CPU 416-3 PN/DP — ATEX-rated S7-400 controller
The 6ES7416-3XS07-0AB0 is a Siemens SIMATIC S7-400 CPU 416-3 PN/DP controller. It carries ATEX II 3G Ex nA IIC T4 Gc certification, meaning it is approved for installation in Zone 2 gas hazardous areas where non-sparking equipment (Ex nA) is permitted, with a surface temperature limit of T4 (135 °C). This makes it suitable for oil-and-gas, chemical, or pharmaceutical panels where a standard PLC would not pass the area classification review. The CPU supports 244 bytes of process input and 244 bytes of process output, with an overall connection limit of 96 — enough for a medium-sized distributed I/O network over PROFINET or PROFIBUS. It handles CFC, SCL, STL, FBD, LAD, and GRAPH programming languages, giving the integrator flexibility across legacy and modern codebases.
Integration constraints — FM, RDREC, WRREC
The FM (function module) count is limited by the number of free slots in the rack and the number of available connections — no hard cap beyond the physical backplane. For RDREC (SFB 52) and WRREC (SFB 53), the CPU supports 8 per interface, with a total of 32 across all external interfaces. This matters when planning multiple PROFIBUS or PROFINET segments with distributed I/O requiring consistent data records. The CPU occupies a 50 mm wide slot on the S7-400 rack, with a depth of 219 mm and height of 290 mm. Verify clearance in the enclosure before specifying.