Yes, although this requires that Bus A be connected to Bus B (through a transformer-coupled bus with proper termination).
NOTE THAT THIS IS AN INVALID BUS CONNECTION – VIOLATES PARAGRAPH 4.6.3 OF THE MIL-STD-1553 SPECIFICATION.
You can find a sample program using Alta products and the AltaAPI via ADT_L1_1553_ex_BIT_BusAB_Wrap (587 downloads )