QLSDM024DCCBN – Siemens QUADLOG Standard Discrete Module (SDM+) 24 VDC

Overview

The Siemens QLSDM024DCCBN is the Standard Discrete Module (SDM+) used in Siemens APACS+ and QUADLOG control and safety systems, originally developed by Moore Products Co. before the platform moved to Siemens. It is the general-purpose discrete I/O card of the QUADLOG family, handling on/off field signals such as limit switches, pushbuttons, pressure and level switches, contactor feedback and solenoid or relay commands. The “024DC” in the order code identifies the 24 VDC version of the module, which is the standard field voltage for QUADLOG discrete I/O. The module carries Moore/Siemens assembly number 16101-211/1 on its label.

APACS+ and QUADLOG were placed into cancellation by Siemens in October 2011 and moved to “repair parts only” status. Many refineries, gas plants, power stations and chemical units in the Middle East still run these systems, so a reliable source of genuine QLSDM024DCCBN modules is important for keeping installed I/O racks running until a planned migration. Seven Star LLC supplies the Siemens QLSDM024DCCBN as a genuine spare for APACS+/QUADLOG users in Oman and the GCC.

Role of the Siemens QLSDM024DCCBN in a QUADLOG System

A QUADLOG system is built around a Critical Control Module (CCM) that executes the control and safety logic, with I/O modules installed in the same rack and connected through the backplane. Two families of discrete I/O exist. The Critical Discrete Module (CDM, for example QLCDM024DCBAN) is used for safety-rated trip and interlock signals where full diagnostics and fault tolerance are required. The Standard Discrete Module, the QLSDM024DCCBN, is used for the many non-critical discrete points in the same plant: status indications, permissives, alarms, motor run feedback and general on/off outputs.

Using the SDM+ for standard points lets engineers reserve the more expensive critical modules for real safety functions while still keeping all plant signals within one integrated QUADLOG/APACS+ database. Its channels are assigned in the system configuration (the 4-mation engineering environment for APACS+/QUADLOG), so the module fits into the existing application database without changes to the control strategy. The module is typically installed with its matching terminal assembly (field termination) that brings the field wiring into the cabinet.

Key Features

• Genuine Siemens (Moore) APACS+/QUADLOG Standard Discrete Module, SDM+ version.
• 24 VDC discrete I/O, as indicated by the “024DC” code in the part number.
• Channel assignments held in the APACS+/QUADLOG system configuration, so a replacement module picks up the existing application.
• Rack-mounted, backplane-connected module that plugs into existing QUADLOG/APACS+ I/O slots without rewiring the rack.
• Used for non-safety-critical discrete signals alongside CDM modules that handle safety trips.
• Direct like-for-like replacement for a failed QLSDM024DCCBN, so no changes to application logic are needed.

Technical Specifications

Always compare the label on your installed module (part number, assembly number and revision) with the replacement before installation. Where a site has mixed module revisions, Seven Star LLC can match the revision to the one already in service.

Applications

The Siemens QLSDM024DCCBN is found wherever APACS+ or QUADLOG systems are still in operation. Typical uses include:

• Oil & gas production and gas processing – valve limit switches, pump run status, compressor permissives and alarm contacts.
• Refining and petrochemicals – non-critical interlocks and status signals running alongside QUADLOG safety functions on the same controller.
• Power generation – balance-of-plant discrete signals, breaker status and auxiliary equipment commands.
• Water and wastewater – pump and valve control, level switches and panel indications in older APACS+ installations.

Maintaining a Legacy QUADLOG System

Because APACS+ and QUADLOG are no longer in active production, plants depend on spare modules to keep systems available. Good practice is to hold at least one spare QLSDM024DCCBN for every rack type in service, together with spares for the CCM and critical modules. Modules should be stored in ESD-safe packaging in a dry, temperature-controlled store, and spares should be powered up and tested periodically where possible.

When a module is replaced, follow the site’s management-of-change procedure. Even though the SDM+ handles non-safety points, the configuration and channel assignment must match the original so that field devices behave as expected after the swap. Many operators use the spare-parts stage to plan a phased migration to a newer Siemens platform, while keeping the existing system reliable in the meantime.

Why Source the Siemens QLSDM024DCCBN from Seven Star LLC

Seven Star LLC supplies genuine Siemens QLSDM024DCCBN modules to industrial users across Oman and the GCC. Before we quote, we confirm the exact part number, assembly number and revision against your installed module, and we tell you clearly whether the offered unit is new, new-surplus or tested used stock. Modules are shipped in ESD-safe packaging with documentation of condition and testing where available.

We can also help with related APACS+/QUADLOG spares such as critical discrete modules, analog modules, power supplies and terminal assemblies, so your maintenance team can build a complete spares list from one supplier. If you are planning a shutdown or turnaround, share the list of modules early so we can check availability and lead times well before the work window.

Request a Quote for Siemens QLSDM024DCCBN

For availability, condition options and delivery time for the Siemens QLSDM024DCCBN Standard Discrete Module, send us your part number and the label details of your installed module, and our team will prepare a quotation for delivery in Oman and the GCC.

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