How do I create my own modbus device template in order to add new devices using the administration dashboard?
Create my own device template
There are a ton of ways to do this.
Here's a video on using CSV to create large numbers of points: https://help.infiniteautomation.com/bulk-importing-data-points
Here's a thread about using the template configuration module to do it: https://forum.infiniteautomation.com/topic/3216/template-import-json-markup-example
Here's a thread using a script to import event detectors onto points: https://forum.infiniteautomation.com/topic/3708/a-script-jsonemport-example
The second two are based off JSON, which is also what it would be used for the API, as in this thread: https://forum.infiniteautomation.com/topic/3060/mango-rest-api-how-to-create-data-sources-data-points
There's also a copy button on data sources in the old UI (use the link from the data sources page to the legacy data sources page, or navigate to /data_sources.shtm). I suspect it will appear in the new UI fairly soon:
I probably overlooked a few options...