Provided is a communication control system in which a control device and one or a plurality of control target devices are connected through a network, wherein at least one of the plurality of control target devices includes a sub master and a sub slave to be synchronously controlled with each other, and the control device includes a storage unit storing each pieces of information on a synchronization period for synchronizing with the control target device, communication periods, and mutual communication control information for mutually communicate in a mutual communication period shorter than the synchronization period, a calculation unit calculating a control command for commanding an operation in synchronization with the control target device for each control target device, and a communication control unit transmitting the control command including the mutual communication control information to the sub master and the sub slave of the at least one control target device.

Provided is a communication control system in which a control device and one or a plurality of control target devices are connected through a network, wherein at least one of the plurality of control target devices includes a sub master and a sub slave to be synchronously controlled with each other, and the control device includes a storage unit storing each pieces of information on a synchronization period for synchronizing with the control target device, communication periods, and mutual communication control information for mutually communicate in a mutual communication period shorter than the synchronization period, a calculation unit calculating a control command for commanding an operation in synchronization with the control target device for each control target device, and a communication control unit transmitting the control command including the mutual communication control information to the sub master and the sub slave of the at least one control target device.

An operation monitoring device monitors operations of machining devices in a machining line. Information on a workpiece stocker that constitutes the machining line is acquired, and a current workpiece stock number for the workpiece stocker is updated based on the acquired information. The necessity of change of machining speeds of the machining devices constituting the machining line is determined based on the current stock number for the workpiece stocker. Based on the result of the determination, change of the machining speeds is commanded to the machining devices located before and behind the workpiece stocker in the machining line.