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  1. #1
    I posted this in the General section before I realised there was a specialised stepper /servo section

    http://www.mycncuk.com/threads/13945...onnection-help

    I will try and get a mod to transfer it.
    Last edited by Nemo1966; 27-08-2020 at 07:10 PM.
    Every time I am wrong - the World makes a little less sense.

  2. #2
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 18 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,344. Received thanks 187 times, giving thanks to others 65 times. Referred 1 members to the community.
    Page 13 of the servo controller manual tells you all you need to know about the step/dir interfacing. It recommends a differential drive from the control system, but it's not required. You can use a standard single-ended drive - just connect Step/Dir to pins 6/8 and ground pins 5/7 (just check that - the scan isn't great). The internal 220R resistor is appropriate for 5V signalling.

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  4. #3
    Duplicate - sorry
    Last edited by Nemo1966; 28-08-2020 at 10:20 AM. Reason: duplicate
    Every time I am wrong - the World makes a little less sense.

  5. #4
    Quote Originally Posted by Doddy View Post
    Page 13 of the servo controller manual tells you all you need to know about the step/dir interfacing. It recommends a differential drive from the control system, but it's not required. You can use a standard single-ended drive - just connect Step/Dir to pins 6/8 and ground pins 5/7 (just check that - the scan isn't great). The internal 220R resistor is appropriate for 5V signalling.
    Thank you.

    A couple of things if I may?

    One thing that sort of confused me when i first looked at the diagram - twisted pairs? You mention connecting Step/Dir pins to 6/8 and ground to 5/7. The diagram is confusing, it shows a single pulse going in e.g Pulse A and it terminates on 6 - 5???

    Apart from where you cannot on the MB3 are the connections to the Sevo drivers the same? If using a single ended drive do i need to connect a 12 - 24v supply as mentioned on page 13? Do I need it for a differential drive?

    The MB3 supports both.

    Sorry for the basic questions - I just don't want to blow up the 200 MB3 breakout board.

    thanks again - the advice is appreciated.

    Edit: just found a better diagram (helps me understand) in the MB3 documentation:
    Click image for larger version. 

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    I added the pin numbers from the Panasonic doc, does that look correct? How can you tell that pins 5, 7 are ground? (the scan shows order from top down (6, 5, 8, 7) as per my latest attached diagram.

    Do I connect a dedicated 24v to pin 11+ and 28- ? For single ended? and not differential? Both or none?

    thanks again
    Every time I am wrong - the World makes a little less sense.

  6. #5
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 18 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,344. Received thanks 187 times, giving thanks to others 65 times. Referred 1 members to the community.
    Quote Originally Posted by Nemo1966 View Post
    Thank you.

    A couple of things if I may?

    One thing that sort of confused me when i first looked at the diagram - twisted pairs? You mention connecting Step/Dir pins to 6/8 and ground to 5/7. The diagram is confusing, it shows a single pulse going in e.g Pulse A and it terminates on 6 - 5???

    The differential lines are - not clear admittedly - intended to show the interconnect between your control system (MB3 in your case) and the servo controller.

    Quote Originally Posted by Nemo1966 View Post
    Apart from where you cannot on the MB3 are the connections to the Sevo drivers the same? If using a single ended drive do i need to connect a 12 - 24v supply as mentioned on page 13? Do I need it for a differential drive?

    The MB3 supports both.
    Ah, sorry, didn't realise the MB3 support differential drives. If you're taking the signal over any distance then a differential twist pair is beneficial for noise-rejection.

    Quote Originally Posted by Nemo1966 View Post
    Sorry for the basic questions - I just don't want to blow up the 200 MB3 breakout board.

    thanks again - the advice is appreciated.

    Edit: just found a better diagram (helps me understand) in the MB3 documentation:
    Click image for larger version. 

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    I added the pin numbers from the Panasonic doc, does that look correct? How can you tell that pins 5, 7 are ground? (the scan shows order from top down (6, 5, 8, 7) as per my latest attached diagram.

    Do I connect a dedicated 24v to pin 11+ and 28- ? For single ended? and not differential? Both or none?

    thanks again
    Click image for larger version. 

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    The bits circled in red - these are the LEDs of the opto-isolator inputs. The lead connected to the triangular bit is "+", the bar crossing the pointy bit of the triangle is ground. Hence - ground is 5,7 and the signal positive is 6,8. To the immediate-left of these are similar symbols, but reversed - these are normal (non-light-emitting) diodes intended to protect the LEDs from a reverse voltage as would be presented by a differential drive (LEDs are susceptible to damage like this).

    Also, confusingly, over on the left - the triangular line drivers - the bottom output wire has a little dot on it - denotes an inverted signal. So "PLUS A" (ignoring typo) is PULS - non-inverted (active = high), and "PLUS B" is PULS - inverted (active = low). You could interpret (wrongly) the cross-over in the wires as the wires swapping - that's not the intent of the diagram - it's supposed to show an indeterminate length of cable. The drawing is designed to confuse.

    EDIT:


    12-24V between pins 11 & 28 - these are required for the control inputs shown, nothing to do with step/dir but likely required to provide control to the driver.
    Last edited by Doddy; 28-08-2020 at 11:54 AM.

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  8. #6
    Quote Originally Posted by Doddy View Post
    The differential lines are - not clear admittedly - intended to show the interconnect between your control system (MB3 in your case) and the servo controller.



