Product Overview

The Allen-Bradley 1794-IH16 belongs to the Flex I/O 1794 series. This module provides sixteen non-isolated digital input points. It operates specifically at 125V DC nominal voltage. The 1794-IH16 suits high voltage DC applications in industrial control systems. Its hazardous location approval allows installation in explosive or dangerous areas.

Technical Specifications

The 1794-IH16 operates with a nominal voltage of 125V DC. Its minimum on-state input voltage is 90V DC. The maximum on-state voltage reaches 146V DC. The maximum off-state voltage rating is 20V DC.

Current ratings for the 1794-IH16:

• Minimum on-state input current: 1 mA

• Nominal on-state input current: 2 mA at 125V DC

• Maximum on-state input current: 3 mA

• Maximum off-state input current: 0.8 mA

Power and thermal data:

• Maximum power dissipation: 6 Watts at 146V DC

• Maximum thermal dissipation: 20.47 BTU per hour at 146V DC

• All sixteen inputs share the same electrical reference (non-isolated)

Physical dimensions (installed):

• Width: 3.7 inches (94 mm)

• Height: 3.7 inches (94 mm)

• Depth: 2.7 inches (69 mm)

Physical dimensions (uninstalled):

• Width: 1.8 inches (46 mm)

• Height: 3.7 inches (94 mm)

• Depth: 2.1 inches (53 mm)

Hazardous Location Approval

The 1794-IH16 carries North American Hazardous Location approval. This certification meets safety standards for Class I, Division 2 environments. You can install this module in areas with flammable gases or vapors. The approval reduces the need for expensive explosion-proof enclosures. Always follow local installation codes when using the 1794-IH16 in hazardous areas.

Compatible Terminal Bases

The 1794-IH16 requires a Flex I/O terminal base for proper operation. The terminal base provides field wiring connections and DIN rail mounting. Compatible terminal bases for this module are:

• 1794-TB3 terminal base

• 1794-TB3S terminal base (screw type)

• 1794-TB3K terminal base (spring clamp)

• 1794-TB3SK terminal base (spring clamp with shielding)

These terminal bases allow hot insertion of the 1794-IH16. You can remove or replace the module without removing field wiring. This feature reduces system downtime during maintenance.

Input Characteristics

The 1794-IH16 uses sinking input architecture. Each channel expects a 125V DC signal from a field device. Common compatible devices include high voltage proximity sensors, limit switches, and relay contacts. The module does not provide channel-to-channel isolation. All sixteen inputs share a common reference point. Consider this when wiring devices from different power sources.

Installation Guidelines

Install the 1794-IH16 onto a compatible terminal base first. Mount the terminal base onto a standard DIN rail using the locking mechanism. Push the module firmly until the backplane connector fully seats. Secure the module with the terminal base locking tab. Wire field devices according to the terminal base manual. Use wire rated for 125V DC operation with proper insulation.

Do not apply voltage exceeding 146V DC to any input channel. Keep the ambient temperature within operating limits. The 1794-IH16 has no internal fuse protection. Use external fusing for each input circuit if required by your application.

Package Contents

• One Allen-Bradley 1794-IH16 Flex I/O Digital Input Module

• One keyswitch label (position label for terminal base)

• Product identification label

Frequently Asked Questions (FAQ)

1. What is the nominal voltage rating of the 1794-IH16?
The 1794-IH16 has a nominal operating voltage of 125V DC. It accepts voltages from 90V DC to 146V DC.

2. Is the 1794-IH16 approved for hazardous locations?
Yes, the 1794-IH16 carries North American Hazardous Location approval. It suits Class I Division 2 industrial environments.

3. How many input points does this module provide?
The 1794-IH16 provides sixteen digital input points. None of these channels are isolated from each other.

4. What terminal bases work with the 1794-IH16?
The 1794-IH16 works with 1794-TB3, 1794-TB3S, 1794-TB3K, and 1794-TB3SK terminal bases. Each base type offers different wiring options.

5. What is the nominal input current at 125V DC?
The 1794-IH16 draws 2 mA nominal input current at 125V DC. The maximum on-state current is 3 mA per channel.