SERCOS drives with position control in the CNC

SERCOS drives with position control in the CNC

The position control of SERCOS drives is normally performed in the drive. Alternatively, it is possible to use the operation mode “velocity control“ in the drive and to calculate the position control loop in the CNC.

For position control in CNC the following requirements must be fulfilled:

• The operation mode velocity control is active in the SERCOS-drive.
• The command velocity is transmitted to the drive (S-0-0036 is part of the cyclic telegram)
• Actual positions are transmitted from the drive to the CNC (S-0-0051, S-0-0053 or S-0-0386 are part of the cyclic telegram)
• The operation mode (s. P-AXIS-00320) of the axis must be set to CNC-position control (CNC_POSITON_CONTROL)

The following restrictions exist in comparison to the position control in the drive, if the position control is performed in the CNC:

• A drive-controlled reference point traverse is not possible. Instead of the drive controlled RPT a CNC-controlled reference point traverse is used.
• A zero-pulse search is with the CNC-controlled reference point search for SERCOS drive is presently not supported. The axis parameter P-AXIS-00084 (homing_without_zero_pulse) must therefore be set to one.
• The delay between the command and actual values is not accounted in the calculation of the position lag (s. P-AXIS-00191).