Siemens 6ES5252-5AA11 – Synchronizing Module for SIMATIC S5 Systems

The Siemens 6ES5252-5AA11 synchronizes multiple S5 central processing units in redundant configurations. This basic module measures 250 mm in depth and 25 mm in width. It fits standard SIMATIC S5 rack slots without any modifications. The unit weighs 0.44 kg, making installation quick and straightforward.

Synchronization Function and Communication

This synchronizing module keeps two S5 CPUs running identical program scans simultaneously. The Siemens 6ES5252-5AA11 exchanges status data between master and backup processors every millisecond. It detects when the primary CPU fails and triggers an automatic switchover. The module compares critical data words to ensure both processors remain synchronized. It also monitors timing differences between the two connected CPUs.

Internal Architecture and Component Layout

The module contains two separate circuit boards inside its plastic housing. One board handles data comparison, while the other manages switchover logic. The Siemens 6ES5252-5AA11 includes a dedicated comparator circuit for data validation. A 14-pin ribbon cable connects paired modules across adjacent rack slots. The module stores 56 µF of capacitance for power supply filtering only.

Interface Connections and Status Indicators

You will find one 20-pin connector on the front panel for inter-CPU communication. The Siemens 6ES5252-5AA11 provides LED indicators for master, backup, and fault status. Six diagnostic LEDs help troubleshoot synchronization and handshake issues quickly. The module outputs a relay contact signal when a switchover event occurs. It also generates a system alarm when communication between CPUs fails.

Power Requirements and Environmental Tolerance

The Siemens 6ES5252-5AA11 draws 80 mA at 5V DC from the backplane supply. It requires no external 24V DC power for its internal circuits. The module operates reliably from 0°C to 60°C ambient temperature. It tolerates humidity levels up to 95 percent without any condensation issues. The unit withstands vibration up to 2g from 10 to 500 Hz.

Below is a complete summary of its technical specifications.

The Siemens 6ES5252-5AA11 replaces older synchronizing modules in redundant S5 configurations. You need two modules and one ribbon cable for a complete redundant pair. This module also supports hot-swapping, so you can replace it without powering down. Consequently, it provides fault-tolerant control for critical processes like power plants.