Does adding an NCA-2 annunciator to the NFS2-640 require an NCM network module?

Whether an NCM is required depends on if the system is stand-alone or networked. For a stand-alone NFS2-640 system, the NCA-2 can connect directly to the CPU2-640 and does not require an NCM (Page 4) [1].

However, on network systems consisting of two or more nodes, the NCA-2 requires either a standard Network Communication Module or a High-Speed Network Communication Module (Page 4) [1].

For direct mounting in stand-alone applications, use the NCA/640-2-KIT (Page 6) [1].