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08-21-2012 04:57 AM

How is the inverter connecting with PLC?


My company bought a PLC for an extruding machine recently, the machine was controlled by an inverter before, now they need the PLC to control it, no one knows how to connect it, I am also a newbie about the inverter and PLC, hope someone can help me out.

Many thanks.
08-21-2012 05:04 AM
Top #2
08-21-2012 05:04 AM
Generally there are three ways to connect inverter with PLC:
1) PLC digital output terminal connect with inverter digital input terminal, to get multi-step speed & start/stop function through the PLC.
2) PLC analog output terminal connect inverter analog input terminal, it can achieve stepless speed control.
3) PLC control inverter through communication protocol, but it requires they have the same communication structure and protocol.
08-21-2012 05:28 AM
Top #3
08-21-2012 05:28 AM
If you are referring to frequency inverter, then it depends on what kind of interface is available on the inverter itself. It could be an analog input, PWM input or serial RS485 inputs. The T100MD+ PLC is able to interface to any of these interface. The PLC has two channels of 0-10V analog outputs that can connect to the frequency inverter analog input and it is also able to send/receive ASCII or binary data via its RS485 port, which makes it possible to interface to inverter via serial interface easily and accurately.

The PLC has one RS232 port and one RS485 port. You can connect the RS232 to the PC and the RS485 port to the frequency inverter (assuming your inverter has RS485 - please verify with the supplier of the inverter as we are not in a position to advise what's on a third party product).
08-21-2012 05:39 AM
Top #4
08-21-2012 05:39 AM
Usually, in my experience, we use a digital input to start the frequency inverter and one input to reference the analog input. The associated HAND-OFF-AUTO will apply the input to reference the analog input. In hand the only input active will be "RUN" and in auto the inverter will be commanded from the PLC digital output to "RUN" and activate the "SPEED REFERENCE" input which selects the analog input from the PLC.
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