Mesa 7i43 + 7i29 (x2)

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01 Sep 2010 22:15 #3953 by BigJohnT
Replied by BigJohnT on topic Re:Mesa 7i43 + 7i29 (x2)
That is pretty much the connections except there are 3 +-10v to your drives but I know by now that you know that.

If your spindle has an encoder you can connect that to the 7i33TA and have rigid tapping etc.

John

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02 Sep 2010 10:51 #3956 by KennyC
Replied by KennyC on topic Re:Mesa 7i43 + 7i29 (x2)
Thanks, good to know I'm on the right track.

I often see the 7i37 mentioned in the same breath along with the 5i20 and 7i33. I get the 7i33 - it converts the PWM to +/-10v signals - but what is the 7i37 used for? Why would I need it?

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02 Sep 2010 11:32 #3957 by andypugh
Replied by andypugh on topic Re:Mesa 7i43 + 7i29 (x2)
The FPGA boards can source or sink only 25mA per channel, and can be damaged by voltages above 5V. The 7i37 optically isolates the FPGA board and provides 1A @ 48V output switches and 24V-safe (and AC safe) inputs.

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02 Sep 2010 14:08 #3959 by KennyC
Replied by KennyC on topic Re:Mesa 7i43 + 7i29 (x2)
Ah ok, so in my simple setup of only driving 3 servos, I won't need it. But if I start using GPIO that needs higher current/voltages, I will. Makes sense.

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03 Sep 2010 19:42 #3972 by KennyC
Replied by KennyC on topic Re:Mesa 7i43 + 7i29 (x2)
We tested one of the cards, and long story short, we're going to go ahead and replace the original drives with Mesa 7i29s. We just don't know enough about the very old original drives to feel comfortable with them, and Baldor is unable to produce documentation that far back. That's good news for Peter anyway! ;)

Anyway, now that we're proceeding, we're at another crossroads. We basically have two configuration options:

    Option 1

http://yeup9g.bay.livefilestore.com/y1pXzW417MAZZ6vj9tTOb86B4lVutFmNYJvD9iGKsOgGxpTlbQoauXvo67bfdpaq6egH7kk_cBMTKYsRkLnXJwL8lDTZs_DKG--/option1.png?psid=1

Advantages
- power and logic are physically separated
- use original driver mounting locations near power supply
Disadvantages
- long data cable length (6-8 feet)


    Option 2

http://yeup9g.bay.livefilestore.com/y1p0XM8zq1Fx5g19LS_gMhXcODjkswdZuo9m1YlVJR7rDXJy7e11vKFYRI9fKjbpAkpkVineWp-KLxbJud1Yde4iiz0-TMB_SSH/option2.png?psid=1

Advantages
- very short data cable length
Disadvantages
- power and logic no longer separated
- +100VDC PWM cables run near encoder cables


Anyone have any thoughts as to which is the better way to go?

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07 Sep 2010 08:55 #4026 by andypugh
Replied by andypugh on topic Re:Mesa 7i43 + 7i29 (x2)
Option 2 is fairly normal, and ought to work. The voltage of the motor lines is less important than the current as far as EMI is concerned.

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