11.6.4 Adjustable Frequency Drive with Modbus RTU
The adjustable frequency drive communicates in Modbus RTU format over the built-in RS-485 interface. Modbus RTU provides access to the control word
and bus reference of the adjustable frequency drive.
The control word allows the modbus master to control several important functions of the adjustable frequency drive:
•
Start
•
Stop of the adjustable frequency drive in various ways:
Coast stop
Quick stop
DC Brake stop
Normal (ramp) stop
•
Reset after a fault trip
•
Run at a variety of preset speeds
•
Run in reverse
•
Change the active set-up
•
Control the adjustable frequency drive’s built-in relay
The bus reference is commonly used for speed control. It is also possible to access the parameters, read their values, and where possible, write values
to them. This permits a range of control options, including controlling the setpoint of the adjustable frequency drive when its internal PI controller is used.
11 RS-485 Installation and Set-up
FC 300 Design Guide
11-12
MG.33.BC.22 - VLT
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is a registered Danfoss trademark
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