PDO Restrictions and Compiler Errors

Restrictions for AKD Devices

The KAS-IDE compiler enforces these restrictions to the editable PDOs for AKD devices:

  • The maximum byte count for the content of an individual PDO (both selected and unselected) is 8 bytes.
    • The PDO content Size field is highlighted in red if the Editable PDO content size is greater than 8 bytes.
  • The total maximum byte count for the content of all Tx PDOs (both selected and unselected) is 32 bytes.
  • The total maximum byte count for the content of all Rx PDOs (both selected and unselected) depends upon the firmware.

    Firmware Version

    Byte Limit

    Notes

    v1-17 or later

    32 bytes

    This is the byte limit when the EtherCAT parameter ECAT.LEGACYREV is set to 0 (zero).

    v1-16 or later

    20 bytes

    This is the byte limit when the EtherCAT parameter ECAT.LEGACYREV is set to 1.

    v1-15 or earlier

    20 bytes

     

  • The total byte count for the content of all selected Tx PDOs must be even.
    • This does not apply to AKD2G devices.
  • The total byte count for the content of all selected Rx PDOs must be even.
    • This does not apply to AKD2G devices.

  • The object 0x00 can be used to pad the PDO to get the total byte count to an even value.

  • Compiler errors are generated if these restrictions are not met.

These are example compiler errors:

In AKD_1, the size of Rx PDO 0x1600 is greater than the limit: 9 > 8
In AKD_1, the total byte count for all editable Rx PDOs is greater than the limit: 39 > 32
In AKD_1, the total byte count for all editable Rx PDOs that are assigned is not even: 29

Restrictions for AKD2G Devices

The KAS-IDE compiler enforces these restrictions to the editable PDOs for AKD2G devices:

  • PDOs have a size constraint of 128 bytes per PDO.
  • The total maximum byte count for the content of all Rx PDOs (both selected and unselected) is 512 bytes.
    • [(128 per PDO) x 4 = 512 bytes].
  • The total maximum byte count for the content of all Tx PDOs (both selected and unselected) is 512 bytes.
    • [(128 per PDO) x 4 = 512 bytes].
  • Based on the Sample Rate / Cycle Time, there is a limitation to the number of PDOobjects:

    • Sample Rate

    Cycle Time

    Max. PDOs

    4kHz

    250μs

    14 Rx, 14 Tx

    2kHz

    >500μs

    30 Rx, 30 Tx

Restrictions for Kollmorgen Essentials Drive Devices

The KAS-IDE compiler enforces these restrictions to the editable PDOs for Kollmorgen Essentials Drive devices:

  • PDOs have a size constraint of 128 bytes per PDO.
  • Rx PDOs
    • The maximum number of Rx PDOs supported is 14.
    • The total maximum byte count for the content of all Rx PDOs (both selected and unselected) is 512 bytes.
      • [(128 per PDO) x 4 = 512 bytes].
  • Tx PDOs
    • The maximum number of Tx PDOs supported is 14.
    • The total maximum byte count for the content of all Tx PDOs (both selected and unselected) is 512 bytes.
      • [(128 per PDO) x 4 = 512 bytes].

Restrictions for All Other Devices

The KAS-IDE compiler enforces the following restriction to the editable PDOs for all devices:

  • The maximum byte count for the content of an individual PDO (both selected and unselected) is 64 bytes.

Compiler errors will be generated if these restrictions are not met. Example compiler errors:

In Device_1, the size of Tx PDO 0x1A16 is greater than the limit: 66 > 64