function [bonds,status] = ES_cause(bonds);
% Causality for ES component

%SUMMARY ES: converts thermal pseudobond to true bond and vv
%DESCRIPTION Port [e]: temperature (T) / enthalpy flow (E) bond
%DESCRIPTION Port [s]: temperature (T) / entropy flow (S) bond



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% %% Version control history
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% %% $Id$
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% Copyright (c) P.J. Gawthrop, 1997.

status = -1;

% Check that there are exactly two bonds.
if check_bonds(bonds,2,'ES')==0
  return
end

% Same causality as TF
[bonds,status] = TF_cause(bonds);