PROBLEM TO BE SOLVED: To provide a data acquisition device configured to acquire input-output data exchanged on a field network without increasing load of resources of the field network and a master controller.SOLUTION: At a position capable of receiving all the MAC frames transmitted from a master controller 21 to slave devices 22 to 24 and all the MAC frames transmitted from the slave devices 22 to 24 to the master controller 21, a data acquisition device 10 is connected with real time Ethernet without transmitting any data, makes a storage section store input-output data extracted from the MAC frame, and transmits the input-output data stored in the storage section to a data management device 50.SELECTED DRAWING: Figure 1
