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IndustryArena Forum > CNC Electronics > Servo Motors / Drives > ServoStar CD amplifier for CNC router
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Results 21 to 38 of 38
  1. #21
    Join Date
    Dec 2006
    Posts
    31
    I called the local distributor and as I expected he doesn't know anything about that.
    He's going to ask about and give me prices and delays.

    For info: http://www.atb-automation.be/index_F.html (site on french or dutch)

    I think that the suitable converter is the following:
    http://www.elmomc.com/support/manuals/PL_UG_1102.pdf

    Technical Specifications
    Pulse and direction input interface:

    Feature Details
    Input type Optically-isolated
    Frequency range 0 - 2 MHz
    Input voltage 5 V ≤ Vin ≤ 9 V

  2. #22
    Join Date
    Jun 2003
    Posts
    125
    WOW, I totally missed that Elmo actually sells a S/D converter dedicated to this use. That's awesome!! Oh, and my next servo drive purchase will be from granitedevices. His hardware is by FAR are the best bang for the buck. Most drives in this price range are 100% analog while the VSD series are digital with a slick computer interface.

  3. #23
    Join Date
    Dec 2006
    Posts
    31
    Update about pulse dir converter.

    I asked several days ago for a quote and delay at various distributors in Belgium and France. Actually these bloody peoples aren't able yet to give me a quote they told me that the product doesn't exists and were literally making me a liar....Until I gave them the link, .pdf and explanation about the products they should know something about...
    (I work for an industrial distributor so I know what I'm talking about...)
    :withstupi
    Anyway, i have to wait for a quote until they think about it...
    Furthermore, they told me that it's an obsolete product, it was a part of the old sales program. We'll see.

    I think I gonna look for same solution but different way.

  4. #24
    Join Date
    Aug 2007
    Posts
    558
    Hi Jerome and CNCAddict,

    I'm very interested in your discussion as I also have a couple of sets of the Servostar amps and DDR motors.

    Could I suggest another possible option for your comment? Use a Smooth Stepper board - it will output a much higher pulse rate, giving you more speed without losing resolution. The Smooth Stepper will also output a Quadrature signal (use gearing mode 3 on the Servostar drive), which might help you avoid the voltage divider antics...

    CNCAddict - I agree 100% on the Granite Devices drives

    Best regards,

    Jason

    Edit - I missed post 12, which makes this post redundant... Oops, sorry guys.

  5. #25
    Join Date
    Jun 2003
    Posts
    125
    Jerome. That sucks about the Elmo...if they are discontinued then we really only need to find one of them to see what chips they use to do this function. Probably not too hard to replicate for our purposes. I'd much rather buy one though.....

    Jason, I'm actually using the smoothstepper with the kollmorgen drives. The problem is that I have the smoothstepper connected to my CNCbuildingblocks breakout board to convert to differential...but CNCbuildingblocks is no longer making products. I believe the smoothstepper will only output single ended no matter what output mode it's in....so there will need to be some sort of conversion process to get it working with the kollmorgen. Differential signalling is really an industry standard. It's very strange that we can't easily find a product that can do this. My feeling is that we're just not looking in the right place.

  6. #26
    Join Date
    Dec 2006
    Posts
    31
    Hello,

    I'm on the way to find something. I don't know when but yesterday I found something related in texas instruments documentation. The problem is: I was on a extrnal PC and I cannot retrieve the document. I'm searching for to re-read it.I think this document is a nearly good approach. With the actual setting (divider + capa) it's not working well, the quadrature signal have two levels per channel. When we use pulse/dir system we do not have a cycle which maintains highs and lows. Or we need to configure the cycle time in the motors settings...(mach3). But it's not intended to build a quadrature signal since it's constant setting and not frequency dependant. So it'll be really hard to have a full quadrature signal, that means step or data losses.
    My thoughts here above are not sufficient/true to have the full picture about the problem but one thing is sure, it's not the right way.

    Any ideas or solutions are welcome,

    Jerome

  7. #27
    Join Date
    Dec 2006
    Posts
    31

  8. #28
    Join Date
    Dec 2006
    Posts
    31
    Hello,

    Maybe that could be a good approach.

    This site also contains interesting informations, have a look.

    http://pico-systems.com/stepdir.html

  9. #29
    Join Date
    Jul 2007
    Posts
    22
    Quote Originally Posted by CNCAddict View Post
    Hmmm,... If you can't get the voltage divider circuit working then it may be possible to find a chip that will convert single ended to differential....
    Hi, not sure I understand all you talking about, but may be this quote from Granite Devices documentation (see page 8) will help : " Encoder connector
    This is a connector for quadrature encoder with differential line driver (26LS31 or equivalent). Single-ended encoders without inverted (-) outputs are not supported directly. 26LS31 conversion chip can be
    used to interface to single-ended encoders."

