educa wrote:I searched the manual, but cannot find how low 1 PPI pulse takes ? Usually this is around 3ms, but how much is it on the DSP board ? And it is configurable ?
Here's what I've learned:
- PPI can be enabled or disabled. If disabled, laser is on continuously.
- If enabled, 50 PPI is the minimum (enforced after you hit "ok", so you might not notice)
- Duty cycle of the laser output is always 50%, regardless of pulse rate
- PPI is not "pulses per inch". It is pulses per distance, and mostly scales linearly with speed.
- It does not scale linearly with the PPI setting. It does go up and down vaguely with PPI setting, but there must be other limits. For example, at 25.4mm/s (1 IPS) and 1000 PPI, I got 333 PPS instead of 1000. But setting 500 still gave me fewer (not straight cap at 333) and 250 gave me fewer, but not half as many.
- Pulses can get much shorter than 1ms. I didn't try to find the limit, but I saw frequencies >2.5kHz, and duty cycle is always 50%.
The good news is that I was able to bump my top speed and acceleration for my X axis way over what I could get on my PC with linuxcnc. I had to bump my current over what was recommended in the E5 hookup diagram, but that's pretty generic. I don't really know what the pololus were set to, because the tiny pot on those boards is inscrutable.
(Since I had the scope hooked up anyway, I looked at the laser drive signal while engraving, and it looked nonsense to me, but I have yet to let the E5 actually fire the laser)
- OUT1 seems to be an active high (5V) laser output (so just inverse polarity of the laser TTL signal)
- OUT2 seems to be an active high (5V) "job in progress" signal. It doesn't activate for manual movement or laser firing, but stays high for the duration of a job.