SIEMENS 6ES5946-3UA23

Siemens SIMATIC S5 CPU 946 Module

Description

The 6ES5946-3UA23 is a Central Processing Unit (CPU) from the well-regarded Siemens SIMATIC S5 series. Specifically designed for the S5-135U and S5-155U PLC systems, this CPU 946 is a powerful and reliable core for complex automation tasks. It is an essential component for maintaining and extending the life of legacy S5-based machinery.

Specifications

• Manufacturer: Siemens
• Series: SIMATIC S5
• Product Type: Central Processing Unit (CPU 946)
• For use with: S5-135U / S5-155U Systems
• Memory: 384 Kbytes RAM
• Programming: Requires STEP 5 software

Label Info

• Model: 6ES5946-3UA23
• E-Stand (Version): 02

Application

This CPU is ideal for controlling industrial processes in manufacturing, logistics, and process control where SIMATIC S5 systems are still in operation. It provides a direct replacement part to minimize downtime and avoid costly system-wide upgrades.

Country of Origin

Made in Germany.

CO2 Impact

By purchasing this pre-owned module, you are helping to avoid the emission of approximately 60 kg of CO2, which would be generated in the production of a new replacement. This is a sustainable choice for your operations.

Availability

This item is an obsolete spare part but is available from our stock. Order now from spareparts2day for expert support and fast delivery.

FAQ

Can I replace a different S5-135U CPU, like a CPU 945, directly with this CPU 946?

While both are for the S5-135U/155U system, a direct swap is not always possible without program modification. The CPU 946 (6ES5946-3UA23) has a different instruction set and memory capacity (384KB) compared to other S5 CPUs. Always check your program’s hardware configuration and system block requirements in STEP 5 before attempting a replacement.

What is the required programming software and cable for this CPU?

This CPU is programmed using Siemens STEP 5 software. A standard TTY (20mA) current loop interface is required for connection, often via a converter like the 6ES5734-1BD20 to a PG (Programming Device) serial port. Modern USB-to-S5 adapters are also available from third-party suppliers.

Does this CPU module require an external memory module (EPROM/EEPROM) to store the program permanently?

Yes, for non-volatile program storage, this CPU requires a separate memory sub-module (EPROM or EEPROM) to be plugged into the mainboard. The internal RAM is volatile and will lose its contents upon power loss if not backed up by a battery. The memory sub-module ensures the program is retained.

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Last Update: Friday, March 13, 2026