Converting V input/output from PID loop into Amps to send to a valve?

[UMN CEMS]

I'm using the PID toolkit to control the level of water in a tank.  I have a FP-AIO-600 to read voltage from a pressure transducer (process variable; 0-5V), which is then sent through the PID loop.  However, the AIO-600 only outputs current, which is the signal that's sent to the water inlet and drain valves (4-20 mA).  This means that the output from the PID loop is in units of Volts, but this needs to be converted to Amps in order for it to control the valves.  Can this be done using LabVIEW, or do I have to get a FP-AIO-610 that outputs voltage?

Thanks for the help!

[LV_Pro]

If you have a card that outputs what you need to control the valves then all you need to do is convert from one to the other. If it is a linear relationship then it can be done with an interpolation, an equation for which can be found in the math functions palette. If it isn't, but you have an equation describing the relationship then a formula node may be appropriate. Otherwise a lookup table, basically a 2D array, with elements representing the "input values" and adjacent elements representing the "output values".