View Serial Numbers for a Physical Device Primary and secondary serial numbers of managed physical devices can be displayed by enabling hidden columns in the Managed Devices table. Note:Serial number information is pulled from a physical device through SNMP. Virtual devices return a value of N/A. Expand the Device Manager slider and click Devices. In the Managed Devices pane, click on the right side of a column header. The arrow icon appears with a drop-down menu. Mouse over the Columns selection and click and the column options that you want to enable: Primary Serial Num—Enables the Primary Serial Number column in the Managed Devices table. Secondary Serial Num—Enables the Secondary Serial Number column in the Managed Devices table.