Siemens 6ES5944-7UA21 Central Processing Unit

This processor handles complex automation tasks for large-scale industrial applications. The Siemens 6ES5944-7UA21 executes user logic and manages high-speed I/O communication efficiently. It measures 232 mm in width and 75 mm in height. This unit weighs approximately 1.1 kg for secure rack installation.

Technical Specifications Table

Parameter	Value
Product Model	Siemens 6ES5944-7UA21
Category	Central Processing Unit (CPU)
Compatible Racks	SIMATIC S5-135U, 155U
User Memory	48 KB RAM (battery-backed)
Memory Technology	Static RAM with lithium battery
Processing Speed	1 ms per 1K of bit operations
I/O Address Space	2048 digital inputs + 2048 digital outputs
Timer/Counter Range	256 timers, 256 counters
Dimensions (W x H x D)	232 mm x 75 mm x 130 mm
Weight	1.1 kg
Front Interface	1 x 20-pin female connector
Programming Port	1 x 15-pin SUB-D (RS232/RS422/TTY)
Internal Components	1 x 16-bit microprocessor, 1 x quartz oscillator
Energy Storage	1 x 3.6 V lithium battery (1 Ah capacity)
Battery Life	Approximately 2 years
Operating Temperature	0°C to 60°C

Internal Architecture and Processing Power

This CPU contains a high-performance 16-bit microprocessor running at 10 MHz. A quartz oscillator provides precise timing for all logic operations. The Siemens 6ES5944-7UA21 stores user programs in 48 KB of static RAM. A replaceable 3.6 V lithium battery maintains this memory during power outages. The processor executes bit operations in approximately 1 millisecond per kilobyte. Consequently, this unit handles complex tasks like closed-loop control and fast data logging.

Installation and Programming Guide

First, insert this CPU into the designated slot of your 135U or 155U rack. Next, connect your programming device to the 15-pin SUB-D port. Then, upload your STEP 5 program using an appropriate cable and software. The module supports all standard STEP 5 operations including advanced math functions. You can expand I/O by adding up to 4 extension racks. This CPU communicates with remote I/O via the built-in interface. Always replace the lithium battery when the low voltage indicator lights up. Remove the module from the rack before changing the battery for safety.