Time scheduling method and scheduler for a modular engine that negotiates among modules timing offers which include a timing range

Abstract

Disclosed are a time scheduling method and scheduler for a modular engine, e.g. a sheet handling engine. Interaction between the modules (e.g., 12, 14, 16, 18) of the engine involves an output from one module being delivered as an input to another module. The engine has at least one module (e.g., 12) that does not need an input from another module for performing a first action. The method comprises the allocation of a time to each action to be performed by the modules on the basis of information on the current status and timing constraints of the respective modules, wherein each module allocates the timings for its own actions by sending a timing offer (e.g., F[OK, . . . , . . . ]) to the module to which the output has to be delivered and receiving from that module a message (e.g., B[OK, . . . ]; B[NOT OK, . . . ]) accepting or rejecting the offer. The timing offer is based on the internal status and timing constraints of the module itself and, if an input from another is needed, on a timing offer from that module.