CTI 901C Series Modules | 901C-2599 Output Module

Technical Dossier

Product Details And Specifications

CTI 901C Series: Comprehensive Module Range and Technical Overview

The CTI (Control Technology Inc.) 901C series represents a family of I/O and control modules engineered for compatibility with Siemens SIMATIC 505 (formerly Texas Instruments TI 505) programmable logic controller platforms. These modules are deployed across heavy industrial sectors including petrochemical refining, power generation, pulp and paper manufacturing, and water treatment infrastructure. The 901C series was designed as a direct functional and form-factor replacement for legacy TI 505 I/O modules, enabling facilities to extend the operational life of installed SIMATIC 505 systems without full platform migration. Installed base penetration remains significant in North American process industries, where the cost and risk of full DCS/PLC replacement justify long-term spare parts procurement strategies.

The Evolution of 901C Architecture

The 901C series emerged as the SIMATIC 505 platform transitioned from Texas Instruments to Siemens ownership in the 1990s. CTI developed the 901C line to address the growing aftermarket demand for compatible I/O modules as original Siemens production of certain 505-series cards was reduced or discontinued. Architecturally, 901C modules use the same backplane bus protocol as the TI 505 and Siemens SIMATIC 505 racks, ensuring transparent interoperability without firmware modification. Early 901C variants focused on discrete I/O replacement; subsequent generations expanded into analog I/O, specialty function modules, and communication adapters. As the SIMATIC 505 platform has entered end-of-life status with Siemens, the 901C series has become the primary supply channel for facilities requiring certified replacement modules. Compatibility spans SIMATIC 505 racks including the 505-6870, 505-6871, and CTI 2500 series controllers.

901C Full Catalog & Functionalities (SKU List)

Discrete Output Modules

• 901C-2599: 16-point 120VAC discrete output module, SIMATIC 505 rack-compatible, isolated outputs
• 901C-2400: 32-point 24VDC discrete output module, sourcing type, high-density I/O
• 901C-2401: 32-point 24VDC discrete output module, sinking type, field-side isolated
• 901C-2500: 16-point 120VAC output module, triac-based solid-state switching
• 901C-2501: 16-point 240VAC output module, high-voltage process applications
• 901C-2600: 8-point relay output module, dry contact, 2A per point

Discrete Input Modules

• 901C-1200: 32-point 24VDC discrete input module, sourcing, high-density rack mount
• 901C-1201: 32-point 24VDC discrete input module, sinking configuration
• 901C-1300: 16-point 120VAC discrete input module, optically isolated
• 901C-1301: 16-point 240VAC discrete input module, high-voltage field wiring
• 901C-1400: 16-point TTL/5VDC discrete input module, logic-level signals

Analog I/O Modules

• 901C-3400: 8-channel analog input module, 4–20mA / 0–10V selectable, 12-bit resolution
• 901C-3401: 16-channel analog input module, differential inputs, process instrumentation
• 901C-3600: 4-channel analog output module, 4–20mA, 12-bit DAC, loop-powered
• 901C-3601: 8-channel analog output module, 0–10V / 4–20mA, dual-range

Specialty & Communication Modules

• 901C-4800: High-speed counter module, 4-channel, quadrature encoder input support
• 901C-5000: PROFIBUS-DP communication adapter, slave mode, 12Mbps

Sourcing Hard-to-Find & Obsolete 901C Parts

As Siemens has formally discontinued the SIMATIC 505 product line, procurement of 901C series modules through standard distribution channels has become increasingly constrained. DriveKNMS maintains a dedicated inventory of both new-surplus and fully tested refurbished 901C modules to support facilities operating legacy 505 installations. Our sourcing network covers North American, European, and Asia-Pacific industrial surplus markets. For discontinued variants where new-surplus stock is exhausted, DriveKNMS offers board-level repair and functional restoration services with post-repair burn-in testing. All sourced units are cross-referenced against CTI's published compatibility matrices to confirm rack and firmware version alignment prior to shipment. Lead times for common variants such as the 901C-2599, 901C-1300, and 901C-3400 are typically 3–10 business days from confirmed order.

Quality Control for the 901C Range

CTI 901C modules incorporate a passive backplane bus interface that requires verification of both electrical continuity and protocol handshake integrity before deployment. DriveKNMS applies the following test protocol to all 901C units processed through our facility: (1) Visual inspection of PCB, connector pins, and conformal coating for corrosion or mechanical damage. (2) Powered bench test using a SIMATIC 505-compatible rack and controller to confirm module recognition and I/O point addressability. (3) For output modules including the 901C-2599, each output channel is individually exercised under rated load to verify switching response and isolation integrity. (4) For analog modules, calibration verification is performed against NIST-traceable reference instruments to confirm accuracy within published specifications. (5) Final functional test log is retained and available upon request with each unit shipped.