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RE: [SherlineCNC] Re: Unwanted Axis Moves Part 2 (Long Post)

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  • Dave Hylands
    What s important as that all of pins 18-25 each have their own wire. They re connected to ground on the Xylotex controller side and on the PC side. If there s
    Message 1 of 23 , Sep 2, 2003
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      What's important as that all of pins 18-25 each have their own wire.
      They're connected to ground on the Xylotex controller side and on the PC
      side.

      If there's only one wire, then it can't let enough current flow through
      for all of the signals, which is why it's important to have one wire per
      pin. You shouldn't need to connect them together.

      What you don't want is a single ground wire which connects to all of the
      ground pins.

      --
      Dave Hylands
      Vancouver, BC, Canada
      http://www.DaveHylands.com/

      > -----Original Message-----
      > From: Randy Gordon-Gilmore [mailto:zephyrus@...]
      > Sent: Tuesday, September 02, 2003 5:31 PM
      > To: SherlineCNC@yahoogroups.com
      > Subject: [SherlineCNC] Re: Unwanted Axis Moves Part 2 (Long Post)
      >
      >
      > At 01:16 PM 9/2/2003 -0000, Bruce wrote:
      >
      > >Which of the pins in the parallel cable are the ground pins and how
      > >would I go about making a shorting bar?
      >
      > Pins 18-25 are ground. I just used a piece of bare solid
      > wire and soldered it across the pins on the back of the
      > socket in my controller box, making sure not to let it touch
      > the metal shell. I don't have the box reassembled yet, so I
      > can't report any results.
      >
      > Best regards,
      >
      > Randy
      >
      > Randy Gordon-Gilmore ,----.___________ ______________
      > _________________
      > ProtoTrains // = = === == || == == == = || ==
      > == == = == =|
      > Rio Vista, CA, USA
      > /-O==O------------o==o------------o==o-----------o==o-'
      > zephyrus@...
      > http://www.prototrains.com
      >
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    • xylotex
      Hi, If you get the three axis kit which includes the IDC26-DB25 cable, you do not need to make a shorting bar. All of the parallel port GND pins on the board
      Message 2 of 23 , Sep 2, 2003
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        Hi,
        If you get the three axis kit which includes the IDC26-DB25 cable,
        you do not need to make a shorting bar. All of the parallel port
        GND pins on the board are connectoed together, and all 25 lines are
        used in the IDC26-DB25 cable, so all you need externally is a good
        sheilded parallel port extension cable that does wire through all 25
        lines.
        As we have seen from previous posts, the system does work with the
        laptop and the problem arises with noise from the Desktop PC. All
        though the STEP & DIR lines are pulled HIGH with a 10K resistor so
        they will not float when no device is attached, they have no other
        active or passive filtering built on to the board. Since we know the
        system works well with the laptop, the real issue becomes reducing
        the noise from the desktop system, not masking it with filters.
        It is not the case that any spike on the STEP lines will cause a
        step to be initiated. The datasheet for the chip specifies that the
        STEP line be HIGH for at least 1 uS to be valid. I have contacted
        the semiconductor manufacturer to find out if noise with time
        durations less than this are excluded from causing steps to be
        triggered, but as of yet, no reply.
        As mentioned earlier, only one end of the sheild around the
        stepper motors wires should actually be earth grounded. Some people
        prefer having this attached at the controller case. I prefer this to
        be attached at the motor end so absorbed noise will go to the CNC
        machine frame (which should be earth grounded) instead of bringing
        over to where noise sensitive devices are located (in the case).
        Just out of curiosity (you don't want to run it this way though),
        have you tried running the desktop without an earth gnd connection?
        Is it possible to bring the PC and your box close enough so that
        the IDC26-DB25 cable, when sticking out of the box (not attached like
        normal) can reach the desktop parallel port without an extension
        cable?

        Jeff
        http://www.xylotex.com
      • Bryan Mumford
        ... I was not referring to the Xylotex board. By hardware triggered step lines I meant typical logic gates. I know the Xylotex board uses an engineered
        Message 3 of 23 , Sep 2, 2003
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          At 1:21 AM +0000 09-03-03, xylotex wrote:
          > It is not the case that any spike on the STEP lines will cause a
          >step to be initiated. The datasheet for the chip specifies that the
          >STEP line be HIGH for at least 1 uS to be valid.

          I was not referring to the Xylotex board. By "hardware triggered step
          lines" I meant typical logic gates. I know the Xylotex board uses an
          engineered driver chip with higher level features.

          --

          Bryan Mumford
          Santa Barbara, California
          http://www.bmumford.com
        • xylotex
          Hi Brian, Cool! I just wanted to make sure that the other 353 members of the group understood this, as the thread concerned a Xylotex product. Thanks, Jeff
          Message 4 of 23 , Sep 2, 2003
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            Hi Brian,
            Cool! I just wanted to make sure that the other 353 members of
            the group understood this, as the thread concerned a Xylotex product.

