Geofrey? (Or whatever "friendly" name you would like to use...)
For the problem where JMRI is unable to communicate with the SE8c:
See for information on the ways in which the PR4 can be used with JMRI.
You probably have used JMRI with the PR4 as a "standalone programmer", where the decoder is on a programming track which is connected to the PR4. This is the first usage mode in the first table shown in the web page mentioned above. In that mode, the PR4 does not communicate with LocoNet.
For communication with the SE8C, the second mode in the first table is the one you want.
Most users will implement one "configuration profile" configured to communicate with the PR4 in "standalone programmer" mode, and one configuration profile to communicate with the PR4 in "LocoNet interface" mode. When you have two (or more) separate configuration profiles, JMRI will start-up with a chooser window so that you can select one of the profiles (or it will default to the last-used profile if you don't select one within 10 seconds).
Note that JMRI can be used for programming decoders via the command station's programming track connections when used with a PR4 "LocoNet interface" connection. But because you have a DB150, you would be limited to write operations using that mechanism, since the DB150 does not support CV reads on its programming track.
As such, with the configuration shown above, it is appropriate to switch to the "PR4 standalone programmer" profile for programming, and switch to the "PR4 LocoNet Interface" profile for signaling development and operation.
Regards,
Billybob
