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?> How do you tell an S7-1200 you are working with a rotary axis and not a linear axis

Created by: William_B at: 12/5/2012 8:31 AM (7 Replies)

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12/5/2012 8:31 AM	Rate (0)
William_B Posts: 5225 Rating: (1204)	Hi-ya all, From what I can tell, the motion control for the S7-1200 only uses a linear axis model. Is there a way to tell the S7-1200 that it is a rotary axis? I have an indexing table that can turn only forward. The position counter should restart at zero when a rotation has been completed. One method I can think of is doing pasive homing each time the table should pass the home sensor. Any other ideas that will give better results? Thanks & greetings, w
William_B Posts: 5225 Rating: (1204)
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12/5/2012 3:43 PM	Rate (0)
0_Einstein Grandmaster Joined: 7/7/2010 Last visit: 12/31/2025 Posts: 16342 Rating: (2521)	William B. Hi-ya all, From what I can tell, the motion control for the S7-1200 only uses a linear axis model. Is there a way to tell the S7-1200 that it is a rotary axis? I have an indexing table that can turn only forward. The position counter should restart at zero when a rotation has been completed. One method I can think of is doing pasive homing each time the table should pass the home sensor. Any other ideas that will give better results? Thanks & greetings, w Very good questions! I do not know the answer. However, you can do some fast math on the motion data to create rotary data by use periodic rotary position updates based on linear updates, and convert your rotary control signal to linear control signal using the same type of periodic control signal update, converting rotary command to linear command. Since pi is irrational, over time, round-off will cause it to be off, so maybe using lreal will keep error suffiiciently low. If it was a more powerful PLC, it would likely be built-in. Maybe the open source OSCAT library has some useful functions for your situation. Someone here posted the library ready for import, though you might want to use Siemens SCL import tool to help with s7-1200 SCL support since it is different than s7-300, especially in how the interface is handled.
	science guy
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This contribution was helpful to 1 thankful Users William_B

12/6/2012 7:01 AM	Rate (0)
William_B Posts: 5225 Rating: (1204)	Thank you for your answer. The value of Pi does not play that much of a problem. The encoder on the motor has a known count of pulses. The issue is rather in that the encoder counts goes from 0 (degrees) to maximum (360 degrees) only. The position counter is zeroed each time you pass the home position. [example] When moving from 200 degrees to 180 degrees, you can move forward through 0 degrees to 180 or move reverse 20 degrees. This is a rotational axis rather than a linear axis. -- As you said however, the S7-1200 does not make provision for this. w
William_B Posts: 5225 Rating: (1204)
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12/6/2012 6:43 PM	Rate (0)
0_Einstein Grandmaster Joined: 7/7/2010 Last visit: 12/31/2025 Posts: 16342 Rating: (2521)	Maybe if you contact Siemens via Support Requestthey may have a solution for purchase, or possibly your regional Applications Engineer has some tips/tricks.
	science guy
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This contribution was helpful to 1 thankful Users William_B

12/7/2012 8:07 AM	Rate (0)
William_B Posts: 5225 Rating: (1204)	PS: This problem is not an issue for me anymore. The problem is being resolved by utilising a non-Siemens solution. More outputs are used on the S7-1200 to select the position on the servo drive (Delta Electronics, ASDA A2). The program written in the servo drive decides where the motor should go. The downside is that the user can not set parameters (like speed) from the touch panel.
William_B Posts: 5225 Rating: (1204)	Last edited by: William B. at: 12/7/2012 8:08 AM
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12/7/2012 3:49 PM	Rate (0)
0_Einstein Grandmaster Joined: 7/7/2010 Last visit: 12/31/2025 Posts: 16342 Rating: (2521)	William B. PS: This problem is not an issue for me anymore. The problem is being resolved by utilising a non-Siemens solution. More outputs are used on the S7-1200 to select the position on the servo drive (Delta Electronics, ASDA A2). The program written in the servo drive decides where the motor should go. The downside is that the user can not set parameters (like speed) from the touch panel. With the RS232/485 option on CN3, you can use Modbus/RTU (as an example) and read/write values in the drive to update speed and other parameters if a quick glance at the manual is correct.
	science guy
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This contribution was helpful to 1 thankful Users William_B

12/10/2012 2:19 PM	Rate (0)
William_B Posts: 5225 Rating: (1204)	With the RS232/485 option on CN3, you can use Modbus/RTU (as an example) and read/write values in the drive to update speed and other parameters if a quick glance at the manual is correct. [sigh] You know how it is.. you get things to work with what you have on-hand. I do not have a RS484 module for the S7-1200. Good idea for future use though. Thanks.
William_B Posts: 5225 Rating: (1204)
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4/30/2018 9:30 AM	Rate (0)
Jen_Moderator Posts: 8171 Rating: (174)	New question published by yude13 is split to a separate thread with the subject Command for adaptation of Delta driver and s7 1200. Best regards Jen_Moderator
Jen_Moderator Posts: 8171 Rating: (174)
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