Siemens 6DD1607-0AA2 UPS for Simatic S7-400

The Siemens 6DD1607-0AA2 is a UPS (uninterruptible power supply) module designed specifically for the SIMATIC S7-400 programmable logic controller. It ensures that the PLC and connected I/O modules receive stable 24 V DC power during brownouts or complete mains failure by switching to an external battery. The module mounts on the S7-400 I/O rack and communicates the battery status to the CPU.

Electrical Specifications

Input voltage: 24 V DC nominal (20.4-28.8 V). Output voltage: 24 V DC (buffered, same as input). Output current: 10 A continuous (15 A peak for 1 second). The module is designed for use with external lead-acid or VRLA batteries (12 V or 24 V, user-provided). Charging current: 1 A (temperature compensated). Buffering time depends on battery capacity; typical with 12 Ah battery provides 30 minutes at 5 A. Efficiency: >90% when on mains.

Communication and Diagnostics

The UPS communicates with the S7-400 CPU via an internal backplane bus (no extra wiring). The CPU can read battery charge level, remaining runtime, and fault status (e.g., battery low, overload, charger fault). A software function block (FB UPS) is provided in the SIMATIC STEP 7 library to trigger orderly program shutdown when battery is low. LEDs on the front panel: green (mains OK), yellow (battery mode), red (fault).

Mechanical and Environmental

Dimensions: 125 mm x 125 mm x 120 mm (single slot width). Weight: 0.6 kg. Protection rating: IP20. Operating temperature: 0°C to 60°C. Storage: -40°C to 85°C. Humidity: 5% to 95% (non-condensing). The module has screw terminals for battery connection (two terminals: +BAT and -BAT). An external 5 A fuse must be installed in series with the battery. The module also includes a 24 V DC output terminal to power the PLC rack.

Installation and Configuration

Insert the module into any free slot of the S7-400 rack (except the CPU slot). Connect the external battery (observe polarity). In STEP 7 hardware configuration, assign the module’s start address and enable cyclic diagnostics. The UPS status is stored in the process image input table. The module automatically performs a battery test every 7 days (brief load test). Battery replacement alarm can be configured to send an email or SMS via the CPU’s communication processor.

Applications

Used in critical processes such as chemical plants, power generation, water treatment, and data centers where loss of PLC power could cause unsafe conditions or data loss. The 6DD1607-0AA2 allows the CPU to complete a controlled shutdown and save retentive data to the memory card.