SHIV121

MITSUBISHI DDRVI INSTRUCTION

15 posts in this topic

As per attached file im moving 32768 value in D280. when im giving forward command i.e M661 bit on then my servo started to move and its stop when it covered distance as per my value in D280. My problem is that when servo is in moving condition and it covered half of its distance, and at that time when power is gone and comes. Then my servo again started to cover distance from zero, it forget about initial distance it has covered. Is that any way to make pulses in a servo retentive or when power comes then servo travels only remaining distance it has. I DONT KNOW THIS IS STUPID QUESTION OR NOT but please help me if anyone known about this.

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I've not actually used this instruction, but it would appear to be an incremental postioning command, there is another which is an absolute position command which I think would be better suited. When the power is cycled, at the moment the DDRVI instruction tells the drive to increment the value again so when the drive has incremented say 50% of the distance when the power is cycled, then its going to increment the full commanded distance from where it left off. With the absolute instruction DDRVA it will increment to an absolute position (Ie your final destination). Steve

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what is the application exactly? as per my experience in servo programming during power interruption or stop of operation via emergency stop,,,i always provide a homing program ..the the DDRVI command is incremental and once the trigger is activated it will always give the exact number of pulse regardless the servo position. . . ..

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Hii.... Thanx for reply . It is the bolt tightening machine. when it tighted the one bolt then after that servo moves forward for tightening the next bolt. There is an fixed distance between the two bolts. My problem is that when servo is in moving condition and it is in mid position between the two bolts and power gone. After that when power comes the position of servo gets totally disturbed because servo forgets the 50% distance it has traveled. . Is there any solution for this.

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i think you should try the DDRVA command....as what nephets said

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Thank you for reply..... i will try that command. . Please can you tell me what is the difference between DDRVI and DDRVA command. ?

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DDRVI - Incremental. The axis moves the commanded number of pulses from it's current position. DDRVA - Absolute. The axis moves to the commanded pulse number, using the axis current position (D8340) as the reference. Note that the current position resets to zero when you lose power. You will have to use a homing function to reteach the axis where it is. Look at the ZRN and DSZR functions for this. Since you'll have to home after a power cycle anyway, there's not really any need to use the DDRVA instruction. I would probably recommend use go ahead and use it though, as it's useful if the motion is interrupted for other reasons (emergency stop, drive fault, etc.).

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can i use servos encoder feedback given to the high speed counter, and some calculations to make servo travel remaining distance it has when power is come.

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Depends. Is the servo encoder absolute? If so, and if it's a Mitsubishi servo, then you should be able to use the ABS instruction to poll the servo for current position on startup. If it's another brand, you might be able to use a fieldbus to do the same thing.

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.Yes it is an mitsubishi servo. The servo model no. is MR-E-70A-KH003. It has an incremental encoder.

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The MR-E should work with the ABS command, but if it is an incremental servo, then its position will also reset when power is lost.

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If positioning on power up is important to you perhaps you should look at an absolute encoder (if possible on you application). Otherwise can you not just not datum the axis first (as JRoss said). Your PLC can remember the position it should be going to next and just carry on the sequence after the datum. Regards

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hi every body ... i just ask about something in internal servo amplifier controlling ! how to get one pulse signal from mr-j4 after motor have been stopped ? thank you all

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You would get a better response if you start a new thread rather than hijacking this one. Make sure to include the PLC that you are using and motion card of any, as that makes a difference.
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hey hi everyone....thanx all for your support. I want to ask one question. How i connect encoder at plc input. If it is possible by using high speed counter then how i use it. Can anyone explain me about that.

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