Records created for a custom module can be linked to managed entity instance (devices, assets, or locations). This is done by selecting the appropriate record in their corresponding field.
A lookup field for the default custom modules is available in all managed entity instances. Additionally, lookup fields for user-defined custom modules can be added to an instance by adding the field to the respective model.

Note: Only records created for a custom module will be available for association.
To associate a record with an instance,
Access the End Application.
Select Devices > Devices in the left pane.You can select Assets to associate a record to an asset or Location to associate a record to a location.
Click the name of the device you want to associate the record to. This opens the device's information page. For this illustration, the device: My RPi is considered.
Click Actions > Edit Details. This opens the device details form.
Click on the lookup field (scroll down if necessary to find the field) and select the custom record in the required lookup file. For this illustration, Zylker Industries is selected as the Vendor for the device instance.
Note: Lookup Field for user defined custom modules must be added to the model on which the instance is based on for it to be available in the details page.
Click Update. The selected record will now be associated with the managed entity instance.