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

[Doddy]

Okay, I take it back. That's a new configuration for me. But the advice still stands - you can connect the UCx00 easily enough (though options to incorporate into the physical enclosure are a bit more limited). If that big PSU is a 24V DC powersupply for the board then why not slave the power from that?

[ian823478]

Doddy, good idea re the power supply. Doing that wouldn't create any risks of earthing loops would it? I only ask cos I had a nightmare when I first built this kit with steppers twiddling randomly while I watched. Turned out to be entirely due to my ignorance in that I thought I was doing a better job by earthing both ends of the shielding on the stepper cables
Edit: bugger. Power supply is 27V, just enough to exceed 24V max for UC400!

[A_Camera]

Okay, I take it back. That's a new configuration for me. But the advice still stands - you can connect the UCx00 easily enough (though options to incorporate into the physical enclosure are a bit more limited). If that big PSU is a 24V DC powersupply for the board then why not slave the power from that?

Well, that's not entirely true... The UC300 and 400 needs some sort of a BoB, because you need to split the contacts. Doing that without any BoB is possible, and as you said, most drivers have optical isolators anyway, for for that, you don't need a BoB but you definitely need some way of splitting the signals and lead them to the right contact on each driver. So "easy" is a very wide word. With a BoB it is easy, but without it is not so easy.

[Doddy]

Well, that's not entirely true... The UC300 and 400 needs some sort of a BoB, because you need to split the contacts.

Ah, I think I see where our thoughts are not quite joined up - I'm talking (and I'm interpreting Ian's intent here) - of connecting the UCx00 to the 25 pin D-Sub connector on the control box, using the internal System 4C components that implement the BoB and the Driver electronics. NOT, taking the UCx00 device to connect direct to the drivers.

[ian823478]

Ah, I think I see where our thoughts are not quite joined up - I'm talking (and I'm interpreting Ian's intent here) - of connecting the UCx00 to the 25 pin D-Sub connector on the control box, using the internal System 4C components that implement the BoB and the Driver electronics. NOT, taking the UCx00 device to connect direct to the drivers.

Doddy, you have interpreted my intent correctly
So connection wise I think I'd only need a D-sub 25 pin connector to solder on to one end of my lpt cable.

I'm hoping you were meaning the main board 12V (12-24) supply for the UCx00 when you mentioned 5V.
I had realised the 12V board supply isn't rated highly enough for the UCx00, which is a pity.

Back in 2012 I did post on here a few times while I was trying to sort out the earthing faults, but it looks like that is a time that has been lost to internet history!

A_camera, sorry I didn't explain things more clearly . If I can manage it, I'll post the manual and assembly pdfs....
Here we go, at least they are on the site if anyone needs them..
Case Installation.pdfManual.pdf

Ian