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Calculate speed of a movement

Created by: PaulKeizer at: 11/5/2014 10:35 AM (4 Replies)

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11/5/2014 10:35 AM	Rate (0)
PaulKeizer Posts: 19 Rating: (1)	Hello, Is there a standard option to calculate speed when programming an ET200S 151-8 CPU? I am doing a movement and I want to know the mm/s. And I can program something to do this, but is it possible with a standard block? Thanks
PaulKeizer Posts: 19 Rating: (1)
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11/5/2014 11:35 AM	Rate (0)
Jens_app Gold Member Joined: 1/5/2011 Last visit: 3/13/2025 Posts: 815 Rating: (123)	PaulKeizer Hello, Is there a standard option to calculate speed when programming an ET200S 151-8 CPU? I am doing a movement and I want to know the mm/s. And I can program something to do this, but is it possible with a standard block? Thanks Dear PaulKeizer, that is a very vague question, please elaborate.... Give us more detail... How is thevelocity measured? What is the measuring principle?Are you using a laser? An encoder? Describe the complete picture a bit, are you using a motor to drive a belt,... Are you going from circular to linear movement? Thanks in advance. Kr, Jens
	Keep it simple and on-topic. A simple straight-to-the-point answer is often of more quality than a complicated one.
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11/5/2014 11:51 AM	Rate (0)
PaulKeizer Posts: 19 Rating: (1)	Sorry, The position is measured with linear position sensor. This sensor is connected 4-20 mA. So I want to know the changing of the value in an amount of time. It is a plate moving with a spindle with thread driven by a hydraulic motor. This is from one of our standard machines. And right now we are adjusting the speed of the hydraulic motor with a flow restrictor just by feeling. But I want to adjust this setting by speed so for every machine we build it will be the same speed.
PaulKeizer Posts: 19 Rating: (1)
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11/5/2014 1:48 PM	Rate (1)
William_B Posts: 5225 Rating: (1204)	PaulKeizer Sorry, The position is measured with linear position sensor. This sensor is connected 4-20 mA. So I want to know the changing of the value in an amount of time. It is a plate moving with a spindle with thread driven by a hydraulic motor. This is from one of our standard machines. And right now we are adjusting the speed of the hydraulic motor with a flow restrictor just by feeling. But I want to adjust this setting by speed so for every machine we build it will be the same speed. Hi. There is no single ready-made function that I know of that will do what you need. You will have to develop your own. There are potentially x2 solutions to get the end result you seek. [a]Calculating velocity Calculate the relative distance travelled every (small) fixed time span. The absolute position read at that moment and the absolute position on the previous reading will be needed. The two readings will be the fixed time span apart from one another. Velocity = (PositionNow - PositionEarier) / TimeSpan A normal PLC timer could be used if the velocity is not that big or an accurate reading is not required. Alternatively a Timed Interrupt should be used to increase accuracy. Still the analog reading may make things difficult in finding an accurate reading. [b]Measure time Because the calculations are needed for system tuning, another possibility is available: measure travel time between two points. For argument sake the plate moves the whole stroke from "4mA" to "20mA". The time can be measured from "6mA" to "18mA" position points. To increase accuracy Timed Interrupt could be used, especially if the PC cycle time is long. The measurement is over a longer distance and will be more accurate for making the required adjustment. ------------ I hope this is helpful. Greetings. w
William_B Posts: 5225 Rating: (1204)
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3/26/2018 8:05 AM	Rate (0)
Jen_Moderator Posts: 8171 Rating: (174)	New question published by MMaarriinn is split to a separate thread with the subject Does anybody know how to create ladder logic which can calculate a speed of a movement?. Best regards Jen_Moderator
Jen_Moderator Posts: 8171 Rating: (174)
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