MODBUS Comms with Micromotion MVD Sensor

[jack1]

Hello

Sorry, only just recieved your post.

Did you manage to get a routine to work? The one I posted in this thread was used in the end for the project and worked fine, it might have required a few mods, I can't remember, but if you still need some ideas let me know and I will try to help.

Jack

[karagory2]

This is an update in case anyone stumbles across this post. It deals with occasional data loss when communicating with a Micro Motion (Emerson) Coriolis flow meters.

The Modus register to actual measurement conversion VI “5 CH MVD READ.vi ‏26 KB” has a problem.

The problem occurs when the first byte of a Modbus register is hex 0. The “Number To Hexadecimal String Function” is not programmed include a fixed width of “4”. Thus, when sent to further processing, the string only contains 7 bytes instead of the required 8 bytes. This will cause random erroneous measurements.

I have attached an updated VI “5 CH MVD READ ver 2.vi ‏26 KB”; it will also work on a 1700 transmitter.

[karagory2]

Correction #1:

The problem occurs when the first 4 bits of a Modbus register sent by the Micro Motion transmitter is hex 0. The “Number To Hexadecimal String Function” is not programmed to include a fixed width of “4”. Thus when inverted and sent for further processing, the string only contains 3 -1/2 bytes instead of the required 4 bytes. This will cause random erroneous measurements.

[jack1]

Just come back to this after many years!

Do you have the modifed vi that you did a few years ago by any chance in LV 2014 ?

The one posted on the link is just the top level one.

Thanks,

John