Eding CPU5A4E controller and Siemens G110 VFD.

[EddyCurrent]

Now I see why you mentioned the solid state relay. Personally I would not be connecting the TOOL output directly to the vfd, I would attach a relay between TOOL and GND on the CPU (looks like you would need an external 24V supply), then I would connect the Normally Open contacts of that relay between vfd terminals 6 and 3 (then the vfd would have to be configured by it's firmware so that the input meant RUN FORWARD.
The main reason for using a relay, and it's the same with PLC outputs, is that it's easier and cheaper to change a knackered relay than it is to replace a knackered controller or PLC, etc. Volt Free contacts as they are called is the way to go for me. For similar reasons I would not be using the 24V supply from the vfd to drive a relay, it only supplies 50mA max.