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    Default Step2Linear

    My Step2Linear boards are on the way. I am going to be converting a knee mill that had a Mitutoyo Millstar III control on it. The control consisted of Glentek 7115 Servo Amplifiers and Glentek DC brush Servo motors.

    I have a couple questions. The Step2Linear manual seems to indicate a diagram to make up the serial cable to communicate with the board yet unless I missed it, I couldn't find it.

    Secondly, the manual indicates using a center tapped 20V transformer for the power supply, after rectification does that not yield about 28VDC? Which is way over the 18VDC limit. Now if I got a 12VAC center tapped transformer, that should yield me 16.9V correct?

    I'm sure I will have some basic questions, I will ask here for everyone's benefit.
    Marty

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    Default Re: Step2Linear

    Because I have space considerations, can Step2Linear be mounted vertically to a piece of aluminum and one Step2Linear on EACH side of the mounting plate? Are there heat issues to contend with?
    Marty



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    Default Re: Step2Linear

    The power supply needs plus and minus 14 volts so the 20 volt ac yields 28 volts DC with a centertap, which is +14 and -14.
    I say a 20 volt transformer because it will usually be about 22-23 volts AC unloaded which will still be below the absolute max which is 36 volts DC.

    The boards don't produce any heat, so you can mount them anyway.

    Also i include a programming cable with the order so you don't have to make one.

    Larry

    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com


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    Default Re: Step2Linear

    Quote Originally Posted by Larken View Post
    The power supply needs plus and minus 14 volts so the 20 volt ac yields 28 volts DC with a centertap, which is +14 and -14.
    I say a 20 volt transformer because it will usually be about 22-23 volts AC unloaded which will still be below the absolute max which is 36 volts DC.

    The boards don't produce any heat, so you can mount them anyway.

    Also i include a programming cable with the order so you don't have to make one.

    Larry
    Ah! Didn't equate Larry, HALF the 20V! Doh!
    I salvaged a +/-15VDC power supply from another control I plan to use, so I should be good there.
    Thanks for the cable, much appreciated.

    Gathering parts now. Will take pics and keep everyone posted. I do have a few questions about connections to the Glentek servo amps. I'll post them here later on.

    Thanks Larry, for putting these together and supporting them. Here is a link to pictures of the mill:
    https://plus.google.com/u/0/photos/1...52313798869265



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    Default Re: Step2Linear

    Ok, my machine has Glentek SMA7115 Servo amplifiers with a DC Buss voltage of 170V. I am in the planning stages. I have created a table that connects the SMA7115 to Step2Linear with a few questions at the end of the table:

    Terminal/Signal Name Description Step2Linear Termial
    J1-1 DIFF SIGNAL IN (+) Differential signal input Step2Linear + Ref output
    J1-2 DIFF SIGNAL RET (-) Differential signal return Step2Linear -Ref output
    J1-3 SIG IN(+) Single ended signal input
    J1-4 COMMON Common for all signals & shields Step2Linear Common
    J1-5 TACH IN Tachometer input. (not used in current mode)
    J1-6 MTR CUR Scale factor: 1V=5A Step2Linear Current Input
    J1-7 LIMIT + Inhibits motor in + direction
    J1-8 LIMIT - Inhibits motor in - direction
    J1-9 INHIBIT Inhibits motor in both directions Step2Linear Enable Output (via relay contact)
    J1-10 FAULT Goes low if there is a fault in the amplifier. May be externally forced low to stop motor rotation
    J1-11 COMMON Comon for all signals and shields Step2Linear Common
    J1-12 RESET Resets the fault latch. May also be used as an inhibit input
    J1-13 LS/ECB Goes high if the Low Speed Electronic Circuit Breaker turns on
    J1-14 HS/ECB Goes high if the High Speed Electronic Circuit Breaker turns on
    J1-15 OVERVOLT Goes high if the buss voltage rises above 250VDC
    J1-16 OVERTEMP Goes high if the temperature of the amplifier rises above the specified temp.


    A few questions:
    Servo Power Supply=170VDC. What is the value for the voltage divider resistors for the +/- Low Voltage input for Step2Linear?
    Is the current monitor output from the SMA7115 servo amplifier, pin J1-6 adequate and typical for the Step2Linear Current Input?
    Would it be suggested to use the Servo Amplifer Inhibit to hold it low until the computer/control software is on line?
    Should the limit switch inputs be fed to the computer/control inputs as well as the servo amplifier?



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    Default Re: Step2Linear

    A few questions:

    Servo Power Supply=170VDC. What is the value for the voltage divider resistors for the +/- Low Voltage input for Step2Linear?

    I would use a 15K, 5 watt and a 1.5K 1 watt in series. Take the signal off the 1.5K

    Is the current monitor output from the SMA7115 servo amplifier, pin J1-6 adequate and typical for the Step2Linear Current Input?

    probably..you could try it The step2lin only used the current input for display in vipertune at this time.

    Would it be suggested to use the Servo Amplifer Inhibit to hold it low until the computer/control software is on line?
    Yes. you need that

    Should the limit switch inputs be fed to the computer/control inputs as well as the servo amplifier?
    Are you using home switches too ? The limit switches could be all ORed together to click the Estop input on the BOB.

    Larry

    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com


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    Default Re: Step2Linear

    Quote Originally Posted by Larken View Post
    A few questions:

    Servo Power Supply=170VDC. What is the value for the voltage divider resistors for the +/- Low Voltage input for Step2Linear?

