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accelerate/deccelerat the analog output value

Created by: corkscrew2 at: 9/6/2014 6:47 AM (2 Replies)

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9/6/2014 6:47 AM	Rate (0)
corkscrew2 Experienced Member Joined: 12/22/2012 Last visit: 12/28/2024 Posts: 91 Rating: (4)	Hii I need to control an ordinary drive connected to the cpu with two digital out (enable, run) and analog out for speed ref. But our application is very sensitive to the ramps of the speed. I want to adjust the drives acc/decc ramps very fast/small to shift the ramping ability of speed to the CPU. Therefore I can modify ramping parameter with by calculation or via a HMI. Maybe we can use PID or with a logic to add/subruct a small but adjustable value from a register which used for the source of analog output. My question is: is there any simple way different? Also can we create an axis for ordinary drives except step motor or servo? I am planning to use 1200. Do you advice others instead of 1200? regards?
	Last edited by: corkscrew2 at: 9/6/2014 6:49 AM
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9/6/2014 4:41 PM	Rate (0)
William_B Posts: 5225 Rating: (1198)	corkscrew2 Hii I need to control an ordinary drive connected to the cpu with two digital out (enable, run) and analog out for speed ref. But our application is very sensitive to the ramps of the speed. I want to adjust the drives acc/decc ramps very fast/small to shift the ramping ability of speed to the CPU. Therefore I can modify ramping parameter with by calculation or via a HMI. Maybe we can use PID or with a logic to add/subruct a small but adjustable value from a register which used for the source of analog output. My question is: is there any simple way different? Also can we create an axis for ordinary drives except step motor or servo? I am planning to use 1200. Do you advice others instead of 1200? regards? Hi there. This question would have done better in the Step7 (TIA Portal) group. Recently there was a simular question. It would suit you well to explore the threads. RAMP FUNCTION FOR S7-1200 Another recent question can be read [LINK 1] that speaks of an FAQ [LINK 2]. I have not looked at the coding, but it should help. MOTION CONTROL WITHOUT PULSES The S7-1200 only has a standard motion control function that use a frequency controlled pulse output. Other variations (example: analog) is not handled by standard motion control. That does not mean you can not develop your own algorithm. Currently I am controlling a standard 3 phase inductive motor that is driven by a standard 1 phase VSD (inverter). The active project is using a pulsing signal to give the VSD a speed setpoint (note: not position). The pulse can be replaced with an analog. A "home made" encoder is giving feedback to the PLC. The ramp up and ramp down is handled by the VSD. But you could handle the ramping with a speed reference (analog / PWM / PTO). A mathematical and rule based concepts are used and deliver positioning with 2mm accuracy with peak speed of 600mm/s - which suits the application. I have done this on an S7-200 (which later on had a Siemens library for this) and S7-1200 PLCs. More than this I am not saying - but hopefully it will be enough to motivate those who can handle the maths behind the control. A very good alternative is to use a VSD that has a motion controller built in. These can have a two phase encoder as feedback to provide a good motion control. The ones we use is not from Siemens and thus out of respect I will not give out the brand name. I hope my comments were helpful. Greetings. w
William_B Posts: 5225 Rating: (1198)
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9/6/2014 10:52 PM	Rate (0)
corkscrew2 Experienced Member Joined: 12/22/2012 Last visit: 12/28/2024 Posts: 91 Rating: (4)	Thanks William, your comments are very usefully. I got the point.

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