Add VLAN-tagging for QoS object (attribute 1)

Support of 802.1Q is directly linked to QoS attribute 1 "802.1Q Tag Enable".

CIP Volume 2 description of attribute 1 (Edition 1.33):
The "802.1Q Tag Enable" attribute enables or disables sending 802.1Q frames on CIP and  IEEE1588 messages. When the attribute is enabled, the device shall send 802.1Q frames for all CIP and IEEE 1588 messages. The 802.1Q priority value shall be as specified in Volume 2, chapter 3. A value of 1 shall indicate enabled. A value of 0 shall indicate disabled. The default value for the attribute shall be 0. A change to the value of the attribute shall take effect the next time the device restarts.

Note: devices shall always use the corresponding DSCP values regardless of whether 802.1Q frames are enabled or disabled.

Implementation/Requirements:

• The feature "VLAN tagging" shall be available for all V3 and V5 firmwares.
• QoS attribute 1 shall be disabled in the CIP object dictionary by default (no get/set access possible). 
• It shall be possible for the host application to activate QoS attribute 1. The default value of attribute 1 shall be 0 (802.1Q tagging disabled).
• If QoS attribute 1 is activated in the object dictionary, it shall be possible to enable/disable 802.1Q tagging for IEEE 1588 messages by writing value 1/0 to attribute 1. This shall be possible from the network AND from the host application side.
• QoS shall be part of the remanent data in order to survive power cycles.
• If the attribute 1 value was changed from the network side, the change shall be applied not before the next power cycle/identity reset.
• If attribute 1 value is 1 (enabled) all transmitted IEEE 1588 and CIP messages shall be VLAN tagged.
  • Implicit and Explicit CIP messages
  • All types of PTP messages (general and event)
• For VLAN tagged frames, the VLAN priority (802.1D Priority) shall adhere to table 3-7.5 "Mapping CIP Traffic to DSCP and 802.1D" (CIP Volume 2, Edition 1.33)

Documentation:

• Extend API Manual to reflect the new functionality.
• Datasheet: will be adapted in firmware project(s)
• Migration note: no change required

Links and References

• EtherNet/IP Specification: CIP Volume 2, Edition 1.33
  • Section 3-7 "Quality of Service (QoS) for EtherNet/IP Messages"
  • Section 5-7 "QoS Object" (especially sub-section 5-7.4.1 "802.1Q Tag Enable – Attribute 1")