mesa 7I29 compatible anything i/o cards
- edscrane1
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01 Dec 2012 08:12 #27109
by edscrane1
mesa 7I29 compatible anything i/o cards was created by edscrane1
Thank you for all the help provided in my last topic.
Mesa cards seem very good value. If I use 2 x Mesa 7I29 dual H Bridge cards to drive the SEM 3nm dc servo motors, what is the best combination of cards to connect to the computer ( using Linux ) ?
On my mill, the x and y axis use glass scales for position and the z uses a rotary encoder on the motor.
Where does the tacho feedback go back in to the card?
Thank you again for any help and advice. If I get this right, the next project is a Harrison M300 needing a control and crosslide or turret, but lots to learn first.
Mesa cards seem very good value. If I use 2 x Mesa 7I29 dual H Bridge cards to drive the SEM 3nm dc servo motors, what is the best combination of cards to connect to the computer ( using Linux ) ?
On my mill, the x and y axis use glass scales for position and the z uses a rotary encoder on the motor.
Where does the tacho feedback go back in to the card?
Thank you again for any help and advice. If I get this right, the next project is a Harrison M300 needing a control and crosslide or turret, but lots to learn first.
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- PCW
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01 Dec 2012 11:53 - 01 Dec 2012 11:55 #27111
by PCW
Replied by PCW on topic mesa 7I29 compatible anything i/o cards
a 5I20 is a good choice here.
Do you know the current rating of your motors and the motor power supply voltage?
the 7I29 is rated 22.5A peak per Hbridge and 180V max
The 7I29 is a simple HBridge and has no tachometer inputs,
however the function of the tachometer can be replaced by the encoders
since the encoder counter hardware under LinuxCNC has good velocity estimation.
This will likely only work well if you have rotary encoders or very near
0 backlash on your scales however.
Forgot to ask: Do your linear scales have quadrature out?
If they are old enough they may be sine/cosine out and need an interpolator
Do you know the current rating of your motors and the motor power supply voltage?
the 7I29 is rated 22.5A peak per Hbridge and 180V max
The 7I29 is a simple HBridge and has no tachometer inputs,
however the function of the tachometer can be replaced by the encoders
since the encoder counter hardware under LinuxCNC has good velocity estimation.
This will likely only work well if you have rotary encoders or very near
0 backlash on your scales however.
Forgot to ask: Do your linear scales have quadrature out?
If they are old enough they may be sine/cosine out and need an interpolator
Last edit: 01 Dec 2012 11:55 by PCW.
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- edscrane1
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03 Dec 2012 07:52 #27131
by edscrane1
Replied by edscrane1 on topic mesa 7I29 compatible anything i/o cards
I think it is time for PLAN B.
I was hoping to use new drives but it is looking much easier to get the old drive card repaired.
I believe this should allow me to use mesa 5I25 and 7I77 cards ( the same control as the Bridgeport series 1 project by dembedded)
Hopefully I can follow this previous project to help work through mine.
I was hoping to use new drives but it is looking much easier to get the old drive card repaired.
I believe this should allow me to use mesa 5I25 and 7I77 cards ( the same control as the Bridgeport series 1 project by dembedded)
Hopefully I can follow this previous project to help work through mine.
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- andypugh
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03 Dec 2012 21:24 #27139
by andypugh
I am not sure why Pete is suggesting the use of encoder-velocity, as the existing drives are happy with the existing tachos, and if you swap to mesa drives then they don't expect tacho feedback.
Swapping the tachos to encoders might be necessary if you switch to the 7i29 as the motor and the linear scales are a bit "mechanically distant" from each other.
Looking at your website you look like a very handy chap to know
Replied by andypugh on topic mesa 7I29 compatible anything i/o cards
Possibly, though it may be something of a gamble on them staying repaired.I think it is time for PLAN B.
I was hoping to use new drives but it is looking much easier to get the old drive card repaired..
I am not sure why Pete is suggesting the use of encoder-velocity, as the existing drives are happy with the existing tachos, and if you swap to mesa drives then they don't expect tacho feedback.
Swapping the tachos to encoders might be necessary if you switch to the 7i29 as the motor and the linear scales are a bit "mechanically distant" from each other.
Looking at your website you look like a very handy chap to know

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04 Dec 2012 00:14 - 04 Dec 2012 00:15 #27145
by PCW
Replied by PCW on topic mesa 7I29 compatible anything i/o cards
I mentioned the velocity estimation because you can do OK with the 7I29s
without any tachometer feedback since LinuxCNC Encoder velocity estimation is a good velocity signal for the PID loops D term which replaces the external velocity loop. However, if you can fix the existing drive, that would simplify things.
without any tachometer feedback since LinuxCNC Encoder velocity estimation is a good velocity signal for the PID loops D term which replaces the external velocity loop. However, if you can fix the existing drive, that would simplify things.
Last edit: 04 Dec 2012 00:15 by PCW.
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