    Ah, sorry, didn't realise the MB3 support differential drives. If you're taking the signal over any distance then a differential twist pair is beneficial for noise-rejection.



    Click image for larger version. 

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    The bits circled in red - these are the LEDs of the opto-isolator inputs. The lead connected to the triangular bit is "+", the bar crossing the pointy bit of the triangle is ground. Hence - ground is 5,7 and the signal positive is 6,8. To the immediate-left of these are similar symbols, but reversed - these are normal (non-light-emitting) diodes intended to protect the LEDs from a reverse voltage as would be presented by a differential drive (LEDs are susceptible to damage like this).

    Also, confusingly, over on the left - the triangular line drivers - the bottom output wire has a little dot on it - denotes an inverted signal. So "PLUS A" (ignoring typo) is PULS - non-inverted (active = high), and "PLUS B" is PULS - inverted (active = low). You could interpret (wrongly) the cross-over in the wires as the wires swapping - that's not the intent of the diagram - it's supposed to show an indeterminate length of cable. The drawing is designed to confuse.

    EDIT:


    12-24V between pins 11 & 28 - these are required for the control inputs shown, nothing to do with step/dir but likely required to provide control to the driver.
    Brilliant - thank you. I agree from a newbie veiwpoint the drawings are difficult to interpret if you aren't experienced in that arena. I'm 99% OK now. Still confused on the 24v bit though :-/

    Can't wait until I have to put settings in Mach4 - that should be fun...

    thanks again
    Every time I am wrong - the World makes a little less sense.

  9. #7
    What is an Open Collector interface?

    thanks
    Every time I am wrong - the World makes a little less sense.

  10. #8
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 18 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,344. Received thanks 187 times, giving thanks to others 65 times. Referred 1 members to the community.
    I was about to apologise having re-read my earlier answer - I'm terrible at writing at one level without trying to understand the level of the reader. My last reply was mostly gibberish - and that's my fault. By all means challenge any reply I offer.

    However, I the Open Collector is I think a new question.

    It's derived from a concept of the use of BJT (don't worry) transistors to switch a device on or off. The BJT has three pins, one of which is the collector. Open Collector, refers to the collector of the BJT not being connected to anything (open circuit). That's from the context of the switch, but of course you use the switch to switch a load (device) on or off. The BJT connects the load to the supply line. There's two flavours of BJTs - NPN and PNP. For an NPN Open Collector system, the collector switches to ground. So, you connect your device to the +V supply, and to the open collector switch. The BJT switches on to connect the collector to ground, which then provides power to the load. PNPs are opposite - the collector switches to +V. So you connect your device/load between the Open Collector output and ground. When the BJT is on the Collector is connected to +V.

    And I re-read that and it still sounds nonsense.

    EDIT:

    One of the main benefits of Open Collector outputs is that you can wire them in parallel - because they only switch to ground (NPN... see above for PNP) then they can't overload other, parallel connected, Open collector outputs.

    EDIT 2:

    The following link gives some explanation. Not sure the internal of the comparator is useful - ignore that bit. This talks NPN BJTs.

    http://www.learningaboutelectronics....tor-output.php
    Last edited by Doddy; 28-08-2020 at 03:29 PM.

  11. #9
    I only mentioned the open collector because it mentions in on connections page 13 of the panansonic manual. Note 2.

    Is it me or is the Panasonic manual confusing on purpose?

    Sorry for the dumb questions - but I guess you have to start somewhere.
    Every time I am wrong - the World makes a little less sense.

  12. #10
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 18 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,344. Received thanks 187 times, giving thanks to others 65 times. Referred 1 members to the community.
    This image refers..

    Click image for larger version. 

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    This is an example of two open-collector drives from the "Deviation counter clear input" and "Command pulse inhibit input". This is just an example intended by the author to show how to switch the input. The real needed behaviour is shown inside the servo controller - there are two corresponding opto-isolators, each with a 4.7k resistor for current limiting. The anode (+) of each LED inside each opto is connected through the resistor to the 12-24V supply, and the cathode (-) is switched to ground by the input circuit - depicted as an open-collector driven system. That works, and should work well. If the driving BJT is ON, the open-collector output is drawn to ground, which allows the LED in the opto isolator to switch the internal gubbins. If the driving BJT is OFF, there is no current path for the opto-isolator LED, and the switches off the internal gubbins.

    You are not required to drive using an open-collector output, but you are required to provide a current path to ground (or something substantially lower than the COM+ pin), you could use a push-button connected from the input to ground perfectly well.

    More likely, you'll be using the MB3

    Click image for larger version. 

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    "Sink" refers to the ability to allow current to "sink" to ground. If you see the term "source" - it refers to the ability to source current from the +V supply.

    Click image for larger version. 

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    This shows that the MB3 has a number of open-collector outputs available to you.


    "Is it me or is the Panasonic manual confusing on purpose?"

    I was about 6 year old when my old man got me interested in Electronics. I'm now 51. I still have to read and re-read manuals like this.

    The problem is that the manual is trying to convey a lot of basic information in as concise way as possible. They're not going to hold your hand to explain things - you're playing in the professional world where you're expected to know what you're doing. Not all of us do. Ask questions.

    and, trite, but :

    The dumbest questions are the ones that you don't ask.

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