To connect a spindle to the controller, it is important to determine the type of connection needed. In general, all spindles and VFD combinations fall into one of the following categories. Some may be able to be configured to function in multiple ways.

Regardless of connection type, the spindle must be connected safely. Ensure that the connections follow local regulations for safety, this may include a safety relay to cut power to the device in emergency conditions. Be sure that you can turn the device off in an instant, especially during setup.

Most VFDs will have two signals for controlling them:

To control the speed, we use a 0-10V signal. 0V is the lowest RPM, and 10V is the highest RPM. Please note that 0 volts does not always correspond to 0 RPM; this can be configured in our software, as some spindles have a minimum speed.

It's also important to understand that controlling a VFD solely via 0-10V is unsafe, as any signal on these wires could activate the spindle.

However, for switching the drive on and off, there are two types of control of a VFD:

Type 1: Tool On/Direction Type 2: Clockwise (CW, FORWARD) / Counter-clockwise (CCW, REVERSE)

Both types are supported, but please check your manual and/or set up your drive accordingly. We will show how both types can be controlled.

Please note that the direction is determined by looking at the spindle from the top down.

We will show for both types how they can be controlled.

This type of VFD uses two signals to control it. One signal switches the VFD on and off, and the other controls the spindle direction.

The table below shows how the controller uses the signals.

In the VFD manual, locate the Tool On and Direction connections.

In most cases, there is a connection overview diagram. The diagram in the manual will look very similar to the ones below.

The designation for these signals can vary; as you can see, it's possible that the designation is cryptic, like 'S1'. The manual will describe how to configure the signal to be Tool On.

Also, the designation for the 0-10V control voltage may differ. However, most images will show similar connections.

Before continuing, make sure you have the VFD configured manually and test the signals by hand

The connection between the inputs and the DCM signal does not indicate whether the DCM signal is 24V or ground. This can vary between manufacturers.

It's therefore advisable to use a small relay to connect the DCM signal and the inputs, and have the controller control these relays to avoid any issues with switching these signals.

Note that the relay should have an antiparallel diode to prevent spikes from relay switching from reaching the controller outputs. The relay that is used does not need to be very powerful, since almost no current will flow. An option is to use a DIN rail-mounted relay.

Below is an example of such a relay. In this case, it is a Phoenix Contact RIF-0-RPT-24DC/21 (SKU: 2903370).

The CNC720 has only an output for tool on but no signal for a tool direction output.



Before connecting the VFD to the CNC720spindle, program the VFD configuration parameters to match the spindle. Find the parameters that allow external control of the spindle through the inputs on the VFD, and the speed control voltage reference is set to 10V or the control type is set to PWM.



Both outputs on the CNC720 can be inverted, but keep in mind that it is recommended to wire the VFD in a way that the spindle is off when both outputs are off. Doing this will ensure the spindle shuts off if the controller fails.

Speed control can be done using either 0-10V or PWM. The CNC720 is capable of supplying either option. The most common is 0-10V, where 0V corresponds to the minimum RPM and 10V to the maximum RPM. When choosing PWM, you may need a pull-up resistor to achieve the upper voltage expected by the VFD. The CNC720 contains user-selectable pull-up resistors to simplify wiring. The usage of 0-10V voids the PWM1 output.





In the picture above, you can see what's inside on the right. Besides the relay, you also see the diode, and, as a bonus, an LED indicator that helps you check your wiring.





The outputs on the CNC720 are so-called 'Open collector outputs.







In the manual for the VFD, find the connections for Tool on and Direction, in most cases, there is a connection overview diagram. The outputs on the CNC720 feature relay outputs, these can be connected instead of the switches.

Speed control can be done using either 0-10V or PWM. The CNC720 is capable of supplying either option. The most common is 0-10V where 0 volts means minimum RPM and 10 volts means the maximum RPM. When choosing PWM, you may need a pull-up resistor to achieve the upper voltage expected by the VFD. The CNC720 contains user-selectable pull-up resistors to simplify wiring. The usage of 0-10V voids the PWM1 output.

Navigate to Setup -> Toolhead -> Toolhead and ensure that On/off output for the main toolhead is set to TOOL OUT.

When using the tool direction, set Direction output to AUX1 OUT.

Ensure that the PWM output setting is set to PWM1 OUT when using speed control.

The value entered in the Minimum RPM setting is used to correct programming errors where an S value is used that is too low.

The Maximum RPM setting is used to map the programmed RPM to a 0-10V or PWM value, The RPM entered here is the RPM the spindle turns at the full 10V or 100% PWM.

Setting the ramp-up and ramp-down delays will pause the execution when M3, M4, and M5 are called. This allows the spindle to reach its programmed position before executing the next line in the job file.

These tests ensure that the basic connections of the spindle are correct.

Here are some common issues and their solutions:



This VFD type connects to the controller using a connection for clockwise rotation (CW) and one for counter-clockwise rotation (CCW). The markings on your EdingCNC controller are named tool on and tool direction in case tool direction is not available, an aux output must be used. The Tool On output is used as for the CW signal and the Tool Dir is used as CC









*Consult the manual of your VFD to see the behavior of the spindle when both inputs are active. This is unintended and undefined behavior and will be avoided by the CNC720.