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-   -   Controlling DC drive with Siemens PLC S7-1500 (http://www.plctalk.net/qanda/showthread.php?t=113709)

samvivi7 January 11th, 2018 10:36 AM

Controlling DC drive with Siemens PLC S7-1500
 
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Hey Guy,

I would like to control the (attached) DC motor drive with my S7-1500 PLC through an HMI.

when i say control i mean only the speed.

any help is appreciated.

Thank you,
Sam

Saffa January 11th, 2018 01:00 PM

This controller appears to be very basic and designed for control using a 10k potentiometer. You would need a motorized potentiometer like high end stereo equipment used once upon a time.

Personally I'd look at finding DC motor controllers that accept a 0-10V or 4-20mA reference signal

samvivi7 January 11th, 2018 01:30 PM

oh ! so not an easy one.
well, i will leave it as is. : (

janner_10 January 11th, 2018 01:46 PM

Depends what the control voltage is returning on S2, if its 0v to 10v then you can simply substitute this with a PLC analogue output.

Measure across S1 and S3 and see if it's 10v.

samvivi7 January 11th, 2018 02:36 PM

Janner10

thanks for the help. So i called the manufacturer and its 5V out and also they want me to use a Analog interface and isolation module.

since i cant spend any money on this (project) i will have to let things be.

thanks for all the help guys,
Sam

damica1 January 11th, 2018 02:58 PM

How many "Relay Outputs" can you dedicate to control the motor speed?

Build a Voltage Dividing Network, Example: put 5 resisters in series (lets say 2k each).
That would only cost a couple of dollars!

Now program the drive to have a min-max speed of let's 30hz - 70hz.

Now wire each PLC relay output in between each resistor, now just program your hmi with a button for 70hz, then one for 60hz then one for 50hz then one for 40hz then one for 30hz, with each turning on the associated relay output.

This would at least allow you to set various motor speeds, changing the resistor network would allow for different speed adjustments.

Just an Idea - this would cost no more than a couple of dollars!!

janner_10 January 12th, 2018 01:32 AM

Quote:

Originally Posted by samvivi7 (Post 764748)
Janner10

thanks for the help. So i called the manufacturer and its 5V out and also they want me to use a Analog interface and isolation module.

since i cant spend any money on this (project) i will have to let things be.

thanks for all the help guys,
Sam

Doesn't really matter what they want, it's not their project.

Just restrict your 0v to 10v output from the PLC to a max of 5v. If your budget is zero, you haven't got many options.


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