0 ExtBUSY         Front-panel BUSY input
 1 ExtBUSYout      Bit 0 masked by EnExtBUSY
 2 IntBUSY         Internal BUSY only
 3 BUSYout         OR of all enabled BUSYs (output)
 4 BurstBUSY       BURST sequence running
 5 SeqBUSY         Sequencer running
 6 SinkBUSY        Sink running
 7 RODBUSYout      Masked OR of ROD BUSYs (output)
 8 TTCClkON        TTC system clock running
 9 SaClkON         Stand-alone clock running
10 RunMode         TTC system operation
11 SaMode          Stand-alone operation
12 -               reserved = 0
13 -               reserved = 0
14 TestBUSY        Stops Int and Ext triggers
15 LaserInterlock  Laser Interlock on