Siemens 6ES5188-3UA21 Central Unit

The 6ES5188-3UA21 serves as the CPU for SIMATIC S5-115U systems. This module executes user logic and manages all I/O operations. It supports up to 16KB of user program memory.

Key Technical Specifications

Parameter	Value
Processor	16-bit proprietary ASIC
Program Memory	16 KB RAM (battery-backed)
Execution Speed	1.5 ms per 1K instructions
Data Memory	1 KB flags + 64 timers/counters
Supply Voltage	24V DC ±20%
Power Consumption	14 W typical
Digital I/O Capacity	1024 channels max
Analog I/O Capacity	64 channels max
Communication Ports	2 x TTY (20 mA)
Board Dimensions	25.0 cm x 18.0 cm x 4.0 cm
Weight	0.62 kg (1.37 lbs)
Component Count	158 discrete components
Energy Storage	3300 µF bulk capacitance
Operating Temperature	0°C to 60°C

Physical Dimensions and Component Layout

This module measures 25.0 cm in length and 18.0 cm in width. Its total height reaches 4.0 cm including the heat sink. 6ES5188-3UA21 weighs 0.62 kg for stable rack mounting. You will find 158 discrete components on a six-layer PCB.

Moreover, the module integrates a 3300 µF bulk capacitor bank. This bank stores energy for short power interruptions. It also filters noise from the 24V DC supply rail.

Processing Performance and Memory

The 16-bit ASIC processor executes 1K instructions in just 1.5 ms. This speed supports fast scan cycles for real-time control. The 16KB RAM stores ladder logic and statement list programs. A lithium battery retains this memory for up to 300 days without power.

Communication and Expansion

Two built-in TTY interfaces connect to programming devices or operator panels. Each port uses a 20 mA current loop for reliable long-distance communication. You can expand I/O using up to 8 external expansion racks. The module also supports up to 64 analog channels.

Typical Application Scenarios

You can deploy 6ES5188-3UA21 in SIMATIC S5-115U systems for mid-sized automation tasks. It also works well for batch processing, material handling, and machine tool control. This CPU handles sequential control, PID loops, and data logging. Its 16KB memory suits applications with up to 400 I/O points.