The 8730 external switch interface allows the use of mechanical foot switches or other normally open switches to control a S-link bow thruster. In addition it allows for connecting the 8980/8985 radio remote control. The 8730 sends proportional thrust on the S-link bus. This is 70% as default. This value can be changed on an PJC212, PJC211, PJC222 or PJC221 panel. Se manual of the panel for more details. If you have two thrusters bow and stern, then you need two 8730. One 8730B for bow and one 8730S for stern. You can change instance of 8730 B & S with
a panel, see manual for panels for how to changing instance of 8730 B & S.