Hi. I'm fairly new to cnc world. I am building my own cnc router machine. I'm currently trying to wire up limit switches to the c10 BOB. I have NO/NC switches and I don't know if I require the use of a resistor or is there a resistor on the BOB. again, I'm a noob. Thanks
which version of the C10 breakout board do you have ?
a while ago I reverse engineered the C10 BOB from various photos on the net to produce this diagram
on the C10 a jumper connects the 5 input terminals via a 4K7 resistors to either +5V or ground
(so they act as either pull up resistors to +5V or pull down resistors to ground /0V)
with your limit switches connected between GND and the input terminals you need to put the jumper on +5V
its usually safer to connect the switches as N/C so a broken limit switch wire stops the machine
several switches can be wired in series so you only use one input terminal if you need to save the other four inputs for other uses ( E-stop , touch probe and MPG A&B outputs for example )
If you have conflicting requirements for pull up or pull down resistors by having switches that ground four of the inputs and one that connects an input to +5V
you can connect the C10 jumper to +5V so the on board 4K7 resistors act as pull up resistors on all inputs
then for the input with the switch to +5V you can connect a resistor of about 200 to 500 ohms between the input and ground
this low value of pull down resistor will over ride the effect of the on board 4K7 pull up resistor
John
note
if you have the C10S it uses one 74ACT245 to buffer printer port pins 2 to 9 instead of the two 74ACT245 IC's on the earlier C10
Last edited by john-100; 12-12-2017 at 07:16 AM.
Reason: add ref to C10S
The c10 BOB I have is revision 10.3. I plan to use two limit switches per axis. I guess the two the two limit switches per axis will be in series. So its best to wire limit switch to NC and have jumper set to 5v to pull up? I appreciate all the help so far.