３ - ２ System Configuration The main hardware configuration using the NJ/NX troubleshooter is shown in the following figure. NA-series Display control Event control EtherCAT slave Additional Information Device to be detected Only NJ-series can connect Units to I/O bus. 12 NJ/NX-series CPU Unit I/O bus (CJ Unit) I/O bus (CJ Unit) EtherCAT slave coupler Unit Unit