Do I need a BoB when replacing a parallel port connection with a UC300 or UC400?

[Doddy]

For clarity, OP mentions a controller, previously connected to desktop. To OP, that “controller” IS a BoB. My earlier suggestion is to retain that as your Bob rather than replace. A-Camera is correct, you need a form of Bob, whether that legacy equipment or as a functional block on an integrated system? Such as the AXBB)

Just to contradict the last post. The (stepper) driver normally provides the optical isolation, rather than the BOB but the BOB typically provides the optical isolation for the sensor inputs. All good stuff.

Some BOBs do provide optically isolated outputs to the (stepper) drivers, absolutely. But I’d suggest 95% (random number, guess) of the enthusiast grade machines will have optical isolation within the driver, and adding it also to the BOB is not required (and can be detrimental)

Best thing is, get a photo of your control box and will give you a list of conflicting advice and options to play with :-)

[A_Camera]

The (stepper) driver normally provides the optical isolation, rather than the BOB but the BOB typically provides the optical isolation for the sensor inputs. All good stuff.

Some BOBs do provide optically isolated outputs to the (stepper) drivers, absolutely. But I’d suggest 95% (random number, guess) of the enthusiast grade machines will have optical isolation within the driver, and adding it also to the BOB is not required (and can be detrimental)

Be aware that many drivers also implement optical isolation the wrong way, so in reality, even if there are opto couplers on the driver PCB and they claim optical isolation, it does not mean that it provides protection when needed. I tried to google documentation about the driver the Op mentioned but I failed, so I have no idea how it is actually built.