            Thanks,

            Jeff

            --- In SherlineCNC@yahoogroups.com, Bryan Mumford <bryan@b...> wrote:
            > At 1:21 AM +0000 09-03-03, xylotex wrote:
            > > It is not the case that any spike on the STEP lines will cause
            a
            > >step to be initiated. The datasheet for the chip specifies that
            the
            > >STEP line be HIGH for at least 1 uS to be valid.
            >
            > I was not referring to the Xylotex board. By "hardware triggered
            step
            > lines" I meant typical logic gates. I know the Xylotex board uses
            an
            > engineered driver chip with higher level features.
            >
            > --
            >
            > Bryan Mumford
            > Santa Barbara, California
            > http://www.bmumford.com
          • Randy Gordon-Gilmore
            ... I should point out that I m not using a Xylotex controller. I m using three individual axis drivers. In the Xylotex, all the ground pins are taken care
            Message 5 of 23 , Sep 2, 2003
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              At 05:30 PM 9/2/2003 -0700, I wrote:

              >Pins 18-25 are ground. I just used a piece of bare solid wire and soldered
              >it across the pins on the back of the socket in my controller box, making
              >sure not to let it touch the metal shell. I don't have the box reassembled
              >yet, so I can't report any results.

              I should point out that I'm not using a Xylotex controller. I'm using
              three individual axis drivers. In the Xylotex, all the ground pins are
              taken care of already.

              Best regards,

              Randy

              Randy Gordon-Gilmore ,----.___________ ______________ _________________
              ProtoTrains // = = === == || == == == = || == == == = == =|
              Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
              zephyrus@... http://www.prototrains.com
            • Randy Gordon-Gilmore
              ... I have a good parallel cable with all 25 lines connected, but am using three individual General Controls drivers (one per axis). In the box I was just
              Message 6 of 23 , Sep 2, 2003
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                At 06:02 PM 9/2/2003 -0700, Dave wrote:

                >What you don't want is a single ground wire which connects to all of the
                >ground pins.

                I have a good parallel cable with all 25 lines connected, but am using
                three individual General Controls drivers (one per axis). In the box I was
                just using one line for ground for each driver, but I've just added the
                busbar to tie all the ground pins together at the driver end. Otherwise
                the other 5 ground lines in the cable are not being used.

                Best regards,

                Randy

                Randy Gordon-Gilmore ,----.___________ ______________ _________________
                ProtoTrains // = = === == || == == == = || == == == = == =|
                Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
                zephyrus@... http://www.prototrains.com
              • Alan Marconett KM6VV
                Hi Bryan, Thanks for the rundown. Ingenious to be sampling the inputs in the PICs. Are you also using opto-isolators? And then I assume you use state
                Message 7 of 23 , Sep 4, 2003
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                  Hi Bryan,

                  Thanks for the rundown. Ingenious to be sampling the inputs in the
                  PICs. Are you also using opto-isolators? And then I assume you use
                  state machine code to generate the 4 phases, and also accommodate limit
                  switches? How about an E-STOP switch?

                  Alan KM6VV

                  Bryan Mumford wrote:
                  >
                  > Each axis of the Sherline driver board is controlled by a separate
                  > processor (four processors per board). I used four rather than one
                  > because we didn't know how fast we might want to take the step rate.
                  > Each processor is dedicated to responding to only one step line and
                  > driving only one motor chip. Digital filtering is accomplished by
                  > requiring the step command to be active for more than one query.
                  > Hardware triggered step lines will trigger on any spurious spike as
                  > short as few hundred nanoseconds. I use a Schmitt trigger input, but
                  > I require that the signal be active on more than one inquiry. Each
                  > inquiry might take 3 microseconds. A noise spike is not likely to
                  > last this long. The EMC step command is never shorter than 20
                  > microseconds.
                  >
                  > >What do you do for digital filtering? Do you have some sort of
                  > >processor on the Sherline driver? I could see some sampling techniques
                  > >that could be implemented for slower signals into a microprocessor, but
                  > >the step lines are received at quite a high rate. Much too fast for
                  > >digital sampling! If you can digitally process them in a uP, I'm
                  > >impressed! Or are you talking about hardware, like some conditioning
                  > >with a Schmidt (sp) trigger?
                  >
                  > --
                  >
                  > Bryan Mumford
                  > Santa Barbara, California
                  > http://www.bmumford.com
                • Bryan Mumford
                  There are no opto-isolators. The phase data is clocked into the 7044 with serial data and clock lines, as per the spec. Sherline did not want to implement
                  Message 8 of 23 , Sep 4, 2003
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                    There are no opto-isolators. The phase data is clocked into the 7044
                    with serial data and clock lines, as per the spec. Sherline did not
                    want to implement limit switches. There are two headers on the board.
                    One of them will put all controller chips into reset condition, the
                    other is a panic stop and will immediately removed power from the
                    motors regardless of what the step and direction lines are doing.


                    At 10:07 AM -0600 09-04-03, Alan Marconett KM6VV wrote:
                    >Thanks for the rundown. Ingenious to be sampling the inputs in the
                    >PICs. Are you also using opto-isolators? And then I assume you use
                    >state machine code to generate the 4 phases, and also accommodate limit
                    >switches? How about an E-STOP switch?

                    --

                    Bryan Mumford
                    Santa Barbara, California
                    http://www.bmumford.com
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