Run the VFD under by 4-20ma or either use the converter from current to voltage then make the VFD run by that setup…
Use vfd 0 to 10v or 4 to 20 ma.check this terminal parameters in vfd manual…set para 0v to 10v vfd function(inverse setting)…connect transmitter o/p 0 to 10v to drive …pressure increases…speed decrease,vice versa