PLZ Suggest a PLC for three yaskawa 750W servo drives

[codemax 0]

Dear Friends, I have three 750W servo drive ( SGDS-08A12A ) and motors (SGMAH). I need an plc which can be used to control all three sets. All i need to do is turn these motors half turn CW and half turn CCW in my whole process in a syncronised way. Any help will be really appreciated . Best Regards Max

[JordanCClark 0]

Yaskawa makes a PLC that will connect over Mechatrollink to their servos. Yaskawa PLC info I've only had limited and painful success using yaskawa in other platforms. No real experience in using these PLC's-- I just have a couple that are on OEM equipment.

[Michael Walsh 268]

If the servos are analog servo drives and can accept a pulse train input command and you have 3 axes doing simple positioning moves, then a CP1H would work well. It would be quite simple. I would recommend getting a cable from the drive that connects to a terminal block to make the wiring a bit easier and would recommend using the function blocks in CX-Programmer to command the movements.

[codemax 0]

Thanks Jordan, but yasakwa mechatrolink is for a vast connectivity and will be expensive for the kind of low end project i am involved with. Dear Omoron expert, Thanks for your suggestion, I am using SGDS-08A12A ServoPacks ( three ) to drive 3 Servo 800w. I believe they take pulse inputs. But my issue with CP1H which i cannot find even after lots of googling is , that e.g : My objective : 3 Motors will be on a flat table ( fixed ) and the motor one and third are to be moved 100mm CW and 20 mm CCW, and second motor, the one in between the two sync motioned motors have to do only a CW motion. Now, this 2nd motor is doing a CW motion suppose at 100 RPM, then the motor 1 and 2 should do the 100MM forward at the same RPM, so basically in CW motion all 3 motors will be on same RPM. NOw, to achive this i think i have to use the encoder pulses to be read by the PLC to manupulate the values in the logic. I am not sure what connectivity will it require to send motors`s encoders value to the PLC input to vary a PLC logic output to drive motor accordingly. Since you are OMORON expert, I am sure the solution is very near to be achieved. Also i am thankful to you both for taking out your time and replying, ill really appreciate your continuos assistance and will be thankful for the same. Regards Max

[Michael Walsh 268]

If you are referring to interpolation with the two (synchronous) axes, the CP1H is not a good choice for that type of application. You are better off using a CJ2M processor with a CJ1W-NC4_3 pulse train control module. If you do use the CP1H, you do not need to bring the encoders back to the PLC, you just send pulses out and watch for the error signal and position completed signal. From the PLC's perspective, it is an open loop system. The position loop is closed in the servo drive.

[codemax 0]

Dear michael, Hope you are doing great, I would like to tnank you for the answer, but I have Google the word interpolation regarding servo motor, but I cudnt find any good article. In short I domt kmow what is interpolation andwhere is it required inmy project, also why can't cp1h achieve it . Regards Max

[Michael Walsh 268]

I will try to explain linear interpolation: In this example, 2 servo axes are acting as an X and a Y axis in a system. In the first example move, the axes are at (0,0) on the X,Y scale. The desired position after the move is (600,300). If both axes are commanded at the same speed, then after both axes have travelled 300 units, the Y axis stops moving as it has reached its desired position. The X-Axis would then continue on until it reaches 600. The drawing below attempts to show what this might look like: Now, making the same move using linear interpolation: The axes will be commanded in such a fashion so that both axes arrive at their desired position at the same time. See the picture below: Of course, the X axis will be moving twice as fast as the Y axis in this example to move 600 units in the same time that the Y is moving 300. The CP1H, CP1L and CP1E PLCs cannot do this because this is a more advanced calculation that was not built into the CP1 family. It is meant for simple commands. Of course it would be possible to calculate the proper speed for each axis and issue a command at the same time (ladder wise), but the result in a CP1 PLC would not be true interpolation.

[codemax 0]

Dear Michael Walsh Thank you for the explanation, I do understand interpolation calculated by the CP1H vs the CJ PLC. But i do not understand why do i need interpolation in the project ? Michael, your assitance is very important as i dont want to end up with a wrong product. :) Regards Max

[Michael Walsh 268]

Max, You may not need interpolation for your project. I did not understand for sure what you meant by "synch motioned motors". I wanted to make sure that you did not mean interpolation. It is very possible (probable based on your response) that you do not need interpolation. If you do not need to do linear interpolation, then the CP1H will work well for your application. Good luck!

[codemax 0]

Dear Michael, Hope you are doing great ! I just took some time to respond, as i was trying to make a animation on what actually i want to achive. Please see the image and animation attached. Please rensond me if i am on the correct path ? i really appreciate your time and efforts. ANIMATION : Paper is moved/gripped by S1 and S2 with the help of rubber roller R1 and R2. RED marks in the roller indicates the home position of the servo. Regards Max Edited 12 Jun 2013 by codemax

[Michael Walsh 268]

Does the second servo drive move both wheels (S2 and Z1)? Does S1 and S3 need to be exactly in synch with S2? If it needs to be exactly in synch, then the CP1H is not the proper PLC. I would lean more towards the NJ3 with EtherCAT servos for your application. It is more expensive, but provides the very tight synchronization that you would need. If S1 and S3 just need to be approximately in synch with S2, then you might be able to use the CP1H. You would be able to issue commands at nearly the same moment, but the servos would not really be synchronized. The NJ3 would also be easier to program for this type of application than the CP1H.

[codemax 0]

Dear Walsh, So glad to see your reply. Hope you are doing great !. Does the second servo drive move both wheels (S2 and Z1)? > YES, the both cylinders are geared. Does S1 and S3 need to be exactly in synch with S2? >> YES or the paper will warp and torn when the stamp grips on the paper and speed in not in sync. I understand that for my application a PLC is not enough and a motion controller is needed. Will the omron yaskawa MP2300 is good enough ? will i be able to connect 3 servos in mechatrolink connection to achive that motion shown in the ANIMATION ? Thanks again for your time Michael. Thanks a lot. wish to hear back soon. Take care Regards Max

[Michael Walsh 268]

I am sure that the MP2300 could handle this, but I do not know much about that controller, so please get a second opinion. Good luck!

[codemax 0]

Thanks a lot Michael, really appreciate ! Regards