  This paper considers transfer functions in consensus systems where agents
have identical SISO dynamics of arbitrary order. The interconnecting structure
is a directed graph. The transfer functions for various inputs and outputs are
presented in simple product forms with a similar structure of the numerator and
the denominator. This structure combines the network properties and the agent
model in an explicit way. The link between a higher-order and a
single-integrator dynamics is shown and the polynomials of the transfer
function in the single-integrator system are related to the graph properties.
These properties also allow to generalize a result on the minimal dimension of
the controllable subspace to the directed graphs.
