8i20 with 7i77/7i74 combo
- tommylight
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18 Nov 2017 01:29 #101956
by tommylight
8i20 with 7i77/7i74 combo was created by tommylight
Just to be on the safe side, after reading through the 8i20 manual i could not find any reference to 7i74, only 7i44, but as far as i know they are the same thing with the different host connector ( 7i74 25 pin, 7i44 50 pin ), or did i miss something?
The situation is that i need to change 1 drive ( or maybe 2 ) on a hurco BMC 20 with Yaskawa drives, but i do not like paying over 2000 euro a piece for 30 years old equipment for a lot of reasons. The motors on it are 0.85 KW AC on all axis, so using 3 x 8i20 would cost less even with the time and modifications required to make that work.
While i am at it, would a 7i80 work with two 7i29 and a 8i20 for a 4 axis and spindle system? I am fairly certain that it will, just need a confirmation.
A lot more questions but for now i will stop.
I am poised at using anything Mesa as much as i possibly can.
Thanx
The situation is that i need to change 1 drive ( or maybe 2 ) on a hurco BMC 20 with Yaskawa drives, but i do not like paying over 2000 euro a piece for 30 years old equipment for a lot of reasons. The motors on it are 0.85 KW AC on all axis, so using 3 x 8i20 would cost less even with the time and modifications required to make that work.
While i am at it, would a 7i80 work with two 7i29 and a 8i20 for a 4 axis and spindle system? I am fairly certain that it will, just need a confirmation.
A lot more questions but for now i will stop.
I am poised at using anything Mesa as much as i possibly can.
Thanx
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- bevins
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18 Nov 2017 01:36 #101957
by bevins
Replied by bevins on topic 8i20 with 7i77/7i74 combo
I am anxious to see how this turns out.
The only issue i see is the 8i20 is torque mode only. I did see a on of 8c20? for board that you can use velocity mode. Not sure but I am sure i read it. maybe 3C20.
I never used servo's in torque mode so I dont know how that would pan out.
The only issue i see is the 8i20 is torque mode only. I did see a on of 8c20? for board that you can use velocity mode. Not sure but I am sure i read it. maybe 3C20.
I never used servo's in torque mode so I dont know how that would pan out.
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18 Nov 2017 02:37 #101959
by tommylight
Replied by tommylight on topic 8i20 with 7i77/7i74 combo
"The 8I20 is a low cost 2200W 400V three phase torque mode/voltage mode
amplifier for synchronous permanent magnet servo motors (Brushless AC servo) up to
approximately 3HP. The 8I20 will supply peak currents of 30A."
That is a quote from 8i20 manual, meaning torque or voltage mode, as far as i could understand.
I read on this forum that torque mode is best set up with 2 PID loops for each axis, but i never did try that.
amplifier for synchronous permanent magnet servo motors (Brushless AC servo) up to
approximately 3HP. The 8I20 will supply peak currents of 30A."
That is a quote from 8i20 manual, meaning torque or voltage mode, as far as i could understand.
I read on this forum that torque mode is best set up with 2 PID loops for each axis, but i never did try that.
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18 Nov 2017 02:51 #101960
by bevins
Replied by bevins on topic 8i20 with 7i77/7i74 combo
This is from the mesa site:
Mesa site link for 8i20
For applications that require a smart amplifier, the 8C20 daughter card can be added. The 8I20/8C20 combination adds the features of analog input velocity and torque modes, step and direction mode, quadrature input mode, smart position control mode, and four isolated inputs and outputs.
I cant seem to find the 8C20 card anywhere.
For applications that require a smart amplifier, the 8C20 daughter card can be added. The 8I20/8C20 combination adds the features of analog input velocity and torque modes, step and direction mode, quadrature input mode, smart position control mode, and four isolated inputs and outputs.
I cant seem to find the 8C20 card anywhere.
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19 Nov 2017 03:21 #101990
by tommylight
Replied by tommylight on topic 8i20 with 7i77/7i74 combo
Just checked mesanet.com, mesaus.com, eusurplus.com, none of them have 8i20 on stock !!! I wonder when would they be available ??? PCW? JT? Filipe?
Andy, you have used 8i20, any tips?
Thank you,
Tom
Andy, you have used 8i20, any tips?
Thank you,
Tom
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20 Nov 2017 17:38 #102077
by andypugh
I haven't seen any need to use cascaded PID, but I do agree that it ought to work better.
You have Yaskawa motors. What type of feedback do they have?
Replied by andypugh on topic 8i20 with 7i77/7i74 combo
Andy, you have used 8i20, any tips?
I haven't seen any need to use cascaded PID, but I do agree that it ought to work better.
You have Yaskawa motors. What type of feedback do they have?
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20 Nov 2017 18:09 #102083
by tommylight
Replied by tommylight on topic 8i20 with 7i77/7i74 combo
5000 PPR incremental encoders with diferential outputs including index, 5V power supply so they are perfect for 7i77. There are no tachos.
As far as i understood from the manual, they can be used as is with the 8i20, but not certain. Could not find any more info on them aside form your youtube videos.
I would like to use another 7i?? That is a dual H bridge ( bigest one ) for a plasma cutter as i already have a 5i25/7i77 combo on it.
Double PID was mentioned on this forum, if i remember correctly.
As far as i understood from the manual, they can be used as is with the 8i20, but not certain. Could not find any more info on them aside form your youtube videos.
I would like to use another 7i?? That is a dual H bridge ( bigest one ) for a plasma cutter as i already have a 5i25/7i77 combo on it.
Double PID was mentioned on this forum, if i remember correctly.
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20 Nov 2017 18:29 #102085
by andypugh
Replied by andypugh on topic 8i20 with 7i77/7i74 combo
Any commutation feedback from the motors?
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20 Nov 2017 18:35 #102088
by tommylight
Replied by tommylight on topic 8i20 with 7i77/7i74 combo
No HAL sensors, nothing. Just 3 phase and encoder.
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20 Nov 2017 18:45 #102091
by andypugh
Replied by andypugh on topic 8i20 with 7i77/7i74 combo
The encoder probably does something clever at startup to give absolute position for commutation.
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