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M90 analog out to inverter drive


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Hi guys,


I have a retrofit project for a small packaging machine using a M90-TA2-CAN.

Among others, i want to control the speed of a 3-phase motor using a 0-10VDC analog output.

The machine is already equipped with a Frequency inverter drive and the speed is adjusted by a 1K potentiometer.

Now the customer prefers to adjust the speed via HMI...

The drive has a +10V and ground source which passes though the pot and the wiper result is connected to speed reference terminal.

There is no terminal for my 0V PLC analog output and therefore i can't use the analog output of my M90.

Any ideas how to solve this problem?


Thanks in advance,


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  • MVP 2014

The 0V of the PLC analogue out is the 0V supply terminal - the analogue out is not galvanically isolated.


You may be able to get it working, but there are possible signal isolation issues.


Do you know if the ground (0V) of the 10V signal is isolated from 0V (ground) of the drive auxiliary supply? 


Are you using the same 24V supply for the PLC that is used for the auxiliary functions on the inverter drive?

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Dear Simon,


Thanks for your reply.

Yes I tried to run the PLC with 24VDC supply from the inverter's terminal card but it does not work.

I connected 0V of the PLC analog out to inverter's analog ground.

Before connecting the +- 10v analog output to inverter's input, i measure with multimeter and everything is ok.

When i connect  +- 10v analog output to inverter's input, i get a very high dc value and inverter does not work.

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I tried everything but i didn't manage to get it work!

I also connected the +10v of the card directly to speed reference signal.

Normally this should force the drive to run the motor continously at 50Hz...

But it doesn't work again!

The drive is made by an unknown chinese manufacturer and the manual is written only in chinese language.


Since the motor is just 2hp, i already installed a new Lenze drive and it works like a charm!

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