Allen-Bradley 1746-OG16 5V TTL Output Module for SLC500 Systems: Available Now, Perfectly Connected to Low-Speed Digital Displays and Logic Chips
2026-06-26

I. Introduction

In aging production line upgrades, small-scale automation equipment, testing equipment, and semiconductor-related industrial control scenarios, a large number of devices utilize Rockwell Allen-Bradley SLC 500 series PLCs. Although this platform is in its mature lifecycle, a large number of existing devices are still operating stably, leading to a continuous increase in demand for and replacement of dedicated I/O modules. Among them, the 1746-OG16, as the only 16-channel 5V sinking current-type TTL digital output module in the SLC500 system, is specifically designed to adapt to 5V low-voltage loads such as TTL logic chips, monochrome/dual-color digital displays, and low-speed pulse acquisition boards. Unlike 24V DC output modules, it fills the hardware gap for 5V level signal output in industrial control.

This product originates from Rockwell's original specification manual 1746-RM003 and discrete I/O product manual. It adopts a standard single-slot rack structure, incorporates opto-isolation circuitry, and features built-in surge suppression design. Its compatibility and stability meet Class I Division 2 explosion-proof requirements. Currently, we maintain a stock of brand-new original equipment parts, providing a stable supply solution for equipment maintenance, production line upgrades, and complete system integration, addressing the market's pain points of scarce TTL dedicated output modules and difficulty in selecting alternatives.

II. Core Product Positioning and Unique Advantages

Dedicated TTL Sinking Current Output Design, 5V Low-Voltage Dedicated

Most SLC500 digital output modules on the market are 24V transistor or relay models. Only the 1746-OG16 supports 4.5~5.5V standard TTL levels, employing low-level conduction logic (low level = output conduction). The maximum sinking current per channel is 24mA, making it compatible with various microcontrollers, counters, digital tubes, industrial control data acquisition cards, and other 5V low-voltage loads. This avoids the problem of 24V modules burning out TTL chips. The module has built-in opto-isolation, and the backplane circuitry is electrically isolated from the field 5V load, preventing PLC controller failures caused by high and low voltage crosstalk.

High-density single-slot 16-channel layout

A single 1746 rack slot integrates 16 independent outputs, eliminating the need for multiple module stacking and significantly saving control cabinet installation space. Suitable for equipment with compact I/O points, such as testing equipment, small packaging machines, and laboratory automation equipment. Each module features independent channel LED status indicators for rapid single-channel fault location, reducing downtime for troubleshooting.

Comprehensive anti-interference and protection configuration

The module incorporates native surge suppression circuitry to suppress voltage spikes caused by load switching. For external inductive TTL loads such as relays and small coils, additional parallel absorption diodes can be connected to further extend their lifespan. The backplane power supply design eliminates the need for an external independent 5V power supply, directly powered by the SLC rack power supply, simplifying cabinet wiring and reducing redundant power cables.

The entire SLC500 controller series is compatible. It perfectly matches the entire 1747-L511/514/524/531/532/533/541/542/543/551/552/553 CPU series. The RSLogix 500 software requires no special configuration, directly recognizing the module address without additional program conversion. For upgrading older SLC production lines, no controller replacement is needed; only the I/O modules need to be replaced to achieve 5V signal expansion.

III. Mainstream Application Scenarios

Semiconductor Testing Equipment: Drives 5V digital display panels, TTL communication daughterboards, and low-speed indicator lights on sorting machines, accurately outputting logic level signals to ensure stable chip testing data output.
Small Packaging and Assembly Equipment: The equipment incorporates counters, indicator screens, and miniature 5V solenoid valve drivers, adapting to low-power TTL actuators and suitable for precision small-scale workstation control.
Laboratory Automation and Testing Fixtures: Various aging test benches and signal acquisition fixtures, outputting 5V trigger pulses, and interfacing with data acquisition cards and host computer I/O boards.
Existing SLC500 Production Line Upgrades: Aging replacement of existing equipment's TTL displays and logic control modules, without replacing the entire PLC system, reducing upgrade costs and downtime.
Small Building Measurement and Control Equipment: Low-voltage signal indication and local data display output, compatible with low-power 5V field indication devices.

IV. Hardware Architecture and Power Supply Logic

1. Rack Power Supply Rules

The 1746-OG16 relies entirely on the SLC 500 rack backplane for power. The backplane's 5V operating current is 180mA, and the maximum total output current of the entire unit is 0.384A. 1. **Backplane Current of All I/O Modules within the Rack:** The backplane current of all I/O modules must be calculated cumulatively to prevent rack power supply overload. Before selection, the total 5V power consumption of all modules must be calculated to match a 1746 kW rack power supply.

