Cincinnati Milacron Arrow 750 Retrofit

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26 Mar 2020 13:33 #161564 by stegrg
Hello Everybody,

I recently purchased a Cincinnati Milacron Arrow 750 from a local shop. The machine is equipped with Siemens Acramatic 2100 and was giving the original owner intermittent issues with both the controller and drives. The physical machine is still in good condition so I purchased it with the intention of retrofitting with Mesa hardware and Linuxcnc. I plan on running this machine in my garage so I'll be converting to single phase as well.

I'm currently in the process of stripping down the enclosure to gain access to switches, sensors, motors, etc... and to reduce the size for passage through my garage door opening.

I removed the z-axis motor and noticed that it's a Siemens 1FT6064-6AF71-4AB1. I looked up the specs for this motor and it has a 2048 1Vpp Incremental Optical Analog encoder.

Right now I'm considering going with the 5i25, 7i77, 8i20, and additional IO cards as necessary.

I'd like to keep and use the original 1Vpp encoder on each servo motor. What is the best way to interface the analog signal of these encoders to drive the 8i20 commutation? Do I need to convert the analog signals to absolute digital or is there a Mesa interface card that can directly process these analog signals?

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26 Mar 2020 18:10 #161588 by bbsr_5a
the 7i77 will read this signals fine SIEMENS runs as TTL
just check them by 5V and oszilograph if the index is ok
as you say this Motors like to break on index as on Hard stops

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27 Mar 2020 00:18 #161641 by stegrg
Does that mean the 7i77 will read the sin/cos signal from the Siemens encoder as TTL? Can that signal be used for motor commutation?

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27 Mar 2020 00:29 #161642 by tommylight
@stegrg
I do not think it will, but wait for PCW to confirm that.

@bbsr_5a
Confusing users, not good.

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28 Mar 2020 16:11 #161821 by andypugh

stegrg wrote: What is the best way to interface the analog signal of these encoders to drive the 8i20 commutation?


Possibly a Heidenhain EXE box.

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28 Mar 2020 21:01 #161838 by stegrg
Thanks for the suggestion.

I've searched through the forum a little bit and found that HAL needs the rotor angle to know which field winding to energize when starting to rotate after initial power up. Since the sincos encoders on these Siemens servers can provide initial rotor angle in analog, I would need to convert the analog signal to digital and feed that angle into HAL somehow.

Mesa sells the 7i80DB that (I believe) allows me to communicate to HAL via a SSI or BISS communication protocol. If I build (or buy) an interface that converts the analog signal to digital, can I use the 7i80DB to get a digital absolute signal to HAL to start rotating the servo?
Attachments:

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28 Mar 2020 21:17 #161841 by andypugh
Just about any of the Mesa FPGA cards can do SSI or BISS.

Are you in a hurry? The STMBL servo drive can use 1Vpp sin/cos input directly, and talks smart-serial back to a Mesa card and LinuxCNC.

However, the main power-IC that they use is discontinued so the STMBL won't be an option until a redesign is completed. And even then you would need to get some made as it is an open-source project.

Apart from not existing the STMBL is the perfect linuxCNC retrofit servo drive.

github.com/rene-dev/stmbl/blob/master/do...tting%20Started.adoc

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29 Mar 2020 16:59 #162003 by stegrg
Yes, I agree the STMBL driver would be the perfect fit but certain IC's are no longer available as you mentioned, and haven't been for a little while now.

Do you know if a redesign would be available in the next month or two? If not, I think the 8i20 and some 1Vpp sin/cos interface would be my next best option aside from Granite drivers which are a bit too pricey...

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31 Mar 2020 14:12 #162262 by stegrg
Does anybody know if the SPI interface on Mesa boards are fast enough to process rotor angle commutation? I found some TI online documentation that describes exactly what I'm trying to accomplish.

www.ti.com/lit/ug/tidua05a/tidua05a.pdf

I'm just curious if anybody has tried something like this and had success or insurmountable issues.

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31 Mar 2020 14:23 #162263 by andypugh
I have two machines running similar setups, though not exactly the same.

I have servos with resolvers that are commutated via HAL.

Resolver -> 7i49 -> PCI -> HAL -> bldc,comp -> HAL -> Smart-Serial -> 8i20 -> Motor.

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