  10. #30
    Join Date
    Dec 2006
    Posts
    31
    Hello Oleks,

    I know well granite devices drives I personally have 3 of them.
    But in fact we are discussing about pulse and direction signals conversion to differential quadrature signals.
    Maybe could you help us to find something matching our needs.
    Important things:
    Frequency bandwidth an delay.
    see earlier posts.

    Jerome

  11. #31
    Join Date
    Dec 2006
    Posts
    31
    Hello,

    I received the answer about Elmo converter.
    First, the German manager told me that it's no more available. Maybe there's some old stock because I received a quote from France and they gave me this :
    Price 100€
    Shipping and handling 50€

    I think it's a bit expensive...
    Let me know what you think about,

    Jerome

  12. #32
    Join Date
    Aug 2007
    Posts
    558
    It does sound a little expensive, especially the shipping. Mind you, if you need it badly enough, it's well worth it!

    Would the quadrature output from a Smooth Stepper not work for you?

    Regards,

    Jason

  13. #33
    Join Date
    Nov 2007
    Posts
    4
    Hey guys, just to let you know, as per Appendix C2 of the install guide on the CD Series drives, single ended pulse / direction is fully supported. 5V TTL logic
    Pin1 = Pulse
    Pin3 = Ground
    Pin4 = Direction

    Don't worry about differential input, that is only for encoder input. I don't think the CD even looks at the differential pins in P/D mode.

    Let me know if it works out for you.

  14. #34
    Join Date
    Jun 2003
    Posts
    125
    The difference is the input frequency. Any high speed/high resolution application needs to use the differential input.

  15. #35
    Join Date
    Nov 2007
    Posts
    4
    Actually, yes and no...

    The speed of the application has little to do with single ended or differential inputs to the drive. It has to do with noise immunity. I am making a few assumptions here, but bear with me, i have been doing motion control / industrial automation for roughly 20 years so i am basing my opinion on experience.

    If you were interested in having your motion controller (parallel mach3) at the max length possible (50' if memory serves me correctly, you may have a small issue with noise, but in more cases impedance and voltage drop will be your bigger enemies. In the vast majority of applications the cable is roughly 10' long from the computer to the drive. Shielded cable with one end grounded at the drive end will most likely suit you well. Assuming your single ended to differential adapter using parallel port connections and you still come from your computer to your dirve enclosure (10' cable) then run through a single to differential converter, only to run 8 inches to the drive, you are pretty much just throwing $xxx hundred dollars away. Now if you mount the differential adapter at the computer, or ideally have a true output card controlled by mach3 that has true differential output, then you may see a lower signal to noise ratio at the drives, and even possibly a lower risk of missed steps due to noise / voltage drop / impedance, but very little. You would more likely to be using the extra functionality that comes with a single to differential adapter which is the line driver capability. Most encoders are relatively low voltate / low current devices which suffer at long cable lengths (50' +).

    Differential outputs are primarily used on encoders that are motor mounted, and have cable lengths that are run in close proximity to motor leads and other noise emitting cable sets.

    Try going single ended, keep cables as short as possible, keep them away from motor lead wires, use shielded cable (no exceptions), a ferrite core at one end or both of the parallel cable ($2) with a full loop through the core, and daisy chain the pulse / direction wires outside of your cable track / panduit, etc. when going from drive to drive.

    When all is said and done. disable the drive and have Mach send a full speed pulse signal (rapid) and check the signal / pulse train for noise with a scope. I don't think you will be dissapointed.

  16. #36
    Join Date
    Jun 2003
    Posts
    125
    Sorry, I was referring to C3 (2.5khz max) and C8 (3mhz max) inputs. The C3 connector has very limited use in CNC applications.

    http://www.danahermotion.com/website...ingcontrol.pdf

  17. #37
    Join Date
    Nov 2007
    Posts
    4
    Yes, you are right on that one....Almost a waste of space putting that feature on the C3 connector based on input speed, but it would allow for simple multiposition interface, albeit crude for PLC applications without the need for a TTL card to drive C8 inputs.

  18. #38
    Join Date
    Sep 2010
    Posts
    1765
    c8 is diff input only; if u send only single ended into it, it will not work. but u sometimes can get by with single ended if u put voltage divider from +5 to low input then to ground; ie., 1k resistor +5 to c8 pin 2 and 1k from pin 2 to common. ditto for pin 5. this gives 2.5v constant voltage to low diff input and as single ended goes from 0 to 5v it will switch. had one job this worked with another it did not.

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