6ES5944-7UB21 - SIMATIC S5 CPU 944B central processing unit

SIMATIC S5 CPU 944B central processing unit that executes the S5 user program and exchanges process data through its documented interfaces.

Documented system function

Rebuilt from individual evidence

System position

Documented characteristics

The source identifies this exact reference as a SIMATIC S5 CPU 944B central processing unit for the S5-115U PLC.

In the documented system, it processes the S5 user program and exchanges process data through its documented interfaces.

The source documents 96 KB of RAM and two interfaces.

Inferred system position: between the S5-115U backplane and the program and process interfaces.

Exact reference: 6ES5944-7UB21
Category: PLC / CPU
Evidence checked: 2026-09-12

System role

This section explains what the product does and where it acts in the surrounding system.

Function: processes the S5 user program and exchanges process data through its documented interfaces.
System position: Sits between the S5-115U backplane and the program and process interfaces.
Upstream / inputs: The S5 rack and connected process interfaces provide the upstream signals.
Downstream / outputs: The CPU presents processed control states to the S5 system.
Limitations: Unknown: the installed system configuration, wiring, firmware state, physical condition and replacement compatibility.

Evidence ledger

Facts, inferences, and unknowns are kept separate.

Facts

The cited source identifies 6ES5944-7UB21 as a SIMATIC S5 CPU 944B central processing unit for the S5-115U PLC.
Confidence: high
- sps-service.eu — retrieved 2026-09-12; high confidence
- www.plc2day.com — retrieved 2026-09-12; high confidence
The cited source describes 6ES5944-7UB21 as executing the S5 user program and exchanges process data through its documented interfaces.
Confidence: high
- sps-service.eu — retrieved 2026-09-12; high confidence
- www.plc2day.com — retrieved 2026-09-12; high confidence
The cited source documents 96 KB of RAM and two interfaces.
Confidence: high
- sps-service.eu — retrieved 2026-09-12; high confidence
- www.plc2day.com — retrieved 2026-09-12; high confidence

Inferences

Inferred system position: between the S5-115U backplane and the program and process interfaces.
Confidence: medium
Rationale: The exact-reference identity and documented function establish where this component participates in the described control path.
- sps-service.eu — retrieved 2026-09-12; high confidence
- www.plc2day.com — retrieved 2026-09-12; high confidence

Unknowns

Unknown: the installed system configuration, wiring, firmware state, physical condition and replacement compatibility.
Confidence: low
Missing evidence: The individual web sources describe the product but do not establish a particular installation or unit condition.

System position diagram

The upstream system stage connects through the exact product to the downstream system stage. — The exact product participates in the system path described by the cited evidence.

View Mermaid source

flowchart LR; Upstream --> Component; Component --> Downstream

View diagram labels

Nodes: Upstream system stage; Exact product; Downstream system stage
Edges: Documented input or supply path; Documented output or control path

Next action

The captured evidence supports the documented identity and system role of 6ES5944-7UB21.

Unknown: confirm the installed rack, wiring, firmware, unit condition and replacement compatibility before use.

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