Hey Mike,
yes, of course, 13 (RS385 A) and 14 (RS385 B). You got to have them connected to 485+ and 485- on the VFD (I linked you to the exact I/O port docs above).
But you don’t know where did you read that? Pins 15 (“tool enable”) and 16 (“tool direction”) just switch on and off a non-VFD spindle. Pin 15 (“tool enable”) is used by many users for a relay to switch their hand trim router on and off.
Your VFD however is also able to be controlled by these pins. You could use that as a fallback solution if you cannot get the ModBus communication to work. In the Onefinity Controller, you would choose “PWM spindle” as “tool type” and wire pin 15 (“tool enable”) to one of the programmable multi-function inputs of your VFD and the Onefinity Controller would be able to switch on and off the spindle by g-code commands or by a g-code program, similarly as it would if connected over the ModBus communications port. As for spindle speed, it could be controlled by pin 17 (“tool PWM”) if you buy a PWM-to-Control-Voltage converter and connect it to the 0-10 V analog speed input of the VFD. You got to program these ports and modes accordingly inside your VFD. This is described in your VFD manual.
By the way, this analog control voltage is the way how the MASSO CNC Controllers control a VFD, since MASSO controllers don’t have a ModBus communications port 
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One user reported the problem (which persisted) was with the DB-25 connector soldered into Onefinity Controller Mainboard, and where the problem could only be resolved by resoldering the solder joints on DB-25 connector pins on Onefinity Controller Mainboard .
Unfortunately some users reported in the past they did not get the ModBus connection to run at all. This exclusively applied to cheap chinese VFDs though. There can be many reasons why it fails, some of them can be found, others not. However I encourage everybody who wants to run an induction motor (=spindle) on their CNC rather than a hand trim router that sets your workshop on fire 