Control Variable Frequency Drive with Programmable Logic Controller

PLC
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There are five ways to control a Variable Frequency Drive (VFD) with a Programmable Logic Controller (PLC):

Analog Signal Control (0-10V/4-20mA)

  1. PLC outputs analog signal: 0-10V or 4-20mA.
  2. VFD receives signal: Adjusts frequency accordingly.
  3. Common applications: Speed control, ramping, and modulation.

Digital Signal Control (Discrete Inputs)

  1. PLC sends digital signals: Start/Stop, Forward/Reverse, etc.
  2. VFD receives signals: Executes corresponding actions.
  3. Common applications: Simple on/off control, direction control.

PLC VFD
PLC VFD1008×598 41.9 KB

Modbus Communication

  1. PLC and VFD communicate: Via Modbus RTU/TCP protocol.
  2. PLC sends commands: Frequency setpoints, start/stop, monitoring.
  3. VFD responds*: Confirms receipt, executes commands.
  4. Common applications: Advanced control, monitoring, and diagnostics.

BACnet/IP or EtherNet/IP Communication

  1. PLC and VFD communicate: Via BACnet/IP or EtherNet/IP protocol.
  2. PLC sends commands: Frequency setpoints, start/stop, monitoring.
  3. VFD responds: Confirms receipt, executes commands.
  4. Common applications: Building automation, industrial control.

PROFIBUS or DeviceNet Communication

  1. PLC and VFD communicate: Via PROFIBUS or DeviceNet protocol.
  2. PLC sends commands: Frequency setpoints, start/stop, monitoring.
  3. VFD responds: Confirms receipt, executes commands.
  4. Common applications: Industrial automation, process control.

Additional Considerations

  1. Ensure compatibility: Verify PLC and VFD compatibility.
  2. Configure communication: Set up communication protocols.
  3. Program PLC logic: Develop control logic.
  4. Test and commission: Verify proper operation.

Popular PLC and VFD combinations

  1. Allen-Bradley PLC with Rockwell Automation VFD
  2. Siemens PLC with Siemens VFD
  3. Mitsubishi PLC with Mitsubishi VFD
  4. Schneider Electric PLC with Schneider Electric VFD
  5. Omron PLC with Omron VFD