Just added some more new shapes for grafcet diagrams following a user request over on the MS user forums.
http://www.paulherber.co.uk/visio-grafcet/ (http://www.paulherber.co.uk/visio-grafcet/)
These shapes are now free and the URL moved to:
http://www.paulherber.co.uk/articles/visio-articles/grafcet-diagrams/ (http://www.paulherber.co.uk/articles/visio-articles/grafcet-diagrams/)