This device supports two protocols. One is BACnet MS/TP and the other is LinkNet (Delta’s own protocol).
When the product is shipped the internal jumper is set to LinkNet. Despite this BACnet MSTP is active and if you connect a MSTP client you can read and write the BACnet objects. What you cant do until you change the jumper is discover the device. It appears the only effect of the jumper is to enable the reply to a who-is.
Did you know that with the CAS BACnet Explorer you can add a device manually and then discover its objects and properties. Using this feature the DFM-200 was ‘discovered’ even with the protocol selection jumper in the wrong position.