So, I tried 4 different scenarios.
1) use the connection without the PSU turned on
19:24:40.713 : No start signal detected - forcing start
19:24:40.728 : N1 M11034
19:24:40.728 : N2 M11536
19:24:40.728 : N3 M10536
19:24:40.728 : N4 M11435
19:24:40.728 : N5 M111 S698
19:24:40.728 : N6 T060
19:24:40.728 : N7 M2022
19:24:40.728 : N8 M8019
19:24:43.836 : N9 M10546
19:24:46.898 : N10 M10522
2) Use the connection while the PSU is turned on
19:25:26.984 : Communication timeout - reset send buffer block
19:25:26.984 : N11 M10523
19:25:26.991 : N12 G1 Z1 F1007
19:25:26.991 : N13 G1 Z1 F1006
19:25:26.991 : N14 G1 Z1 F1001
19:25:29.866 : N15 M10519
19:25:32.927 : N16 M10516
19:25:36.012 : N17 M10517
19:25:39.120 : N18 M10530
3) Use the connection after hitting the reset button on the radds
19:26:19.207 : Communication timeout - reset send buffer block
19:26:19.207 : N19 M10531
19:26:22.282 : N20 M10521
19:26:25.358 : N21 M10520
19:26:28.465 : N22 M10523
19:26:31.550 : N23 M10522
19:26:34.610 : N24 M10517
19:26:37.617 : N25 M10516
19:26:40.693 : N26 M10519
19:26:43.706 : N27 M10518
4) Use the connection after hitting the reset button on the DUE
19:27:23.790 : Communication timeout - reset send buffer block
19:27:23.790 : N28 M105*29
19:27:26.765 : N29 M10528
19:27:29.819 : N30 M10520
19:27:32.826 : N31 M10521
19:27:35.902 : N32 M10522
19:27:38.956 : N33 M10523
19:27:41.969 : N34 M10516
19:27:44.980 : N35 M105*17
All four result in having: "1 command waiting in queue"