Counting the COVs. CGP Electronics TP-42

Figure 27: MSTP Master Summary Showing Baud Rates

Counting the COVs

You can check the COV report rates on the main device object Diagnostics tab of each device that supports this measurement. The two attributes are COV Tx Rate and COV Rcv Rate. The NAE COV Rcv Rate is the total for all connected networks including the Ethernet and should not exceed 500 per minute. The COV Tx Rate counts only the reports originated by this device. Double clicking on the Trunk object at the top of the tree on the engineering tab displays a list of devices, and the COVs TX, from devices that report this information. For more information on these attributes, refer to the NAE Object and the MS/TP Field Device Object in the Metasys system Help.

Disabling a Device on the Bus

If a device is causing communication problems, the Disable command from the Metasys system UI allows you to take the device offline. Once disabled, the device no longer sends or receives data, but remains in the token loop to maintain bus integrity and pass the token to the next device.

This procedure only prevents data related problems and has no effect on addressing or token loop problems.

Note: This command works on specific devices; it is not available on TEC Thermostat Controllers and may not be available on third-party devices.

To disable a device on the bus:

1. On the navigation tree, right-click the device you want to disable and select Commands from the pop-up menu.

A dialog box appears for the device.

2. Select Disable and click Send. The device goes offline and a red X appears in front of the device in the navigation tree.

MS/TP Communications Bus Technical Bulletin: Appendix: Maximizing and Troubleshooting the MS/TP Bus 56