QoS

Open the Page

Access the QoS (quality of service) page from the Diagnostics tab (Menu → Services → QoS):

NOTE:

Configure the QoS in Control Expert.
Click Detail View to expand the list of parameters.
This page is updated every 5 seconds.

Service Status

This table shows the possible states for the Service Status:

Status	Description
Running	The service is correctly configured and running.
Disabled	The service is disabled.
Unknown	The status of the service is not known.

Diagnostic Information

When you enable QoS, the module adds a differentiated services code point () tag to each Ethernet packet it transmits, thereby indicating the priority of that packet:

Field	Parameter	Description
Precision Time Protocol (see note)	DSCP PTP Event Priority	PTP time synchronization.
Precision Time Protocol (see note)	DSCP PTP General	PTP general.
EtherNet/IP Traffic	DSCP Value for I/O Data Scheduled Priority Messages	Configure the priority levels to prioritize the management of data packets.
EtherNet/IP Traffic	DSCP Value for Explicit Messages
Modbus/TCP Traffic	DSCP Value for I/O Messages	—
Modbus/TCP Traffic	DSCP Value for Explicit Messages	—
Network Time Protocol Traffic	DSCP Value for Network Traffic	—
NOTE: The Precision Time Protocol QoS attributes are 2 and 3 (class 48h, instance 1). Use these attributes to obtain QoS values for the Precision Time Protocol.

Considerations

Take measures to effectively implement QoS settings in your Ethernet network:

Use only network switches that support QoS.
Apply the same DSCP values to all network devices and switches.
Use switches that apply a consistent set of rules for handling the different DSCP values when transmitting and receiving Ethernet packets.