but the author (as always on a forum) never gives the thumps up for what he/she did, that actually works.
This board offers effective, state-of-the-art, reliable linear control of HVAC 4-20mA dampers and valves. The CONVERTER-VMA420 voltage to current converter is a signal control (Proportional) 4-20 mA voltage to current transducer board for HVAC (Heating, Ventilation and Air Conditioning), electro-hydraulic and servo electronics; actuator, dampers, bleed pilot valve, globe valves, butterfly valves, plug valves, dampers and more. The CONVERTER-VMA420 board is designed to perform voltage to current conversion (transducer). If used properly, it will eliminate the need for an expensive board, which would otherwise be needed to carry out the same tasks. The CONVERTER-VMA420 is easy to install, setup, and operate. If you want to do professional remote voltage measurement related functions, The CONVERTER-VMA420 offers the features you need. It can be mounted easily via two 0.125" mounting holes using 4-40 screws. Simply connect the board to 24VDC or 24VAC connect your voltage source 0-10V to the input and our board will convert it to 0-20mA. For input voltage 2-10V the output current is 4-20mA. The CONVERTER - VMA420 transducer board is an accurate, linear, and an efficient way to convert industrial standards voltage (input DC voltage models) 0 to 10V, 2 to 10V, 0mV to 1.2V, 66mV to 1.2V, 0mV to 2V, 400mV to 2V,0-5V, 1 to 5V, 0-15V, 3 to 15V, 0-24V, 4.8 to 24V into industrial standards (output current float on 16-20V DC) current 0 to 20mA, 4 to 20mA signals.... See below table "voltage to current industrial standard configuration models".
I have read this post like 10 times,