    I would use a 15K, 5 watt and a 1.5K 1 watt in series. Take the signal off the 1.5K

    Is the current monitor output from the SMA7115 servo amplifier, pin J1-6 adequate and typical for the Step2Linear Current Input?

    probably..you could try it The step2lin only used the current input for display in vipertune at this time.

    Would it be suggested to use the Servo Amplifer Inhibit to hold it low until the computer/control software is on line?
    Yes. you need that

    Should the limit switch inputs be fed to the computer/control inputs as well as the servo amplifier?
    Are you using home switches too ? The limit switches could be all ORed together to click the Estop input on the BOB.


    Larry
    So in your "Connecting to the Analog Servo Amplifier" diagram in the Step2Linear manual, on the voltage divider, R1 would be the 1.5K and R2 would be the 15K?

    I am going to let the control take care of the limit switch inputs. Nothing to the servo amps. if there is a limit fault the controller will disable the amplifiers.

    Now that said, the controller has an "Enable All" circuit which does not go low until the computer is on line, the controller is put on line. You have an enable circuit as well. Since everything powers up, at the same time, Step2Linear will be powered up long before the controller comes up, and the amps will not be enabled until the Control is put on line. So, that said, I would imagine I could ignore the Enable Out on Step2Linear? It may have been good for you to have an optional Enable input from the controller, then each amp could have been controlled from Step2Linear. Thoughts on this?



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    Default Re: Step2Linear

    Larry,
    Step2Linear has a fault output
    Servo Amps have a fault output

    It does not appear that Step2Linear monitors the Servo Amp Fault output. SO, should my control only monitor the Fault output of Step2Linear?
    Again, it might have been nice to have a Servo Fault Input from Step2Linear

    Marty



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    Default Re: Step2Linear

    wow, its getting complex, with every module having enables and faults !

    So in your "Connecting to the Analog Servo Amplifier" diagram in the Step2Linear manual, on the voltage divider, R1 would be the 1.5K and R2 would be the 15K?
    No, R1 would be the 15K going to the High voltage and R2 would be the 1.5K going to ground

    I am going to let the control take care of the limit switch inputs. Nothing to the servo amps. if there is a limit fault the controller will disable the amplifiers.
    They will respond faster if you leave them directly on the servo amps. It will also be better to protect your machine and motors. If the S/W is not responding then the amps may crash hard.

    Now that said, the controller has an "Enable All" circuit which does not go low until the computer is on line, the controller is put on line. You have an enable circuit as well. Since everything powers up, at the same time, Step2Linear will be powered up long before the controller comes up, and the amps will not be enabled until the Control is put on line. So, that said, I would imagine I could ignore the Enable Out on Step2Linear?
    BTW, Are you running Mach3 or Flashcut ?
    Use the enable out on the Step2lin and the controller ANDED together. See in my diagram the Inhibit relay coil goes to the +16 volt . Have the Controller supply the 16 volts instead when it is enabled. That way the coil needs both signals to enable the drive. You can use a PNP transistor, or a small relay to do this.

    Step2Linear has a fault output
    Servo Amps have a fault output

    It does not appear that Step2Linear monitors the Servo Amp Fault output. SO, should my control only monitor the Fault output of Step2Linear?
    It may have been good for you to have an optional Enable input from the controller, then each amp could have been controlled from Step2Linear. Thoughts on this?
    The Low voltage input can act as a fault input. If you really wanted to, you could have a small relay shorting out that 1.5K resistor when the drive faults to make the step2lin reset. But you don't need to.
    Just have the drives Fault output go back to the controls Estop input too, just as you will have the Step2lin's Fault output go back to the controls Estop input.


    Larry

    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com


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    Default Re: Step2Linear

    Larry,
    Is there any reason why the Enable output from Step2Linear can not go directly to the Glentek 7115's Inhibit input? You mention anding the control output and the Step2Linear output, through a relay or a transistor?
    The idea I suppose is that both must be online before enabling the servo amplifier. You show a relay in your wiring example in the instructions.



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    Default Re: Step2Linear

    What you want is for the Amp to be disabled until the Step2lin enables it.
    This is because when power is applied to the Step2lin, the analog outputs jump around for a split second as the step2lin cpu is initializing the D-A converter. After the analog is stable the step2lin then brings the enable low.

    Thats why i use a relay contact that is normally closed when there is no power to it.
    If the Enable input on the amp is Disabled when pulled high through a resistor, that would work. But you could'nt use the step2lin PowerSupply to pull it high.

    Larry

    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com


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    Default Re: Step2Linear

    Quote Originally Posted by Larken View Post
    What you want is for the Amp to be disabled until the Step2lin enables it.
    This is because when power is applied to the Step2lin, the analog outputs jump around for a split second as the step2lin cpu is initializing the D-A converter. After the analog is stable the step2lin then brings the enable low.

    Thats why i use a relay contact that is normally closed when there is no power to it.
    If the Enable input on the amp is Disabled when pulled high through a resistor, that would work. But you could'nt use the step2lin PowerSupply to pull it high.

    Larry
    Hi Larry,
    Understood. However why the need for the relay. My Glentek servo amp has a logic level of 5V, when sunk to the common pin of the amplifier would enable it. Can I avoid using the relay?
    I sent you the docs on the Glentek Servo amp sometime ago.

    Thanks Larry.
    Marty



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