1790D-TN4C0 Allen-Bradley Analog Input Module 4-Ch 0-20mA

1790D-TN4C0 Allen-Bradley 4-Channel Analog Current Input Module

Product Introduction

The 1790D-TN4C0 from Allen‑Bradley belongs to the CompactBlock LDX I/O family. This module provides four single‑ended, nonisolated analog input channels. You can configure the current range to either 0‑20 mA or 4‑20 mA. Its 12‑bit unipolar resolution delivers precise measurements. For the 4‑20 mA range, resolution is 3.90 µA/bit. For the 0‑20 mA range, it is 4.88 µA/bit. The module outputs binary data from 0000 to 0fff at full scale.

Additionally, this device requires no field calibration, which saves maintenance time. Its conversion time is only 10 milliseconds per channel. Therefore, the 1790D-TN4C0 works well in fast control loops and monitoring applications.

Technical Specifications

• Input channels: 4, single‑ended, nonisolated

• Current input ranges: 0‑20 mA or 4‑20 mA (software configurable)

• Default range: 4‑20 mA

• Resolution: 12 bits unipolar (1/4096 max)

• Overall accuracy: 0.2% full scale @ 0…55 °C

• Input impedance: 249 Ω

• Conversion time: 10 ms per channel

• Insulation resistance: 20 MΩ min @ 250V dc (between insulated circuits)

• Isolation: I/O to logic uses photocoupler isolation (tested at 1250V ac rms for 60 s). DeviceNet to logic and field power are nonisolated.

Power Requirements and Dissipation

The 1790D-TN4C0 needs two power supplies. First, the DeviceNet power supply operates at 24V dc nominal with a voltage range of 11…28.8V dc. Its maximum power dissipation is 1.2 W @ 28.8V dc. Second, the field power supply requires 24V dc nominal (21.6…26.4V dc). It dissipates up to 1.5 W @ 26.4V dc.

Mechanical and Environmental

• Weight: 0.38 lbs (0.17 kg)

• Wiring terminal: M3.0 screw type, max torque 7 lb‑in (use copper or copper‑clad aluminum conductors)

• Indicators: 4 red/green I/O status LEDs

• Expansion: The base unit accepts up to two discrete expansion modules

Installation Guidelines

Follow these steps to install the 1790D-TN4C0 correctly.

1. Ensure the DeviceNet network is powered off before wiring.

2. Connect the field power supply (21.6‑26.4V dc) to the appropriate terminals.

3. Wire analog current signals (0‑20 mA or 4‑20 mA) to the input channels.

4. Tighten terminal screws to 7 lb‑in maximum. Do not overtighten.

5. Configure the input range via software.

6. Apply power and check the LED status indicators.

Furthermore, always use shielded cables for analog signals to reduce noise. Keep field wiring separate from high‑voltage cables.

Packaging List

• 1790D-TN4C0 module (1 unit)

• Terminal block (pre‑installed)

• Quick start guide (paper)

Note: No certificates or warranty documents are included in the package.

Shipping

We ship worldwide via FedEx, UPS, or DHL. Your order will be dispatched within 1‑2 business days.

Frequently Asked Questions (FAQ)

1. Can the 1790D-TN4C0 accept 4‑20 mA signals without configuration?
Yes. The default input range is 4‑20 mA. However, you can change it to 0‑20 mA through software.

2. Does the 1790D-TN4C0 require periodic calibration?
No. The module needs no calibration, as stated in the official specifications.

3. How many expansion modules can I add to the 1790D-TN4C0 base?
You can add up to two discrete expansion modules.

4. What is the conversion speed of this analog input module?
The 1790D-TN4C0 converts each channel in 10 milliseconds. For four channels, the total scan time is 40 milliseconds.

5. Can I use this module with a 24V dc power supply that has a ±10% variation?
Yes. The field power supply accepts 21.6…26.4V dc, and the DeviceNet supply accepts 11…28.8V dc. A nominal 24V dc supply fits well within these ranges.