New build with recycled parts on a ridiculous budget 120cm*60cm work area

**Desertboy** · 23-09-2017

Originally Posted by Neale

Another opinion...

5 BOB inputs is just enough. I'm assuming you are using microswitches here - it gets a whole lot more messy if you want to use inductive sensors. All limit switches and home switches can be wired in series to one BOB input except the X slave home switch which must have its own input. I would only use one X limit switch, BTW - that should be fine. One input for touch plate. One input for estop and fault signals in series. This is because a motor stall fault needs everything to stop fast before the gantry gets twisted sideways. And there's still one input spare!

If you really wanted, you could take the Y home switch to the spare input. This buys you the ability to simultaneously home X and Y to save a second or two during homing. I've done that on my machine just because it looks neat but it's hardly essential.

I'm afraid I don't know how slave axis homing works with LCNC - I switched to Mach3 from LCNC before slave homing became available.

I would take 5V to the 5V input terminals. The 12-24V input is for a separate PSU and you would need that to use the 0-10V analogue output for VFD speed control. Otherwise the BOB can't generate enough output volts from the 5V supply - common problem with 5V BOBs.

Thanks, that makes sense I'm going to have 2 mini towers next to each other one with a pc in it and the other with the PSU, AM882's and BOB so I can get 12v easy from the pc. In fact it's the same hassle to get 5v as 12v.

**Clive S** · 23-09-2017

I would take 5V to the 5V input terminals. The 12-24V input is for a separate PSU and you would need that to use the 0-10V analogue output for VFD speed control. Otherwise the BOB can't generate enough output volts from the 5V supply - common problem with 5V BOBs.

Neale As I understand it the 12-24v is also required for the inputs as well. I don't think the inputs work without it. (could be wrong though)

**Desertboy** · 23-09-2017

Originally Posted by Clive S

Neale As I understand it the 12-24v is also required for the inputs as well. I don't think the inputs work without it. (could be wrong though)

Do you mean the limit switches? I wonder if they work like on an arduino/ramps combo with pull up resistors (Which you can toggle on/off) I know the inputs from the microswitches are 5v on the arduino as I had to use resistors to get the 12v from the inductive sensor down to 5v so I didn't fry the arduino and disable the pullup resistors. But when you use microswitches you have pullup resistors enabled and wire direct.

I do have an inductive probe that works reliably at 5v but running at 5v's reduces the detection distance so I would use a chunkier probe at 12v if I go this route.

I think though decent quality microswitches fitted properly will have high enough accuracy I wouldn't see a difference in real world performance.

**Neale** · 23-09-2017

Plenty of people use microswitches, and that will probably be fine. I use inductive sensors, as much as anything for convenience in mounting, but in practice I doubt that you will have any issues. The other point is that once you start wiring inductive sensors in series to share a single BOB input, you need to make sure that you have enough volts to drive them as there is a bit lost in each sensor in the chain. I'm putting this crudely and hoping that the experts will let me off this time!

Do you have a pointer to any documentation on the BOB? My guess is that it will work fine with just a 5V feed. However, I doubt that the inputs have pull-up resistors as they are probably opto-isolated and pull-ups are a little bit trickier in that case. It's not like the Arduino where you connect directly to the input pins on the CPU chip. On the plus side, it's a bit more difficult to blow up a BOB than an Arduino! I strongly suspect that if you connect the switches (just one, or a number of them in series) between +5V and the BOB input, it will work fine, but I wouldn't guarantee that without looking at the documentation for the BOB, or even a sample "this is how you wire it" diagram.

**Desertboy** · 23-09-2017

Originally Posted by Neale

Plenty of people use microswitches, and that will probably be fine. I use inductive sensors, as much as anything for convenience in mounting, but in practice I doubt that you will have any issues. The other point is that once you start wiring inductive sensors in series to share a single BOB input, you need to make sure that you have enough volts to drive them as there is a bit lost in each sensor in the chain. I'm putting this crudely and hoping that the experts will let me off this time!

Do you have a pointer to any documentation on the BOB? My guess is that it will work fine with just a 5V feed. However, I doubt that the inputs have pull-up resistors as they are probably opto-isolated and pull-ups are a little bit trickier in that case. It's not like the Arduino where you connect directly to the input pins on the CPU chip. On the plus side, it's a bit more difficult to blow up a BOB than an Arduino! I strongly suspect that if you connect the switches (just one, or a number of them in series) between +5V and the BOB input, it will work fine, but I wouldn't guarantee that without looking at the documentation for the BOB, or even a sample "this is how you wire it" diagram.

There was no documentation with my quality £3.30 (Delivered) BOB from China lol I found the pinout online for an identical board.

https://warp9td.com/images/BOB_Vendo...line/ST-V2.pdf

I have tried to tight ass my build but only semi successfully lol.

**Clive S** · 23-09-2017

Originally Posted by Desertboy

There was no documentation with my quality £3.30 (Delivered) BOB from China lol I found the pinout online for an identical board.

https://warp9td.com/images/BOB_Vendo...line/ST-V2.pdf

I have tried to tight ass my build but only semi successfully lol.

For those that are interested I can confirm that the bob in question does need both 5V and 12-24v to get it to work.

Also when say 12v is applied I can also confirm that the input pins are pulled high so that a simple switch to ground will be fine.

**Desertboy** · 23-09-2017

Originally Posted by Clive S

For those that are interested I can confirm that the bob in question does need both 5V and 12-24v to get it to work.

Also when say 12v is applied I can also confirm that the input pins are pulled high so that a simple switch to ground will be fine.

You are THE MAN!!!

**Neale** · 23-09-2017

If that's the right doc for the board (sure looks like it!) then what I said above is correct, but connect one end of switch (or set of switches in series) to ground and other end to input pin. That's what the diagram in the doc is doing. Nothing will break if that's wrong, it just won't work. But I'd be pretty sure that connecting to ground is ok.

**Neale** · 23-09-2017

Originally Posted by Clive S

For those that are interested I can confirm that the bob in question does need both 5V and 12-24v to get it to work.

Also when say 12v is applied I can also confirm that the input pins are pulled high so that a simple switch to ground will be fine.

Clive - the doc says "12-24V optional". I'm pretty sure that I've seen someone else talking about a similar BOB where 5V supplied the board but there was no analogue out without the extra supply. But it could have an internal regulator supplying 5V if you do use the higher-voltage supply, I guess. Docs on this Chinese stuff are a nightmare! Personally, I'd start with the 5V connected to the +5V terminal and begin testing. My first BOB was a ZP5A which was broadly similar but no analogue out, so haven't played with the one in question. OP has 5V and 12V available so at least it won't mean an extra PSU either way.

**Clive S** · 23-09-2017

Originally Posted by Neale

Clive - the doc says "12-24V optional". I'm pretty sure that I've seen someone else talking about a similar BOB where 5V supplied the board but there was no analogue out without the extra supply. But it could have an internal regulator supplying 5V if you do use the higher-voltage supply, I guess. Docs on this Chinese stuff are a nightmare! Personally, I'd start with the 5V connected to the +5V terminal and begin testing. My first BOB was a ZP5A which was broadly similar but no analogue out, so haven't played with the one in question. OP has 5V and 12V available so at least it won't mean an extra PSU either way.

Hi Neale I have one of these bobs that I have been playing with linuxcnc and mpg's It fooled me at first. but I have just fired the bob up from a usb port for the 5V result nothing on the input pins. then I applied the 12-24v and hey presto volts on the input pins.

edit: there is a red led, lit when the 12-24v is applied it is next to the input pins