A memory subsystem includes logic buffer coupled to a command bus between a memory controller and a memory device. The logic buffer detects that the memory controller places the command bus in a state where the memory controller does not drive the command bus with a valid executable memory device command. In response to detecting the state of the command bus, the logic buffer generates a signal pattern and injects the signal pattern on the command bus after a scheduler of the memory controller to drive the command bus with the signal pattern.