7i76 spindle control without encoder?

Hi All

I am at a stage where I want to run my 3 axis mill with basic open loop spindle control. I don't need synchronous spindle motion right now and just want to do some test cuts an generally prove things out a bit more.

I have a VSD 0-10V with direction and enable wired to TB4. This works in manual mode and spindle override seems to work but have not checked actual speed in detail.

If i run in MDI the spindle runs away to max speed - i guess due to the lack of an encoder signal.

I set up TB4 in PNFCONF as spindle, in subsequent spindle set up configured 0-10v over 2600 rpm, The remainder of the set up relates to encoder parameters. Is it possible to set up without an encoder?

Not sure how relevant but when I set up the board I set jumpers to TTL as I expected if I add an encoder at some point it will be single channel, single sided.

Any help greatly appreciated.

Ok so after a bit of sleep it turns out nothing much was wrong....

A combination of over thinking and not understanding the manual control in Axis UI (it's important use + /- buttons after pressing spindle start to get initial motion)

Somehow this lead me to accidentaly putting a stupid value in output_scale.Once corrected all is well

#********************
# Spindle
#********************
[SPINDLE_9]
P = 0.0
I = 0.0
D = 0.0
FF0 = 1.0
FF1 = 0.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 2600.0
ENCODER_SCALE = 1000.0
OUTPUT_SCALE = 2600.0
OUTPUT_MIN_LIMIT = 0.0
OUTPUT_MAX_LIMIT = 2600.0

I guess the answer to my question was open loop mode is indicated by FF0 = 1 and all other PID values = 0 - maybe this might help someone ......

Yes, if you have the PID setup so FF0= 1 and all other parameters are 0 the, PID component simply copies
the commanded value from input to output. I think pncconf does this to make it just a minor change to add feedback
control.

You can do open-loop control trivially without the PID, but if Stepconf puts a PID in there I can understand the reasoning.