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

    4 kHz

    250 µs

    14 Rx, 14 Tx

    2 kHz

    >500 μs

    30 Rx, 30 Tx

Restrictions for Kollmorgen Essentials Drive and KLD Devices

The KAS-IDE compiler enforces these restrictions to the editable PDOs for Kollmorgen Essentials Drive and KLD 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 are generated if these restrictions are not met.

Example compiler error:

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