Description
The Siemens 6ES5376-1AA21 is a 376-series memory submodule manufactured by Siemens, designed as a plug-in storage device for SIMATIC S5 programmable logic controller (PLC) CPUs equipped with a dedicated 376 memory slot. It utilizes CMOS EPROM technology to provide 32 KBytes of non-volatile program and data storage, making it the definitive solution for permanently retaining user programs without reliance on backup batteries.
As a member of Siemens’ 376 memory submodule family, the Siemens 6ES5376-1AA21 slots directly into compatible S5-115U, S5-135U, and S5-155U CPUs, delivering rock-solid program retention that survives power loss, battery failure, and decades of industrial service. Its 0.07 kg lightweight, compact form factor and 85389091 commodity classification mark it as a purpose-built industrial component trusted across steel, chemical, power generation, and manufacturing sectors where program integrity is non-negotiable.
Application Scenarios
A steel rolling mill operating a SIMATIC S5-155U-based drive control system faced recurring nightmare scenarios: lithium backup batteries mounted on the CPU were reaching end-of-life, and two separate battery leakage incidents had already corroded PCB traces and caused irreversible program loss. Each incident meant 8–12 hours of emergency recovery, manual reload from paper listings, and production losses exceeding $50,000 per event. By standardizing on the Siemens 6ES5376-1AA21 CMOS EPROM submodule, the plant’s maintenance team eliminated battery dependency entirely. Programs were burned once into the EPROM via a PG programming device and then remained permanently stored—immune to battery failure, immune to power interruption, and immune to the corrosive leakage that had plagued their previous RAM-based configuration. Over 36 months of continuous operation, the Siemens 6ES5376-1AA21 modules have delivered 100% program retention with zero data loss incidents.
In a parallel case, a regional water treatment facility running S5-115U CPUs under CPU 928 needed to expand user memory beyond the onboard 16 kWords limit. The Siemens 6ES5376-1AA21 provided the required 16 kWords (32 KBytes) of external memory expansion, enabling the plant to add advanced PID control loops, expanded alarm logging, and enhanced HMI communication—all while staying on the proven S5 platform. The facility avoided an estimated $120,000 S7 migration cost and 3-week downtime, instead completing the upgrade in under 4 hours per PLC by simply inserting the Siemens 6ES5376-1AA21 into the CPU’s memory slot and downloading the expanded STEP 5 program.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | Siemens 6ES5376-1AA21 |
| Manufacturer | Siemens AG |
| Product Category | Memory Submodule (376 Series) |
| Memory Technology | CMOS EPROM (Erasable Programmable Read-Only Memory) |
| Storage Capacity | 32 KBytes (equivalent to 16 kWords for S5-115U CPU 928 expansion) |
| Data Retention | Non-volatile, permanent – no battery required |
| Erase Method | UV (Ultraviolet) light exposure through quartz window |
| Reprogramming Cycles | 100–1,000 cycles (depending on chip process) |
| Compatible Systems | SIMATIC S5 CPUs with 376 memory submodule slot – S5-115U (CPU 928-3Ux1x), S5-135U, S5-155U |
| Slot Type | 376 memory submodule socket on the CPU module |
| Supply Voltage | 5V DC (drawn via CPU backplane) |
| Weight | 0.07 kg |
| Commodity Code (HS) | 85389091 |
| Operating Temperature | 0°C to +60°C |
| Window Type | Quartz glass window for UV erasure |
| Mounting | Direct plug-in to S5 CPU memory slot |
| Condition Available | New / Refurbished / Repair service |
| Warranty | Up to 24 months |
