SINUMERIK 840D是西门子公司20世纪90年代推出的高性能数控系统。它保持西门子前两代系统SINUMERIK 880和840C的三CPU结构：人机通信CPU（MMC-CPU）、数字控制CPU（NC-CPU）和可编程逻辑控制器CPU（PLC-CPU）。三部分在功能上既相互分工，又互为支持。在物理结构上，NC-CPU和PLC-CPU合为一体，合成在NCU（Numerical Control Unit）中，但在逻辑功能上相互独立。相对于前几代系统
6FC5357-0BB11-0AE0 NCU571.2数控主板
6FC5357-0BB11-0AE1 NCU571.3数控主板
6FC5357-0BB12-0AE0 NCU571.4数控主板
6FC5357-0BB13-0AA0 NCU571.3数控主板
6FC5357-0BB13-0AA1 NCU571.3数控主板
6FC5357-0BB14-0AA0 NCU571.4数控主板
6FC5357-0BB15-0AA0 NCU571.5数控主板
6FC5357-0BB21-0AE0 NCU572.2数控主板
6FC5357-0BB21-0AE1 NCU572.2数控主板
6FC5357-0BB22-0AE0 NCU572.3数控主板
6FC5357-0BB23-0AA0 NCU572.3数控主板
6FC5357-0BB23-0AA1 NCU572.3数控主板
6FC5357-0BB23-0AE0 NCU572.4数控主板
6FC5357-0BB24-0AA0 NCU572.4数控主板
6FC5357-0BB25-0AA0 NCU572.5数控主板
6FC5357-0BB31-0AE0 NCU573.2数控主板
6FC5357-0BB33-0AA0 NCU573.3数控主板
6FC5357-0BB33-0AA1 NCU573.3数控主板
6FC5357-0BB33-0AE0 NCU573.2数控主板
6FC5357-0BB33-0AE1 NCU573.2数控主板
6FC5357-0BB33-0AE2 NCU573.3数控主板
6FC5357-0BB33-0AE3 NCU573.3数控主板
6FC5357-0BB34-0AA0 NCU573.4数控主板
6FC5357-0BB34-0AE0 NCU573.4数控主板
6FC5357-0BB34-0AE1 NCU573.4数控主板
6FC5357-0BB35-0AA0 NCU573.5数控主板
6FC5357-0BB35-0AE0 NCU573.5数控主板
6FC5357-0BB52-0AE0 NCU572.2数控主板
6FC5357-0BB53-0AE1 NCU573.2数控主板
