I have to support a BW TX300 V3 and am able to use Magic RDS 3 communicating Bidirectional with no difficulties. I can Read and Send / Test without any problems, via IP and/or RS232.
The RDS Ethernet 1 is configured to port 1000 by default, but you may need to turn it On in the web interface - there is no need to do any "logging in" prior to RDS communication.
The RDS board does not have the full range of commands supported so you may occasionally see !Ready
Some information about the BW transmitters on different firmware versions with RDS performance and system RDS commands is available online at
http://www.nealuk.com/bwtxv3.htmlRegards,
Neal