5i23 + two 7i40 +7i37

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08 Sep 2017 12:40 #98677 by billykid
billykid created the topic: 5i23 + two 7i40 +7i37
hello.
i would like to use two 7i40hv with a 5i23, there is a driver to connect it one by one and the third by gpio?
regards
Mauro
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08 Sep 2017 12:53 - 08 Sep 2017 12:54 #98681 by PCW
PCW replied the topic: 5i23 + two 7i40 +7i37
Standard SVST4xxxx firmware should work, you need a funny flat cable with 3 connectors ( one connector goes to the 5I23, and two connectors go to the two 7I40s ) In this case you need to jumper one 7I40 for channels 0,1 and the other for 2,3. This leaves two 5I23 connectors free for GPIO use.

If you dont mind losing a 5I23 connector, you can use SVST8xxx firmware, connect the 7I40s individually
with two flat cables. In this case you leave both 7I40s jumpered for channels 0,1. Each 7I40 will only use 1/2 of the pins on each cable so you will end up with odd channel numbering in hal: encoders/PWMs 0,1 for the first 7I40 and 4,5
for the second.
Last Edit: 08 Sep 2017 12:54 by PCW.
The following user(s) said Thank You: billykid
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08 Sep 2017 18:55 #98707 by billykid
billykid replied the topic: 5i23 + two 7i40 +7i37
good
today I've been testing with a h bridge homebuilt and it works fine, I will order 2 7i40hv from the European distributor Monday.
for these cards what parameters should be set? I got good results with P160 and D 1.5 all the other zero. Strange that with D at 0 the proportional can not exceed 50 otherwise it oscillates.
however, I will resume with the new cards, maybe it's all different.
regards
Mauro
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08 Sep 2017 19:28 #98710 by PCW
PCW replied the topic: 5i23 + two 7i40 +7i37
With a bare HBridge ( voltage mode drive ) you will always need some D for best performance
In fact, the higher the D term you can use, the higher the P that's possible.

Also with voltage mode you should use FF1 to compensate for the motors Back EMF
This is tuned by looking at the following error with a low P term and adjusting for minimum lead or
lag at say 1/2 full speed.

After this is done you can add a bit of FF2 to compensate for lead/lag during accel/decel

All tuning must be done under actual load, tuning a bare motor is hard to do and pretty useless

Also if not already done, you should connect the PID components feedback-deriv pin to the encoder velocity pin
for the least noisy D term

When all basic tuning is done you can add I until it oscillates then use about 1/2 the value where oscillation starts
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09 Sep 2017 08:46 #98723 by billykid
billykid replied the topic: 5i23 + two 7i40 +7i37
Thanks Pcw
always precise answers!
one last thing .. now i have a 1024 cpr encoder. since it is not differential, I wanted to replace it with
HEDR-55L2-BY09 line driver + index 3600 cpr .. same shaft 8mm.
will I have any problem with the oscillations?
which cpr number is appropriate for these cards?
regards
Mauro
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05 Oct 2017 18:49 #99969 by billykid
billykid replied the topic: 5i23 + two 7i40 +7i37
i have already tried two 200 w motors and they go very well for y and z axis, now i have a doubt about the x motor ... i'm afraid it's too big 90 volt 7 amps.
however it is going with the servodrive I have now, 75 volt power supply
if I leave current limitation 5 amps I can use it?
it does not need much power, I used that because I had it and it has a 14 mm shaft
I attach the motor data
regards
mauro
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