Create bsc(4) and/or hdlc(4) drivers to hang under the time-multiplexed scc(4) bus and work out how best to share the scc(4) bus in a time-multiplexed manner. A good approach would be to activate a resource (all resources) on open(2) and to deactive it (them) on close(2). This would make use of the sharing and waiting facility already present in RMAN and would naturally cause one driver to block/sleep in open(2) while another driver on the same bus has the device open already.