6K Software - Why Do I Get A *B and *C when I Turn on My 6K?

When the DRPCHK is set to something other than 0 (zero) for a port, the controller sends out a *B and *C intended for an RP240. This is to check for the existence of an RP240 in the system. DRPCHK0 is the default for Port 1 and DRPCHK3 is the default for Port 2.

This may be changed using the PORT and DRPCHK commands.