Modbus Error Message

[terryaharris]

I am trying to communicate w/ an Allen-Bradley Powerflex 700 VFD.  I am getting the following alarm message

"modbus exception response 2 -- function code 16 (start=4448, count2)"

What does this mean?

[Ryan.S]

The function code 16 is for writing multiple registers. In your case, it is writing 4448~4449. The error 2 means either the start address 4448 is wrong or the count 2 is wrong or not supported. Go to the Modbus object's property, click "Advanced", find the parameter "Preset regs". Set it to 1. Let's see if it works when you write one single register each time. You should also consult the AB for the Modbus error. As lookout gets the exception code 2, it means the PLC recognize the message, but doesn't support it.

[Fluid_Tester]

I am looking for a LabVIEW driver to communicate with a PowerFlex 750 Series Allen Bradley VFD.

Where should I look?

Having no luck so far!

Thanks! 

[Ryan.S]

Does this device support Modbus?

NI has a free LabVIEW Modbus Library

https://forums.ni.com/t5/Reference-Design-Content/LabVIEW-Modbus-API/ta-p/3524019