Viper step dir drives for DC servos

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15 May 2017 14:05 #93226 by bevins
bevins created the topic: Viper step dir drives for DC servos
Has anyone tried the Larken Automation Viper 200 drives for DC Servos with LinuxCNC?

They look to be inexpensive, has a PID loop, and adjustment procedures and looks like it will be a good fit to my Bridgeport R2E4
I am retrofitting. Will use 5i25/7i76 and those viper 200 drives.

Would like to know if anyone has used them with mesa cards before.

www.viperservo.com/dloads/viper-manual.pdf

Bob
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17 May 2017 21:58 #93319 by andypugh
andypugh replied the topic: Viper step dir drives for DC servos
I don't know if anyone has used them, but they look like they should work fine.
However, I am not a huge fan of running servos with a step/dir interface.

Are the original servo-amps in the machine functional?
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18 May 2017 12:09 - 18 May 2017 12:12 #93336 by bevins
bevins replied the topic: Viper step dir drives for DC servos
Yes they are functional. I dont know for how long though. They are huge makes alot of noise, and I want to change them out. I sold this machine and dont want any comebacks.

You have any drives in mind that will run DC servois without step and dir?
Last Edit: 18 May 2017 12:12 by bevins.
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18 May 2017 12:12 #93337 by bevins
bevins replied the topic: Viper step dir drives for DC servos
Also have these in mind....

DG4S-16035
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21 May 2017 00:53 #93412 by andypugh
andypugh replied the topic: Viper step dir drives for DC servos

bevins wrote: You have any drives in mind that will run DC servois without step and dir?


The vast majority of DC servo drives work on analogue voltage velocity command. That's tricky from a parallel port (but not impossible) but LinuxCNC supports a lot of hardware that can control those drives.

There are drives that are controlled from PWM from both Pico and Mesa.
www.pico-systems.com/pwmservo.html

store.mesanet.com/index.php?route=produc...83_90&product_id=147 or store.mesanet.com/index.php?route=produc...83_90&product_id=141 (and maybe others)

There are also options that are purely digital. Mesa 8i20, STMBL, General Mechatronics
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21 May 2017 03:19 #93422 by jmelson
jmelson replied the topic: Viper step dir drives for DC servos

andypugh wrote:

bevins wrote: You have any drives in mind that will run DC servois without step and dir?


The vast majority of DC servo drives work on analogue voltage velocity command. That's tricky from a parallel port (but not impossible) but LinuxCNC supports a lot of hardware that can control those drives.

There are drives that are controlled from PWM from both Pico and Mesa.
www.pico-systems.com/pwmservo.html

Yes, our PWM system has both brush and brushless drives that take a PWM signal and direction. The PWM controller is connected to a PC by the parallel port, and has registers that are addressed and read/written by the LinuxCNC ppmc driver.
So, it reads encoder position, calculates a new velocity, and sends that out to the controller as a PWM duty cycle.

This gets rid of the software step generation, only requiring the position be read 1000 times a second and new velocity sent out at the same rate. The controller can accommodate encoder count rates up to 5 MHz.

Jon
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21 May 2017 13:21 #93436 by bevins
bevins replied the topic: Viper step dir drives for DC servos
I sold my bridgeport but i sold it retrofitted. I didnt want to make money, just wanted to get rid of it. Digging into the retrofit, i figured out i needed to change the drives because it would be tough to integrate with existing drives. So i have about 1,000.00 to buy drives and hardware for upgrading.

I dont know much about pico systems but would be willing tomtry pico, i figured mesa 5i25/7i76 with dc servo drives at 180 each and changing encoders 80.00 x3 will come close but a bit over the budget.

I want to stay away from using the parrallel port on the computer.
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21 May 2017 16:32 #93440 by jmelson
jmelson replied the topic: Viper step dir drives for DC servos

bevins wrote: I dont know much about pico systems but would be willing tomtry pico, i figured mesa 5i25/7i76 with dc servo drives at 180 each and changing encoders 80.00 x3 will come close but a bit over the budget.

Not too clear what this setup is. Assuming DC brush motors and 3 axes, the Universal PWM Controller and 2 brush PWM servo amps will cost $625. The optional spindle DAC is $50, if you want to control spindle speed through a VFD. Why do you have to change the encoders?

Jon
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21 May 2017 20:47 - 21 May 2017 20:50 #93449 by bevins
bevins replied the topic: Viper step dir drives for DC servos
They are the original SEM DC servos and I think they have brushes. Not sure, will check. I have VFD already setup working with original control so no ned top change that. Just have to drive three SEM 120VDC servos.

The encoders are only 250, I would want at least 1000, and quadrature.

You have an fpga card? I hate using Parrallel ports on computer.
Last Edit: 21 May 2017 20:50 by bevins.
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21 May 2017 21:24 #93450 by bevins
bevins replied the topic: Viper step dir drives for DC servos

jmelson wrote:

bevins wrote: I dont know much about pico systems but would be willing tomtry pico, i figured mesa 5i25/7i76 with dc servo drives at 180 each and changing encoders 80.00 x3 will come close but a bit over the budget.

Not too clear what this setup is. Assuming DC brush motors and 3 axes, the Universal PWM Controller and 2 brush PWM servo amps will cost $625. The optional spindle DAC is $50, if you want to control spindle speed through a VFD. Why do you have to change the encoders?

Jon


Can I run a 5i25-7i77 setup to drive your pwm servo amps?
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