No, no PID at all for bed. Reprap PID is not actually "industrial" kind of pid at all, our reprap pid is actually implemented as calculation for pwm on-off times. The whole point is to avoid pwm, first thing that means to avoid PID for the bed. So, no PID at all. PID for bed is bad. Only bang-bang.
Normally bang-bang means simply on-off. When temp reaches setpoint +2C (hysteresis) it will switch off. And then when the temp reaches setpoint -2C, it switches back on. Thats all for bang-bang, its supposed to be simple. It will quite a couple of seconds for bed temp to change with 4 degrees, so the mosfet will actually switch very very rarely. Only every now and then, like 10 seconds apart, maybe even more, but something like that.
But, just saying, i dont really remember when and where, coz im old retard, but i do remember some settings like "maximum and minimum bang-bang- value .... xxx " which requires a value between 0-255 for pwm purposes for bang-bang. That means when its supposed to be switch on, it will pwm at max value, and when its supposed to be off, it will pwm at the lower value. And this kind of stuff basically defeats our purpose entirely. Because it still uses pwm, which is very bad for heated bed. So for example if you run into those kinds of settings, then choose minimum bang-bang to 0 and maximum bang-bang to 255. This will give no pwm at all. Zero means its full off, and 255 its full on, again basically no pwm at all. This is what i meant.
Normally bang-bang means simply on-off. When temp reaches setpoint +2C (hysteresis) it will switch off. And then when the temp reaches setpoint -2C, it switches back on. Thats all for bang-bang, its supposed to be simple. It will quite a couple of seconds for bed temp to change with 4 degrees, so the mosfet will actually switch very very rarely. Only every now and then, like 10 seconds apart, maybe even more, but something like that.
But, just saying, i dont really remember when and where, coz im old retard, but i do remember some settings like "maximum and minimum bang-bang- value .... xxx " which requires a value between 0-255 for pwm purposes for bang-bang. That means when its supposed to be switch on, it will pwm at max value, and when its supposed to be off, it will pwm at the lower value. And this kind of stuff basically defeats our purpose entirely. Because it still uses pwm, which is very bad for heated bed. So for example if you run into those kinds of settings, then choose minimum bang-bang to 0 and maximum bang-bang to 255. This will give no pwm at all. Zero means its full off, and 255 its full on, again basically no pwm at all. This is what i meant.