In some examples, a controller may include a processing resource and a memory resource storing non-transitory machine-readable instructions that are executed to cause the processing resource to direct a clock signal of an imaging device to a fill port via a detection circuit of the imaging device, determine based on a state of a switch included in the detection circuit whether the fill port is open or closed, determine based on the state of the switch indicating the fill port is closed a status of the fill port, and in response to the status of the fill port being closed, determine based on a voltage of the clock signal whether the fill port is connected to a colorant container.