Build a BOB

[djreiswig]

I have a C&CNC Ethercut controller (Mach3) and I noticed that it only uses 1-1/2 of the 3 available ports on the smoothstepper board. I've read all of the info I can find, but still have questions. I've tinkered with some basic electronic projects, but I'm no expert.
I'm wondering what I would need to build a second BOB to utilize the extra ports. I've read about BOBs and I'm still not sure what is required to build one. Do I need optoisolation, pull up resistors, pull down resistors? An external power supply, or is the built in one sufficient to power some relays? What type of relays?
I know there is also a concern with relays switching before Mach is loaded. I think there is a workaround to keep this from happening, but I don't recall where I read it.
For right now I'm just wanting to add a couple more relays, but who knows what else I may dream up in the future.

[acourtjester]

Simple thing to do is contact Tom C at CandCNC, I would guess he will pick this up as he also posts here

[djreiswig]

I didn't want to bug him. He has enough things on his plate. I thought for sure with all the creative people here, surely someone has built a BOB.

[tcaudle]

All our newer controls (LINUX/CommandCNC) have expanded opto isolated inputs (16) expanded motor (axis) outputs (up to 8), and expanded relay drivers (up to 10) New EBOB is a direct Ethernet BoB (No other interface card) and all of the buffers for inputs /outputs and direct DTHC 5 socket is standard. We continue to support the older obsolete MACH3 systems but we are not doing any further development or expansion of those systems, You can hang another BoB on the port3 of the ESS card and use the ESS Config and the MACH Config to get access to the added I/O. The BoB can have relays to give you more power outputs.

[djreiswig]

Yeah, I'm wondering what I would need to do to build said BOB.

[tcaudle]

About 39 bucks. Any simple single port Bob should work. They are everywhere. most have lots more outputs than inputs. Some have one or two power relays.

[djreiswig]

Okay, since I'm not getting much input on actually building a BOB, maybe an off the shelf solution would be better. So I'm looking at a CNC4PC C52- ESS THIRD PORT EXPANSION BOARD
And connect a C36 - Quad Relay Board to it.
Next question is will I have issues with the relays doing funny stuff while Mach starts? I've seen some boards with an enable pin to lock things down until Mach has control. Is this an issue with the smoothstepper?

[tcaudle]

Why would you spend 50 to 100 man hours designing and building a BoB when you can buy one for 39 bucks? The CP (Charge Pump) SHOULD (on most BoB ) keep all outputs OFF . THe ESS will pass that signal but its up to the BOB itself to lockout the outputs if its not present. Another BoB off another port probably will not have a CP inhibit function of if it does you will need to make sure it hooked up and provisioned in the Outputs in MACH3. There are two CP outputs in MACH3 and you can assign them to two different PORTS and pins.

[djreiswig]

I got nothin' better to do.
I've been talking to Andy at Warp9 and I think I'll get a simple BOB and a relay board with optoisolation. Is there a 12v dc source in the Bladerunner box that I can use for the relays? I see the ones on the i/o board are 12v. If not, I'll have to get a wall wart.

[tcaudle]

There are multple 12V sources. The main bias supply is referenced to the circuit ground and can be used to drive the coils of relays but make sure they have suppression diodes on each coil or you can thow a spike back onto the 12V that could take out things you don't want to lose.
The 12V on the Table I/O is the floating for the inputs and if you try to use that it opens up all of your inputs to noise. There is a 12V feed to the two relays but NOT a 12V common there because the relays coils are pulled to common (low) from the driver circuits. Do not try to pick up the 12V from there.

[djreiswig]

Okay. Where would I find the main bias supply 12v you speak of?

[djreiswig]

Andy at Warp9 recommended I get a 5v relay board so I did. He says I need to power the relays from the same 5v supply as the ESS. Is the 5v supply okay to use to power relay coils? The relay board I have is opto isolated and has flyback diodes.
Or would I be better off with a 12v board?