In some examples, a fluid ejection device includes a communication interface comprising a plurality of communication channel circuits capable of communicating over respective communication channels, and a configuration controller, responsive to an input, to selectively activate at least one communication channel circuit of the plurality of communication channel circuits, wherein different inputs to the configuration controller are to cause selective activation of different numbers of the plurality of communication channel circuits. The fluid ejection device further includes a nozzle controller responsive to data received through the activated at least one communication channel circuit to cause activation of at least one corresponding nozzle to eject fluid.