2. Output Electrical Logic

The module is a current-sinking TTL output: the positive terminal of the external 5V load is connected to +5V, and the negative terminal is connected to the module's output terminal. The channel is on at low levels (0.2~0.8V) and off at high levels (2~5.5V). A NOT instruction is required in the program to complete the conventional high-level logic conversion.

3. Isolation and Safety Design

Opto-isolation components are installed between the channel and the backplane. The isolation withstand voltage meets industrial standards, preventing reverse intrusion of 5V load interference into the PLC main control. The module complies with UL, CSA, and Class I Division 2 explosion-proof certifications, making it safe for use in dusty and oily/gasy environments. The casing has flame-retardant properties.

V. Detailed Technical Specifications

Brand & Manufacturer: Rockwell Allen-Bradley

Part Number: 1746-OG16

Product Series: SLC 500 Discrete Digital Output Module

Output Type: 16-Channel 5V DC Current Sinking TTL Output

Operating Voltage: 4.5~5.5V DC TTL Level

Rated Current per Channel: 24mA per point

Maximum Total Module Output Current: 0.384A

Backplane 5V Current Draw: 180mA

ON Voltage Level: -0.2~0.8V DC (Low Level Active)

OFF Voltage Level: 2.0~5.5V DC

Step Response: 60ms Turn-On, 2.5ms Turn-Off

Isolation: Optical Isolation (Between Backplane and Field Loads)

Compatible Chassis: 1746 Series 4/7/10/13 Slot SLC Chassis

Supported Software: All Versions of RSLogix 500

Applicable Loads: TTL Logic Chips, 5V Digital Displays, Low-Power Indicators, Trigger Acquisition Boards

Certifications: UL, CSA, Class I Division 2

Surge Protection: Built-in Surge Suppression, External Diode Allowed for Inductive Loads

VI. Product Supply and Summary

The 1746-OG16, as a rare dedicated TTL output module for the SLC500 platform, addresses the core needs of existing industrial control equipment for 5V low-voltage signal expansion and spare part replacement. Currently, a large number of older SLC devices in the automation maintenance and equipment upgrade market are entering their spare parts replacement cycle. 24V general-purpose I/O cannot adapt to TTL low-voltage loads, making this module an irreplaceable original standard spare part.

Our channels provide a long-term, stable supply of brand-new, original 1746-OG16 modules, providing original manufacturer information, specification manuals, and wiring instructions. We support bulk purchases and single-unit maintenance retail, and can simultaneously supply a one-stop solution for the entire SLC series of CPUs, inputs, analog signals, and relay I/O modules.

For SLC500 upgrades to the CompactLogix/Compact 5000 platform, we can simultaneously provide module replacement solutions, program migration technical support, and hardware migration reference solutions to reduce the technical barriers to production line upgrades and downtime losses.

FAQ (Frequently Asked Questions)

Q1: What are the safety precautions for installing the 1746-OG16?

A: The main power supply to the SLC rack must be disconnected before disassembly, assembly, and wiring. Hot-plugging of modules is strictly prohibited. Use 1746-N2 covers to prevent dust from unused rack slots. It is recommended to connect freewheeling diodes in parallel for all TTL inductive loads (small 5V coils) to reduce surge damage. The rack power supply must be calculated based on the total backplane current of all modules to avoid overload.

Q2: The module output is active low. How does the program handle the normal high-level logic?

A: In the RSLogix 500 ladder diagram, adding a NOT instruction to the corresponding output point will implement the normal control logic for high-level conduction. A standard ladder example is included in the manual.

Q3: How to troubleshoot a single-channel no-output fault in the module?

Check the channel LED indicator. If no light is on, check if the backplane module is securely locked.

Measure the external 5V power supply to ensure it is normal and that the load wiring is not reversed.

Force the program to the corresponding output point and observe the level change to determine whether the problem is with the program logic or hardware.

A short circuit in the load will trigger channel protection. Disconnect the load and test the module terminals separately.

Q4: Can this module directly replace a 24V output module?

A: No, they cannot be directly interchanged. The power supply and level standards are completely different. Replacing will burn out the 5V TTL load or module. If mixed high and low voltage outputs are required, a 1746-OB/OV (24V) and a 1746-OG16 can be used simultaneously in the rack, with separate wiring.

Q5: What is the product warranty and delivery time?

A: Brand new original products come with the original factory standard warranty. In-stock items can be shipped out on the same day. Delivery time for bulk orders can be negotiated.

Business Contact Information

Manager: Leonia

Email: sales@mvme.cn

Whatsapp: +8618030175807

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Allen-Bradley 1746-OG16 5V TTL Output Module for SLC500 Systems: Available Now, Perfectly Connected to Low-Speed Digital Displays and Logic Chips2026-06-26