Can anyone recommend a breakout board for use with LinuxCNC and a milling machine (3 or 4 axis)?
I’m intending to use separate stepper drivers.
Breakout from USB, Ethernet, RS485 or Parallel port?
With its own clock+command buffer+galvanic isolation for 5V supply or just breakout functionality?
Parallel or USB, not sure about the other points, hence looking for guidance.
Parallel the Gecko G540 seems to be very common but I consider the parallel port with timing generated in software on a PC to be the wrong aproach nowadays.
There are 3 and 4 axis USB cards on eBay for 20-40eur that have all the other 3 points.
In general USB cards are much better in terms of reliable timing and are not limited to a very small number of input ports.
They usually also generate PWM pulses to control a spindle if your spindle VFD can’t talk RS485 to the PC.
Gecko is working on an RS485 version of the G540 for ages now but hasn’t released any product so far.
Does LinuxCNC work with USB breakout?
Damn, your out of luck.
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?LinuxCNC_Supported_Hardware
“USB devices cannot be used to control motors or perform other “real time” tasks”
The ones I have seen so far only supply Windows drivers and MACH3 plugins.
No that’s good, I’ve ruled out a few options. So I’m looking for a 3 or 4 Axis board with Parallel connection. I’m tempted to try on of the £10 Chinese boards but in was hoping that someone could advise regarding their suitability or recommend a board.
I replaced one of them because it required a higher signal level then the +3.3V that are common nowadays and had optocouplers of different speeds for DIR and STEP.
The Mesa 5i25 + 7i76 combo isn’t cheap ($200) , but it is fully supported by LinuxCNC, and can handle 5 axes of steppers at 10Mhz step rates (generated on board) and also adds outputs to drive a VFD for the spindle and 48 24V-safe IO lines. For more money you can add a heap more IO on the second header. (for example a second 7i76, or 8 x 48 IO smart-serial boards)
I should have pointed out that the 5i25 is a PCI card, and needs a PCI slot. The 7i76 looks like it will plug into a parallel port, but in fact it won’t. (Well, it will plug in, but that is all it will do)
Thanks Andy. I will have a look at those.
I used KL-DB25 from http://www.kelinginc.net/BreakoutBoards.html.