Description

The Siemens 6ES7390-0AA00-0AA0 is a spare bus connector (commonly referred to as a U-connector) explicitly designed for the SIMATIC S7-300 modular automation system . While often overlooked, this small plastic component is the silent workhorse that physically and electrically bridges the backplane bus between the CPU, power supply, and all I/O modules, forming the backbone of a cohesive control system .

As an official spare part from Siemens, the Siemens 6ES7390-0AA00-0AA0 is not a “feature-rich” module but a mission-critical mechanical accessory. It ensures that data, addresses, and control signals flow seamlessly across the mounting rail, allowing the system to function as a single, unified PLC . Its simple, tool-free U-shape design is an engineering marvel that guarantees robust connectivity with minimal installation effort.

 

Application Scenarios

In a bustling chemical processing plant, a maintenance engineer rushed to the field after an S7-300 rack inexplicably lost communication with half of its I/O modules. Upon inspection, a faint crack was found on the bus connector between the CPU and the first signal module—a small piece of plastic costing mere dollars, but its failure had halted an entire production line. The engineer reached into the spare parts cabinet, retrieved a Siemens 6ES7390-0AA00-0AA0, and replaced the broken component in seconds . After a short power cycle, the system was fully operational. This “black clip” at the rear of the card, officially designated as the Siemens 6ES7390-0AA00-0AA0, had proven that sometimes the smallest parts are the most critical to system availability .

 

Parameters

Main Parameters	Value/Description
Product Model	6ES7390-0AA00-0AA0
Manufacturer	Siemens
Product Category	Bus Connector / Spare Part
Product Type	U-Connector (Mechanical & Electrical Bridge)
Compatibility	SIMATIC S7-300 (CPU, SM, FM, CP, PS modules)
Contacts	40-pin (Gold-plated for low resistance)
Connection Type	Backplane Bus (Insulation displacement for tool-free connection)
Weight	Approx. 13 g (Ultra-lightweight)
Dimensions	Minimal (Fits behind modules)
Installation	Tool-free, Direct insertion into module rear
Lifecycle Status	Spare part, Active support

The Siemens 6ES7390-0AA00-0AA0 is a “one-size-fits-all” solution for the S7-300 platform. The gold-plated contacts ensure signal integrity and corrosion resistance, while the durable plastic housing provides mechanical stability in harsh industrial environments .

 

Technical Principles and Innovative Values

The Siemens 6ES7390-0AA00-0AA0 represents a fundamental principle in industrial automation design: making complex connectivity simple and robust.

• Innovation Point 1: The “Zero-Tool” Installation Philosophy. True to the S7-300’s modular design, the Siemens 6ES7390-0AA00-0AA0 eliminates the need for screws or tools. The connector is physically inserted between the CPU and the first module, or between adjacent modules, on the DIN rail . As modules are slid together and locked, the bus connector’s “U” shape guides the mating process. Its internal contacts utilize an insulation-displacement technique, automatically piercing through the module’s protective coating to establish a secure and reliable electrical bond .
• Innovation Point 2: Passive Reliability. The Siemens 6ES7390-0AA00-0AA0 is purely a passive component containing no electronics. This is a key advantage; there is no firmware to update and no active component to fail electronically. The only failure modes are physical damage (cracks or broken clips) or contamination of contacts . This simplicity ensures that, if properly handled, the Siemens 6ES7390-0AA00-0AA0 provides a lifetime of reliable service.
• Innovation Point 3: Standardized Interconnect. The Siemens 6ES7390-0AA00-0AA0 is used for all module types in a standard S7-300 setup—whether connecting the CPU to a digital input module, a high-speed counter, or a communication processor . This standardization simplifies inventory; you need only one part number for all your connection needs across an entire plant’s S7-300 fleet, a significant logistical advantage for maintenance departments.