Hi All,
The following statements come from a post on the CNC-Zone forum. I need help accomplishing the first statement in this post as I don't have a clue even after reading enough to choke a mule on the subject. Although I did learn some other useful stuff in the adventure I wasn't able to answer the first step in this post. Maybe someone with more brains than I have can help me out in this one hopefully. Or at least tell me it can't be done in Mach3.
The software workaround: 1) make sure that the Mach3 signal level is such that when there is no step, pin 5 of the TB6560 (named CLK in the datasheet) is low. 2) Use 1/2 step Sherline mode, with kernel running at 25 or 35 kHz. The effect of Sherline mode is that the pulse will stay high for the entire duration of the kernel cycle, and reset on the next cycle. 3) Set the Direction pulse timing to the maximum (15 us - note the GUI indicates 1 to 5 but it will accept up to 15). The net effect is a long pulse (40 us for 25 kHz kernel, 28.5 us for 35 kHz), with the limitation that the maximum pulse rate is reduced to one half of the kernel frequency. This is not a problem given the fact that in any case the TB6560 maximum allowable step frequency is only 15 kHz.
The hardware workaround: replace R4 to R9 with lower value (470 or 1k). This will make the rising edge sharper and gain some pulse width margin. You can't go too low with the value, otherwise the falling edge will become too slow, reducing the margin. You still need to make sure the Mach3 signal level is as in point 1 above. You can then either use Sherline mode as above, or normal mode. In the latter case, just make sure both step and direction timings are set to their maximum (15 us) and don't exceed 35 kHz (there is no point and all it will do is reduce your pulse times, this eating the margin)
The statement labeled number one is the puzzle for me in this. I have been unable to figure out how to accomplish what the author is saying in Mach3 about keeping the signal low to pin five in it. I have already tried a number of different solutions to my problems with the machine losing steps but at this rate it is beginning to look like a replacement controller is in my future if no one here can help me in this.
Thanks in advance,
Lindsey
Guest
