framing error 1073807253. I have just done another post modbus error code 6101 and framing error asking  if anyone has had problems with these codes.

Thanks

Jack

[fernando.martinelli]

Hi Jack!

I have been trying to use your mod bus vi but there is one subvi missing: "Micro Motion_Hexidecimal - Floating Point ver2.vi"

Could you please save it under version 8.0 and post it?

That would really be a helping hand!

Thanks a lot,
Fernando

[jack1]

Hi Fernando

No problem, please find Vi attached. I found this Vi from a posting on the forum a while back and modified it for my example so claim no rights for it.

It was used if I remember in a routine that used the Visa Vi's rather than the NI Modbus ones, both versions worked ok for me but still get corrupt data every few minutes. Resorted to filtering the invalid values out, which although is not ideal has bought me some time to try and find out why the data has errors. Micro-motion have suggested adding pull down resistors on the RS485 lines so off to try that!

Back to the software if you need any more info let me know and see what I can dig up,

Jack

[fernando.martinelli]

Hey Jack!

I am sorry to bother you again but I have version 8.0 and could not run your vi that is on version 8.5.

No problem if you cannot save it under version 8.0 and publish it again, but I would appreciate that either way.

Donc vous êtes français? D'où venez vous en France? Moi j'ai vécu pendant un an à Toulouse, où j'ai fait un stage chez Airbus.

La France me plaît beaucoup, je pense fort à y revenir très bientôt!

Salut et merci encore!!

[jack1]

Hi Fernando,

Should be version 8.0 if that's ok

Jack

[fernando.martinelli]

Perfect!

Thanks a lot!

I guess you didn't understand a word of my french message? I thought you were french by seeing your profile description: "location France".

Never mind 😃

Have a nice weekend!

[jack1]

Hi Fernando

Sorry about that.

Yes I understood your French (which is a lot better than mine I might add!) but missed reply from last posting. At the moment living in Brittany, northern France, but in the process of relocating my business and family back to the UK next month.

So going through the pain of moving machines and equipment whilst tying up those never ending loose ends. Enjoyed our time out here but nothing ever stays the same when it comes to work!!

Have a good one,

Jack

[Searles]

Hello there,

I'm in the process of doing the same thing, setting up a MicroMotion flowmeter with LabView via the Modbus protocol.  I'm not too familiar with Modbus or VISA, did you happen to find a solution?

Thanks!