Siemens 6ES5342-3AA11 SIMATIC S5 342 Parity Check Module

Features

-Main-memory parity supervision
-External-memory monitoring
-One or two parity bits per word
-Fault-address register
-Red parity-error indicator
-200 ns CPU error signal

Product Overview

The Siemens 6ES5342-3AA11 is a SIMATIC S5 Series 342 parity check module to monitor memory integrity in an S5-150S control system. Depending on its configuration and slot identification, it can supervise either the controller’s main memory or external memory built with SIMATIC S5 340 and 350 memory modules. During a memory write cycle, the module generates parity information and stores it in buffered RAM. During a read cycle, the stored parity values are compared with newly generated values. If they do not match, the module records the affected address, activates its red parity-error LED and sends a 200 ns error signal to the CPU.

Technical Specifications

Benefits

-Detects inconsistencies in monitored memory data
-Identifies the address associated with a parity fault
-Provides immediate visual fault indication
-Supports main-memory and external-memory configurations
-Assists systematic controller troubleshooting
-Preserves the original SIMATIC S5 monitoring architecture

Application Areas
S5-150S Main-Memory Monitoring--The 6ES5342-3AA11 can supervise selected areas of the S5-150S main memory. It compares the parity information generated during read operations with the values previously stored during write operations.

Memory-Fault Diagnostics--When a parity mismatch occurs, the module stores the affected address in a readable register and illuminates the front-panel LED. This information helps engineers distinguish a memory-integrity problem from an unrelated CPU, power or program fault.

Controller Commissioning--The module is applicable during commissioning or recommissioning of an S5 memory system. Parity values must be generated before normal supervision begins, particularly after the module has been removed, reinstalled or its buffered data has been lost.

Frequently Asked Questions

1. Does the 6ES5342-3AA11 add program memory to the controller?
No. It is a parity-checking module rather than a user-program storage module. The 340 and 350 modules provide the monitored memory, while the 342 module generates, stores and compares the associated parity information.

2. What happens when the module detects a parity error?
The address associated with the incorrect data is transferred to a readable error-address register. The red parity-error LED is activated, and a 200 ns signal is sent to the CPU.

3. Why is parity generation required during commissioning?
The module needs valid reference parity values before it can compare later read operations. Removing the module interrupts its buffered supply and can erase the parity information stored in its internal RAM. A new parity-generation cycle is therefore required before normal monitoring resumes.