BOB suitable for 3 axis+ B/C head build?

**marbles** · 20-07-2018

I’m on route with a new build but just realised the two different DB25 1205 breakout boards I have can give me enough pins for 5/6 axis but not enough for all the extra limit switches/ sensors that 3+B/C needs. I was planning to use a slave a stepper on the x axis, unless there is a suitable board for running twin x axis.

The Chinese DB25 boards are cheap but is there a good alternative with more pin out/in? I did see this which caught my eye.

https://www.aliexpress.com/item/CNC-...56383c00wtLs14

Any thoughts or link most welcome.

**Clive S** · 20-07-2018

With two DB25 BOB's you will have 10 inputs . The link you provided seems to give 12 input BUT that is at the expense of only using 3 axis. I don't think that you could use slave axis and 12 inputs with that board.

I have set up a system using two PP's with slaved homing and 3 mpg wheels 6 inputs, 2 inputs on X for the slaved axes, Y+Z 1 input and the other 1 input for for estop. Or get rid of one mpg it will free up two more inputs

**marbles** · 20-07-2018

Hi Clive,
Two db25 boards. Interesting! I guess I would need another parallel port card in the PC. I have one of the green cards like this and a blue one as second link so enough between these two.

Potentially a bit of a head scratcher though eh. Is the software side straightforward, assigning ports and pins etc?

https://www.ebay.com/itm/CNC-6-Axis-...-/121480961528

https://www.aliexpress.com/item/Upgr...001497211.html

....Update

Just thinking about it I could use the one of the BOB to run the 3 axis and the slave and the other BOB to run the B/A axis and secondary sensors.

I'm not that familiar with parallel port/db25 instruction. Can I daisy chain the two boards together or do I need to run a separate card to the second BOB?

Much food for thought

**Clive S** · 20-07-2018

I'm not that familiar with parallel port/db25 instruction. Can I daisy chain the two boards together or do I need to run a separate card to the second BOB?

Not sure what you mean by this. But to use two PP BOB's you will need to P ports on the pc. so you would need another PP card fitted and the two cables one to each BOB.

I have been using Linuxcnc for these simple jobs but it is a learning curve. I think Mach3 can take at least two PP BOB's then you would set them up in ports & pins. Plenty of vids on the net for that.

**marbles** · 20-07-2018

Cheers Clive!
Yeh i've just been reading up on the setting up Mach3 with two PP ports. Think its a case of getting lucky if you dont get a driver conflict on the installed PP card however it'll resolve what I want. I have the boards so might as well give it a go :)