Make sure you aren't confusing the physical T-taps or Y-taps with the logical 'Nodes', which are the actual automation devices.
Understand also that devices with two BNC connectors, like the 1794-ACNR15 adapter, have two separate channels (A and B). The signal doesn't pass from one channel to another in a daisy-chain.
A ControlNet network with one 1756-CNB and one 1794-ACN(R)15 adapter must physically have two Taps, two Terminators, and a trunk cable.