2-10VDC to 4-20mA conversion with resistor

Hi,

I am working with a 2-10VDC output on a VFD and using a resistor to convert to mA.

We put a 500ohm resistor on the output per the VFD instruction manual, however I am now seeing that the mA is less due to the increased resistance from the Transmitter.

The 500ohms is the total loop resistance needed.

What is the internal resistance of the 2-channel transmitter, per channel, so that I can get the right transistor size?

its 249ohm
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