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Changing Motor Direction

Created by: 10Buggs at: 4/27/2014 10:16 PM (5 Replies)

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4/27/2014 10:16 PM	Rate (0)
10Buggs Posts: 3 Rating: (0)	Hi all I'm trying to controll a dc motor using the s7_1200 PLC. I set up the motor control using the "PID-Compact" block and the HSC_1. I can give the motor a setpoint in one direction and it works perfectly. When I try and change the direction and make the motor go back the same distance I cant.I can only make it change direction if I either give it a different distance to go or if I make the setpoint 0 before trying to go back (Which is the same, I think). I notice when I make the setpoint 0, the motor goes back twice the distance because the high speed counter has to count down zero and then goes the set distance in the negitive direction. How can I reset the counter without an external switch? Is there any other way of doing this control? Any help will be greatly appriciated!
10Buggs Posts: 3 Rating: (0)
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4/27/2014 10:30 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	Hi. A description of the hardware you are using would be most welcome. A sketch of how the connections are nice will also be nice. The more info we get, the more usefull the forum will be. Hope to hear from you again.
William_B Posts: 5225 Rating: (1195)
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4/28/2014 11:44 AM	Rate (0)
10Buggs Posts: 3 Rating: (0)	Hi, The attachment contains my project folder with the code if you want to look at it as well as a pdf of the hardware setup. Really hope someone can help - Im very new to this Attachment Mech_project.zip (372 Downloads)
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4/28/2014 1:19 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	10Buggs Hi, The attachment contains my project folder with the code if you want to look at it as well as a pdf of the hardware setup. Really hope someone can help - Im very new to this. My Friend, I am sorry to say thatmy help to you is crippled. My software is TIA V11 SP5 - your software is the later version TIA V12. From the detail you sent, I miss a sketch showing how the components are connected. There is also no way of knowing how the "PWM unit" works. I am not too happy about you using the PID instruction to do control. The signal you get out is a fixed frequency of which the pulse width (% on to % off) is controlled. I suggest strongly that you use "motion control" blocks. These blocks create a variable frequency pulse and do make provision for changing direction. (I guess your direction outputs is not even triggered properly now.) You can start by following the clues I have included in the attached JPG. Also find the PDF manual where Siemens document "motion control" for the S7-1200. Consider reading the post for some further clues: /tf/WW/en/Posts/107231#top Good Luck. w Attachment Create new PTO.jpg (150 Downloads)
William_B Posts: 5225 Rating: (1195)
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4/28/2014 9:05 PM	Rate (0)
10Buggs Posts: 3 Rating: (0)	Hi, Thank you for all the tips and advice. Will read up on the motion control stuff! Will post again if I get it working :)
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4/28/2014 9:49 PM	Rate (0)
William_B Posts: 5225 Rating: (1195)	no worries.. just get that studies done right the first time. w
William_B Posts: 5225 Rating: (1195)
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