Two path system in Fanuc CNC

When you are using two paths in the FANUC CNC system, there will be more than one spindle motor and three or more servo motors. For this, you need to set up the FANUC CNC system for two-path operation, which means you need to configure two paths system. Do wiring for multi-spindle and multi servos. You need to set some parameters and also do write PLC programs for the two-path system.

Let me show you which are all parameters, you will have to set for a two-path FANUC CNC system.

Setting for spindle motor and drive:

Connection diagram for multi spindles with two paths CNC:

Parameter number 982 is used to configure the spindle in two path CNC system

Set the path number to which spindle is assigned.

You need to set path number for each spindle, that spindle belongs to which path number.


Case 1:

Case 2:

Case 3:

Case 4:

Set the spindle amplifier number as per following parameter number 3717

Motor number to each spindle
0No spindle amplifier is connected
1Spindle amplifier number 1 is used
2Spindle amplifier number 2 is used
3Spindle amplifier number 3 is used

Write PLC program for two-path which having multi-spindle motors.

What changes you will have to do in the FANUC PLC program to enable all spindles in two path CNC machines?

  • You need to select HEAD 1 and HEAD 2 for the two-path system, means if you select HEAD 1, path 1 is selected and if you select HEAD 2, path 2 is selected.
  • HEAD I and HEAD 2 are selected by switching ON ‘G’ signal G63.0
G signalStatusHEADPATH
G63.00HEAD 1 SelectedPath 1 Selected
G63.01HEAD 2 SelectedPath 2 Selected

Ladder program for path selection shown below:

If you press Path 2 button on the operator panel, G63.0 gets ON, means Path 2 selected, or else if you do not press default path 1 is selected.

How to use ‘G’ signals and ‘F’ signals in two paths FANUC CNC system?

The ‘G’ signals and ‘F’ signals of HEAD 2 (path 2) are different from HEAD 1 (path 1). Simply add ‘1000’ to the address of HEAD 1 (path 1).

Example:  The ‘G’ signal G8.4 is used in HEAD 1 and equivalent HEAD 2 signal is G1008.4

Example:  The ‘F’ signal F0.6 is used in HEAD 1 and equivalent HEAD 2 signal is F1000.6

Servo motor enable and setting in two paths FANUC CNC system

Set the following parameter to assign how many axes connected in each path.

8130Use this parameter to set the number of axes in each path

Configure axes for two-path system using below mentioned parameter number 981:

981Set path number to which axis is assigned


Assume that your two paths CNC machine having a total six numbers of axes. You need to add three axes in path 1 and the other three axes in path 2, and then you need to set the value as below mentioned in 981.

1Path 1, axis 1
1Path 1, axis 2
1Path 1, axis 3
2Path 2, axis 1
2Path 2, axis 2
2Path 2, axis 3

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