Honeywell DL2-700 Series Modules – DL2-742-0001

Technical Dossier

Product Details And Specifications

Honeywell DL2-700 Series Technical Notes

The Honeywell DL2-700 series represents a core I/O module family deployed within Honeywell's TDC 3000 and PlantScape distributed control system (DCS) architectures. These modules have accumulated decades of installed base across global heavy industry sectors including petroleum refining, chemical processing, nuclear power generation, pulp and paper manufacturing, and offshore platform automation. The DL2-700 series provides the physical interface layer between field instrumentation and the DCS controller network, handling analog signal conditioning, digital state acquisition, and process output commands. Due to the long operational lifecycles typical of DCS installations—often 20 to 30 years—DL2-700 modules remain in active service at facilities worldwide, creating sustained demand for both operational spares and lifecycle replacement units.

The Evolution of DL2-700 Architecture

The DL2-700 module family was introduced as part of Honeywell's Data Hiway-based control infrastructure, designed to operate within the Local Control Network (LCN) and Basic Controller (BC) environments of the TDC 3000 platform. Early-generation modules in this series used parallel backplane communication with fixed-address slot assignment, requiring precise physical placement within the DL2-700 chassis. As the TDC 3000 platform matured through the 1990s and into the 2000s, Honeywell introduced firmware revisions that extended compatibility with the Universal Control Network (UCN) and Application Module (AM) layers, allowing DL2-700 I/O to interface with higher-level supervisory functions without hardware replacement.

The transition from TDC 3000 to Experion PKS introduced a compatibility boundary: DL2-700 modules can be retained in hybrid configurations using Honeywell's Series C I/O migration path, but direct plug-in compatibility with Experion C300 controllers requires the use of CIOM-A or LLMUX adapter hardware. Facilities that have not yet migrated to Experion PKS continue to operate DL2-700 modules as primary I/O, making long-term spare parts availability a critical operational requirement. The DL2-742-0001 specifically functions as an analog input module, accepting 4–20 mA or 1–5 V field signals and converting them to digital process variable representations for the DCS controller.

DL2-700 Full Catalog & Functionalities (SKU List)

Analog Input Modules (AI)

• DL2-742-0001: 8-channel analog input module, 4–20 mA / 1–5 V, for TDC 3000 DL2-700 chassis
• DL2-742-0002: 8-channel analog input module, thermocouple/RTD input variant, multi-type sensor support
• DL2-742-0003: 16-channel analog input module, high-density AI for expanded field point count
• DL2-742-0004: 8-channel analog input, HART-enabled, supports field device diagnostics over 4–20 mA loop
• DL2-742-0005: Analog input module with galvanic isolation per channel, for high-noise environments

Analog Output Modules (AO)

• DL2-743-0001: 8-channel analog output module, 4–20 mA, for final control element command signals
• DL2-743-0002: 8-channel analog output, HART pass-through, supports smart valve positioner communication
• DL2-743-0003: 4-channel high-current analog output module, for high-load actuator applications

Digital Input Modules (DI)

• DL2-741-0001: 16-channel digital input module, 24 VDC, dry contact and wet contact compatible
• DL2-741-0002: 32-channel digital input module, high-density DI for status and alarm monitoring
• DL2-741-0003: 16-channel digital input, 120 VAC field voltage, for legacy field wiring compatibility
• DL2-741-0004: 16-channel digital input with SOE (Sequence of Events) timestamping, 1 ms resolution

Digital Output Modules (DO)

• DL2-744-0001: 16-channel digital output module, 24 VDC sourcing, for solenoid and relay control
• DL2-744-0002: 8-channel relay output module, SPDT contacts, 5 A rated, for motor starter applications
• DL2-744-0003: 16-channel digital output, 120 VAC, for legacy actuator and indicator circuits

Power Supply & Chassis

• DL2-700-CHASS: DL2-700 series base chassis, 8-slot or 16-slot configuration, backplane bus assembly
• DL2-700-PSU: Redundant power supply module for DL2-700 chassis, 24 VDC regulated output