RS485 spindles

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RS485 is a serial communication protocol that is used in many industrial applications. It is a differential protocol, which means that it is less susceptible to noise than single-ended protocols like TTL or RS232.

The FluidBoard has a built-in RS485 transceiver. This means that you can connect the RS485 directly to the board.

VFD's commonly feature an RS485 connector. We recommend using RS485, because of the safety polling feature. This means that the machine will go to "ALARM" if the communication to the spindle is lost, or if the spindle speed is not within the expected range.

If your VFD is not supported by this method, you can use the 10v spindle analog output.

Setting up the VFD

Before setting up RS485 communication, you need to configure the VFD and check if your VFD is supported. This is very device specific, so see the manual of your VFD for details.

If your VFD is supported, check the following:

• The VFD should be set to RS485 communication
• Set the baud rate to a reasonable value like 19200 baud, 8 data bits, 1 stop bit, even or odd parity. (19200 8E1)
• Set the modbus address. This should be unique for every VFD connected to the controller.
• Make sure that the parameters for max spindle speed/frequency, min and max frequency and acceleration/deceleration are sane.
• If you have a brake resistor circuit, make sure that the VFD is configured to use it.

While other values should work fine, we recommend using 19200 baud, 8 data bits, 1 stop bit and even parity.

Spindles are dangerous tools! Always ensure spindles are properly clamped before even attempting to run them. Never run an ATC spindle without a tool. This can damage the seals of the spindle beyond repair.

Noise filters and grounding

VFD's generate a lot of noise. It is highly recommended to use a proper EMI filter on your power supply.

We strongly recommend earth grounding your VFD to limit the possibility of electric shock.

Wiring

RS485 devices are susceptible to EMI noise. Always use CAT-6 cable for wiring, prefer a shielded FTP cable over an UTP cable. Keep your cable as far away from any high voltage cable as possible, especially from the VFD spindle and mains cables.

• Connect the shield on one side to the chassis (which should go to the earth of the wall socket).
• Use one twisted pair for the RS485 communication (A+/B- or RS485+/RS485-). All the other pairs should be connected to the GND. Note that GND is not the shield!
• Connect the A+ and B- pins to the RS485 A+ and B- pins on the VFD. Connect the GND on the VFD.
• There is no need to connect GND on the controller.

The A+/B- text on the FluidBoard v2.04 is incorrect. Connect A+ to B- and visa verse.

Configuration

uart1:
  txd_pin: gpio.1
  rxd_pin: gpio.6
  baud: 19200
  mode: 8E1

Huanyang:
  uart_num: 1
  modbus_id: 1
  tool_num: 0
  speed_map: 0=0% 0=25% 6000=25% 24000=100%
  off_on_alarm: false

For more details, see the FluidNC Wiki on spindles.