That controller was the "stock" controller on the first factory solar panel builds in the 400. After a few months, it was superseded by one of the Victron units. If you just picked up a previously used 400 with the big AGM setup, it is most likely already configured for that battery type. Some info and discussion about it here:
There is a free Android app "Grape Solar" available on the Google Play Store that can be used to connect via Bluetooth to that HP2440 solar controller:
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Scroll down to # 10 to select battery type.
https://play.google.com/store/apps/details?id=com.ruijing.grapesolar