PC Board Output

I have a problem I hope you guys can help with. I have a circuit board that is used to control an industrial washing machine. The outputs from the board are transistor and should be connected to a Variable speed drive. The machine I am working on has 5 motors for different speeds. (No I can't use 1 motor) The paperwork indicates the outputs are digital . Is there any way I can interface these with slave relays?
Thanks

Yes, depending on the current-switching capacity of the board output transisitors, you could use that output to drive a relay with the same coil voltage as the transisitor output. Solid-state relays may be the best type, because they usually require less current to power up.

do you have a diagram?
check if the transistors are 5 volt or open collector.
what voltage are the inputs of the VFD.