Siemens 6ES7921-3AB20-0AA0 SIMATIC TOP Connect Front Connector 40-Pole Screw PLC Connection Module

The Siemens 6ES7921-3AB20-0AA0 is a SIMATIC TOP connect front connector module that replaces the standard 40-pole front connector on S7-300 digital I/O modules wired for 32 channels. It routes signals through two 16-pole IDC cable connections and feeds power through screw-type terminals rated 24 V DC, 1 A per contact, torqued to 0.4-0.7 N·m. It plugs directly into the module in place of the factory connector.

Technical Specifications

Certifications & Standards

• cULus

Selection Notes

The 40-pole count matches I/O modules wired with two 16-pole IDC cables, so it fits 32-channel digital modules rather than the 16-channel versions that only need a 20-pole connector. Screw terminals give a documented 0.4-0.7 N·m tightening torque on the L+/M supply connection, useful where the build sheet requires a recorded torque value; choose the spring-terminal version instead when modules are swapped often and tool-free wiring speed matters more.