PDA

View Full Version : G540 Current set resistors



blueseidboy
18-08-2010, 02:40 PM
I was wondering if anyone can help me with the current set resistors on my G540?
From what i can gather they are used to limit current to the motor but there is also a 3.5A max per channel anyway.
My x & y motors are rated at 3.5A. My z is rated at 4.3A so do i need to use a current set resistors or not? :confused:

Thanks,
Wayne

irving2008
18-08-2010, 05:23 PM
Hi Wayne,

The instructions for the G540 doesn't say you can't have a resistor so I guess you do need one. They are set up for an output current of 1A per kohm of resistance, so I read it as you need a 3.5kohm (3.3k + 220R in series). The limit of 3.5A is the maximum safe working limit for the stepper driver, I suspect it will actually go a little higher than that and if you leave the resistor off it will default to some value just above 3.5A, however that may not be a safe operating mode.

tumutbound
23-08-2010, 03:17 PM
The G540 has idle current limiting which reduces the current at idle to 70% of whatever has been set via the resistor value.
If there's no resistor, then current limiting is disabled.
End result is that without current limiting, the motors will run hotter.

blueseidboy
23-08-2010, 03:21 PM
Thanks Guys, I guess they are worth using then although its good to know there's no danger to motors / drivers until i get them sorted :tup: