Siemens QUADLOG Modules

Technical Dossier

Product Details And Specifications

Siemens QUADLOG Series: Comprehensive Module Range and Technical Overview

The Siemens QUADLOG safety system is a dedicated Safety Instrumented System (SIS) platform engineered for high-demand process industries including petroleum refining, chemical processing, nuclear power generation, and offshore oil & gas production. QUADLOG is designed to meet IEC 61508 SIL 2 and SIL 3 requirements, providing redundant, fault-tolerant control architectures for Emergency Shutdown (ESD), Fire & Gas (F&G), and Burner Management Systems (BMS). Installed across thousands of critical process units globally, the QUADLOG platform remains one of the most widely referenced legacy SIS architectures in long-term plant maintenance inventories.

The Evolution of QUADLOG Architecture

QUADLOG was developed by Moore Products Co., which was subsequently acquired by Siemens. The platform was positioned as a quad-redundant safety controller — its name directly referencing its four-channel voting logic architecture (4oo4D). Early deployments in the 1990s established QUADLOG as a preferred SIS solution for North American and European refineries operating under ISA S84.01 and early IEC 61511 frameworks.

The system architecture is built around a proprietary backplane bus connecting the SAM (Safety Application Module), I/O modules, communication adapters, and power supplies. The SAM module — including the QLSAMBAN — serves as the central logic solver, executing the safety application program and managing inter-module diagnostics. Over successive hardware revisions, Siemens introduced enhanced diagnostic coverage, improved MTBF ratings, and expanded communication protocol support (PROFIBUS, Modbus RTU, OPC).

As the QUADLOG platform has entered its end-of-life and obsolescence phase, Siemens has directed new SIS projects toward the SIMATIC Safety Integrated platform (S7-300F, S7-400F/FH, S7-1500F). However, the installed base of QUADLOG systems in brownfield facilities remains substantial, creating sustained demand for original spare parts, refurbished modules, and lifecycle extension support.

QUADLOG Full Catalog & Functionalities (SKU List)

The following SKUs represent the core QUADLOG module range. All models listed are verified components of the Siemens QUADLOG SIS platform.

Safety Application Modules (SAM / Logic Solvers)

• QLSAMBAN: QUADLOG Safety Application Module, standard BAN variant, central logic solver for SIL 2/3 ESD applications
• QLSAM: QUADLOG Safety Application Module, base version, quad-redundant voting logic processor
• QLSAMR: QUADLOG SAM replacement/repair revision, compatible with standard QUADLOG backplane

Digital Input Modules (DI)

• QLDIB16: QUADLOG 16-channel 24 VDC digital input module, SIL 2 rated, field device monitoring
• QLDIB32: QUADLOG 32-channel digital input module, high-density field wiring, process shutdown inputs
• QLDI24V: QUADLOG digital input, 24 VDC, single-ended, for discrete sensor interfacing

Digital Output Modules (DO)

• QLDOB16: QUADLOG 16-channel digital output module, relay-driven, ESD valve and actuator control
• QLDOB8R: QUADLOG 8-channel relay output module, high-current switching for solenoid valves

Analog Input Modules (AI)

• QLAIB8: QUADLOG 8-channel analog input, 4–20 mA HART-compatible, transmitter signal acquisition
• QLAIB16: QUADLOG 16-channel analog input module, process variable monitoring for SIS loops

Analog Output Modules (AO)

• QLAOB4: QUADLOG 4-channel analog output, 4–20 mA, positioner and control element interface

Power Supply Modules (PS)

• QLPS24: QUADLOG 24 VDC redundant power supply module, backplane bus power distribution
• QLPSR: QUADLOG power supply redundancy module, hot-swap capable, no-break switchover

Communication & Network Modules

• QLCOMB: QUADLOG communication bridge module, Modbus RTU master/slave interface to DCS/SCADA
• QLPROFIB: QUADLOG PROFIBUS DP adapter, integration with Siemens SIMATIC DCS environments
• QLENET: QUADLOG Ethernet communication module, OPC server connectivity for historian integration

Chassis & Backplane

• QLCHAS8: QUADLOG 8-slot chassis, standard rack for SAM and I/O module mounting
• QLCHAS16: QUADLOG 16-slot expanded chassis, high I/O count process unit configurations

Sourcing Hard-to-Find & Obsolete QUADLOG Parts

With Siemens having discontinued active production of QUADLOG hardware, procurement of modules such as the QLSAMBAN and associated I/O cards requires sourcing from specialist industrial spare parts distributors. DriveKNMS maintains a dedicated inventory of QUADLOG modules sourced from decommissioned plant assets, authorized surplus channels, and verified refurbishment programs.

DriveKNMS provides lifecycle extension support for QUADLOG installations including: original replacement modules with full traceability documentation, functional testing against QUADLOG backplane communication protocols, and cross-reference advisory for migration to Siemens SIMATIC Safety Integrated where plant schedules permit. All QUADLOG modules are shipped with inspection reports and are available for emergency same-day dispatch to minimize process downtime.

Quality Control for the QUADLOG Range

QUADLOG modules present specific testing challenges due to their proprietary quad-redundant backplane bus architecture and internal voting logic. DriveKNMS applies the following QC procedures to all QUADLOG inventory:

• Backplane bus continuity and signal integrity verification using QUADLOG-compatible test chassis
• SAM module logic solver functional test: application program load, watchdog timer validation, and diagnostic self-test cycle completion
• I/O module channel-by-channel verification: input threshold accuracy (±0.1% FS for analog), output switching confirmation for relay and solid-state channels
• Communication module protocol handshake testing: Modbus RTU frame integrity, PROFIBUS DP token ring participation
• Visual inspection: capacitor condition, connector pin integrity, conformal coating assessment, firmware revision labeling
• Burn-in cycle: 48-hour powered operation under simulated load prior to shipment

For QUADLOG module availability, cross-reference support, or emergency spare parts procurement:

• Email: [email protected]
• WhatsApp: +86 18359293191
• Web: driveknms.com