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SIdharth

Controlling 8 Steppers

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Hello everyone,

I am still kind of new to PLC and this is my first time starting a project and having to choose the components. So the project requires around 40 inputs and 50 outputs. 8 of these outputs are for stepper motors. The motors run at the same time. The PLCs I have seen at most can  control 3 steppers. Expansion module for high speed outputs ends up costing much. So what I would like to know is if there is a better way to do this and the most inexpensive way to carry this out.

Thanks for the help in advance.

 

 

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the most inexpensive way is to define things clearly before making choices.

"The motors run at the same time."

how...? all working in lock step? then one stepper driver can be used to drive several motors.

if using them simultaneously but each of them is running independently, then each will need own driver. to control each driver, you need at least two outputs (step and direction).

you can use regular outputs if you don't mind writing some code and operating them at lower speed (a lot lower).

otherwise you will need more high speed I/O. to get number of I/O you need, you may want to look into modular PLCs.

for small steppers you can get driver built into I/O module such as Beckhoff EL7031 or Wago 750-671 etc.

 

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Posted (edited)

11 hours ago, panic mode said:

the most inexpensive way is to define things clearly before making choices.

"The motors run at the same time."

how...? all working in lock step? then one stepper driver can be used to drive several motors.

Thanks for the answer qnd sorry for the lack for information. The motors will be running independently.

11 hours ago, panic mode said:

if using them simultaneously but each of them is running independently, then each will need own driver. to control each driver, you need at least two outputs (step and direction).

you can use regular outputs if you don't mind writing some code and operating them at lower speed (a lot lower).

For regular inputs, is it by switching the output on and off. The motor will run pretty slow, around 200rpm. Will the speed depend on the time the controller takes to cycle though the program?

I will try to look at the I/O modules with built in driver.

 

Edited by SIdharth
typo

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Just some simple math here:

200 RPM = 72,000 Degrees of Travel per minute 

72,000 Degrees at 10 Degrees per Step is 7,200 Steps per Minute

7,200 SPM equates to 120 Steps per Second

Result is 8.333 milliseconds per step

You're going to want a Stepper Driver, doing this with a PLC discrete outputs I would not try.

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just get the proper hardware that can handle what you need. don't corner your self with ill conceived design.

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