I have this control IO port on a machine panle. I know a little of reading electrical diagrams. Could some friend help me about it. I can not understand where the machine can supply current as a source and where it must be supplied from an external source. Is it correct that the port supplies voltage to the inputs with A12 common? Is it also correct that the port must be supplied from an external source at output terminals B1 to B12 in order for the outputs would function properly?