(Solved) acorn PLC programming change. For dyn4 servo spindle control.

[Pete Rondeau]

Hey Marty,
I understand the theory of the resistor, as I mentioned we use them on Mitsubishi drives on a daily basis. I'm just saying that there is no discernible difference whether it is connected or not.. Doesn't even get warm. Granted, I'm not constantly cycling the motor on and off which is when the heat would be generated. But most importantly, it didn't prevent the error..
I mean maybe?? it gave me a bit more leeway before faulting, but it still faulted.

I actually wired the DYN4 encoder output to Acorn and that works fine for what it is, but none of my ratios are currently 1:1. in high range it is 1:2 and then the rest are lower than 1:1

I'm thinking if I swap the existing step pulleys for timing pulleys, I'll have enough room to sneak in an encoder.

I understand the attraction of trying to go directly from the motor, but I just don't trust it, plus I'd like to tap on a lower range where it will have more "grunt".

Pete

[tblough]

Heat is not going to be generated cycling on and off. It's going to be generated when the drives are decelerating. If you have long decel time configured, then not much heat will be generated. If you have lot's of inertia and short decel times, then a lot of energy will need to be dissipated and that is where the braking resistors come into play.

[Pete Rondeau]

Yeah, like when I turn it off.

[martyscncgarage]

Hey Marty,
I understand the theory of the resistor, as I mentioned we use them on Mitsubishi drives on a daily basis. I'm just saying that there is no discernible difference whether it is connected or not.. Doesn't even get warm. Granted, I'm not constantly cycling the motor on and off which is when the heat would be generated. But most importantly, it didn't prevent the error..
I mean maybe?? it gave me a bit more leeway before faulting, but it still faulted.

I actually wired the DYN4 encoder output to Acorn and that works fine for what it is, but none of my ratios are currently 1:1. in high range it is 1:2 and then the rest are lower than 1:1

I'm thinking if I swap the existing step pulleys for timing pulleys, I'll have enough room to sneak in an encoder.

I understand the attraction of trying to go directly from the motor, but I just don't trust it, plus I'd like to tap on a lower range where it will have more "grunt".

Pete

It will only get warm when the drive dumps energy to it...if DMM says it won't do anything so be it.
I DO know I had to use one on the DYN4 drive on the Z axis of the FADAL mill I retrofitted. It had no counterweight, when jogging down it would fault.
DMM suggested the resistor, faults went away. Along with a Line Reactor, the machine seems to run great.

Marty

[SpacedmanSpiff]

Dear Marty,
The way it was explained to me was the Dyn4 drive has a voltage dissipation mechanism that is active while the drive is enabled. What we found was that the stock plc was disabling the drive on spindle stop thus disabling the built in system.
All the best
Sean.
Ps I will be 1:1 on my spindle drive when it is all together and will be exploring the tapping ability....

[Bhouin]

I have the 750w 880 servo/dyn4 on my lathe. I get a similar issue with an over voltage condition it I stop the servo from 2250rpm or greater. Works fine when the servo is running less than 2000 or so. I put the logic in above but when I look at the plcdetective I see that the spindle/servo faults before the timer expires to set the vfddisable. I put a service question into DMM about a brake resistor. I have 2 other options I have are to modify the output Gcode to ramp down the spindle speed prior to the m5 or modify the pic to do the same when an m5 is hit. Any initial thoughts on a PLC change? I need to do some investigation on the vfd speed variable

[Bhouin]

I reached out to DMM and they asked me to change a few parms. Max accel reduced and torque filter constant set to 64. For me I am using this setup as a lathe spindle. I went this way for 2 reasons, 1 is that it had a Chinese servo/drive that I was having issues with and space.