Siemens 6ES73921AM000AA0 Programmable Logic Controller Accessory. SIMATIC Connector Front Series: S7-300 For Use With: Signal Module with Screw Contact 125 mm H x 21.6 mm W x 40.9 mm D. Additional Description: SIEM-6ES73921AM000AA0 CONNECTOR FRONT SCREW S7300 40PIN 32PT. Catalog Description: SIMATIC s7-300front connector 392 with screw contacts 40-pin.