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Created by: SAR-CNT at: 3/15/2018 11:05 AM (12 Replies)

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3/15/2018 11:05 AM	Rate (1)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hi Help me I use the trajectory of motion PTO MC_MoveAbsolute S7-1200 1215 v4.2.1 TIA v15 up1 there are large errors when moving along the X axis (I look at the graphs) X=218,90 and X=223,37 Y=85,44 and Y=85,78 movements are launched simultaneously and cyclically through the function MC_MoveAbsolute Technology objects: Servo_X and Servo_Y_1: ActualPosition and ActualVelocity (I look at the graphs) Attachment 1122qq.png (270 Downloads)
	Last edited by: SAR-CNT at: 3/15/2018 11:13:47 AM Last edited by: SAR-CNT at: 3/15/2018 12:27:39 PM
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3/15/2018 12:09 PM	Rate (0)
Mister T Silver Expert Joined: 4/28/2015 Last visit: 10/25/2024 Posts: 398 Rating: (57)	Hello, could you please give some details of your problem(s)? And I think you mean TIA Portal V14 SP1 or TIA Portal V15 (without SP1 - or do you still habe one)...?

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3/15/2018 12:24 PM	Rate (0)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hi I test the MC_MoveAbsolute function but on different cycles I get different values for the position... Version V15 Update 1 as can be seen from the graphs in the X axis, there is a difference in position
	Last edited by: SAR-CNT at: 3/15/2018 12:27:13 PM Last edited by: SAR-CNT at: 3/15/2018 12:30:59 PM
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3/15/2018 3:12 PM	Rate (0)
#dP Posts: 2826 Rating: (686)	@Mister T: SAR-CNT is showing a (very good!!) time graph of some measurements of his process. The same graph is repeated 4 times, each containing some measurement that he is putting to our attention. There are two axis: X and Y. Each has measurement for velocity and position. Two measurement margins are placed in position where velocities Vx1 = Vx2 and Vy1 = Vy2. The positions are however different. Please - Do you have any indication on why the position measurements are so very different? @SAR-CNT: I compliment you on the graph and the detail. The picture is a bit big, which makes it at first hard to follow. I have no clue why the velocities would be the same but positions different. I have no faith in the S7-1200 to do a good linked (coordinated) movement. The motion control is regulated on a cycle time of 10ms (old standard). The trigger to start a motion can be incorrect by x2 that amount. Then the values you read for the graph has 3 problems - the scan and update of (1) motion control #1 (2) motion control #2 (3) update rate of the graph. None of these are in synchronize with each other. Regardless of the mentioned, the two sets of velocities are the same - that is strange. BR
#dP Posts: 2826 Rating: (686)
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3/16/2018 10:06 AM	Rate (0)
Mister T Silver Expert Joined: 4/28/2015 Last visit: 10/25/2024 Posts: 398 Rating: (57)	Hello, is it possible, you have a problem with cycle time of OB "Main"? PTO is not working in closed loop control mode and with an axis speed 58,6 mm/s the distance of 5mm means an delay of 85ms... If you do other measurements with the trace functionality of TIA Portal, you do not have to copy all the bitmaps in one, you could use the display below the trace picture, like in my example picture... Attachment TraceExample.png (245 Downloads)

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3/16/2018 11:52 AM	Rate (0)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hi ===== servo_X: Pulser per motor revolutions: 2048 Load movement per motor revolutions: 40.0 mm Maximum velocity: 1200mm/sec servo_Y_1: Pulser per motor revolutions: 1024 Load movement per motor revolutions: 5.0 mm Maximum velocity: 97mm/sec ==== I have problems with positioning on X I'm here and think that 40.0mm is the critical positioning value for this speed ???? by Y I have no problems Attachment 1123qq.png (231 Downloads)
	Last edited by: SAR-CNT at: 3/16/2018 12:36:55 PM Last edited by: SAR-CNT at: 3/16/2018 12:44:59 PM
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3/16/2018 12:45 PM	Rate (0)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hi @Mister T: thanks for the advice.... Attachment 1124qq.png (231 Downloads)
	Last edited by: SAR-CNT at: 3/16/2018 12:47:35 PM Last edited by: SAR-CNT at: 3/16/2018 12:48:00 PM Last edited by: SAR-CNT at: 3/16/2018 12:49:48 PM
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3/16/2018 1:39 PM	Rate (0)
Mister T Silver Expert Joined: 4/28/2015 Last visit: 10/25/2024 Posts: 398 Rating: (57)	Hello, I did some calculations for axis X: Position: 2048 pulses/revolution and 40 mm/revolution = 51,2 pulses/mm Velocity max: 1200 mm/s = 61440 pulses/s = 62kHz Is your motor driver able to handle this pulse frequency? By moving with maximum velocity, you get with every cycle time a variance of: CycleTime = 8ms = 0,008s -> 9,6mm CycleTime = 13ms = 0,013s -> 15,6mm Maybe this could be also a problem. Is it better if you use the motion commands in cyclic interrupt OB with 5ms cycle time...?
	Last edited by: Mister T at: 3/19/2018 1:59:35 PM
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3/16/2018 2:36 PM	Rate (0)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hello I'll try the OB=5ms option

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3/17/2018 11:24 AM	Rate (0)
SAR-CNT Silver Member Joined: 1/23/2013 Last visit: 8/10/2022 Posts: 226 Rating: (5)	Hello, Mister T I have big problems when I moved the X axis control in the OB (5ms) Attachment 1125qq.png (220 Downloads)

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