PURPOSE: To add easily instrumentation information without remarkable remodeling of existing equipment, by constituting the system so that the plural sets of instrumentation information are switched at each group and an instrumentation word is transmitted while being added with group identification information.
CONSTITUTION: A drive switching circuit 11 operates sequentially relays RY1∼ RYm by a prescribed time (t). When the relay RY1 is operated at first and contacts r10∼r12 are brought into an on-state, a reference voltage V1 is applied to an individual input circuit 4-0 from a reference voltage generator 10 and transmitted as group identification information, and the instrumentation information of the 1st group is applied respectively from an input terminal A11 to an individual input circuit 4-1, from an input terminal A21 to an individual input circuit 4-2 and from an input circuit An1 to an individual input circuit 4-n sequentially and transmitted as an instrumentation word. When the time (t) is elapsed, the circuit 11 restores the relay RY1, activates the relay RY2 to close contacts r20∼r2n, and a reference voltage V2 and the identification information and the instrumentation information of the 2nd group are transmitted sequentially from terminals A12∼An2 to circuits 4-1∼4-n. The instrumentation information may be added only to the relays RY, the generator 10 and the circuit 11.
WATANABE KEIJI
MARUYAMA ETSUO
