Allen-Bradley 1746-IN16 24V AC/DC Input Module

1746-IN16 SLC 500 Digital AC/DC Input Module

Product Introduction

The 1746-IN16 is a versatile digital input module from the Allen‑Bradley SLC 500 series. This unit features sixteen sinking channels. It accepts a wide voltage range of 24V AC or 24V DC. Many engineers prefer this module because it handles both AC and DC signals in one device.

Additionally, the 1746-IN16 draws only 0.085A (85 mA) from the 5V DC backplane. This low current consumption saves power in large I/O racks. Furthermore, each channel has a dedicated LED indicator. These lights show the active state of every input. For instance, you can quickly troubleshoot a field device by checking the corresponding LED.

Technical Specifications

The 1746-IN16 operates with a nominal input current of 8 mA at 24V for both AC and DC. Its off‑state current is just 1 mA, which prevents false triggering from leakage currents.

Key electrical parameters include:

• Inputs: 16 (sinking type)

• Voltage range: 10–30V AC/DC (nominal 24V)

• Frequency (AC): 47–63 Hz

• Signal delay (DC): 15 ms (ON/OFF and OFF/ON)

• Signal delay (AC): 25 ms (ON/OFF and OFF/ON)

• Off‑state current max: 1 mA

• Backplane current (5V DC): 85 mA

• Backplane current (24V DC): 0 mA

Application notes:
This module works for general‑purpose discrete input sensing. You can connect pushbuttons, limit switches, proximity sensors, and relay contacts. However, always verify that your field devices operate within the 10–30V range. Exceeding 30V may damage the 1746-IN16.

Power and Heat Dissipation

The 1746-IN16 manages heat efficiently in dense control cabinets. Its total heat dissipation reaches 6 Watts when all channels are active. Additionally, each point dissipates 0.35 Watts at nominal current.

Power specifications include:

• Minimum watts: 0.425 (with all channels off)

• Total watts: 6 Watts (all channels on at 24V, 8 mA)

• Watts per point: 0.35

Therefore, you should calculate total cabinet heat load before installation. Proper ventilation extends the life of the 1746-IN16 and surrounding modules.

Mechanical and Environmental Ratings

The 1746-IN16 shares the same environmental robustness as other SLC 500 modules. Its operating temperature range is 0°C to 60°C (32°F to 140°F). Non‑operating temperatures span from -40°C to 85°C (-40°F to 185°F).

Other environmental specifications:

• Relative humidity: 5% to 95% non‑condensing

• Operating vibration: 1.0 g at 5–2000 Hz

• Operating shock: 30 g

• Step response: 100 ms in, 2.5 ms out

Moreover, the 1746-IN16 operates reliably in Pollution Degree 2 environments. This unit is supplied as open‑type equipment for industrial control panels. Only trained personnel should access the enclosure containing this module.

Installation Guidelines

Installing the 1746-IN16 requires minimal effort. First, cut all power to the SLC 500 chassis before insertion. Next, align the module with the slot guides in any 1746 chassis. Then push firmly until the backplane connectors engage securely.

Wiring instructions:
Use 1746-HT or 1746-HCA I/O connection blocks for field wiring. Connect the 24V AC or DC common to the appropriate terminal. Each input channel connects to a field device contact. The 1746-IN16 expects sinking inputs, meaning the common is positive and the inputs switch to common (negative).

Important precautions:

• Do not apply AC and DC signals to different channels simultaneously unless they share a common isolated group

• Keep AC and DC wiring separate to avoid noise coupling

• Always secure the module with the chassis retaining latch

Hazardous Environment Usage

The 1746-IN16 can operate in certain hazardous locations when properly installed. However, you must follow strict safety procedures. Keep equipment powered only until the area is secured and power is cut. Never remove or insert this module in a hazardous zone with power applied.

Packaging List

Your shipment includes the following items:

• One Allen‑Bradley 1746-IN16 digital AC/DC input module

• One product information sheet

• One anti‑static protective bag

Note: This package does not include terminal blocks, cables, mounting hardware, certificates, or warranty documents. Terminal blocks such as 1746-HT and 1746-HCA must be ordered separately.

Shipping Information

We ship all orders using trusted global carriers. Your 1746-IN16 module will be dispatched via:

• FedEx

• UPS

• DHL

Tracking numbers will be provided within 24 hours of shipment. Standard delivery takes 3–7 business days depending on your location.

Frequently Asked Questions (FAQ)

1. Can I mix AC and DC inputs on the same 1746-IN16 module?
Yes, the 1746-IN16 accepts both 24V AC and 24V DC signals on different channels. However, ensure that all inputs share the same common reference. Do not mix AC and DC commons on the same group.

2. What is the difference between the 1746-IN16 and the 1746-IM8?
The 1746-IN16 accepts 24V AC or DC and has 16 channels. The 1746-IM8 accepts 170–265V AC and has only 8 channels. Choose the 1746-IN16 for low-voltage applications and the IM8 for high-voltage AC sensing.

3. Why are my input LEDs not turning on?
First, verify your field device provides at least 10V (for DC) or 10V AC (for AC). Next, check the wiring on your 1746-HT or 1746-HCA block. Then ensure the common connection is correct. Finally, confirm your SLC processor's configuration enables the slot.

4. What is the signal delay for AC versus DC on the 1746-IN16?
For DC signals, the 1746-IN16 has a 15 ms delay. For AC signals, the delay is 25 ms. This difference exists because the module requires more filtering time for AC waveforms. Plan your program's timing accordingly.

5. Can I install the 1746-IN16 in any SLC 500 chassis slot?
Yes, the 1746-IN16 occupies a single slot and fits any 1746 series chassis. You can place it in the local chassis with the processor or in an expansion chassis. There are no slot restrictions for this module.