In short
A technical walkthrough for replacing and configuring the Allen-Bradley POINT I/O 1734-AENTR dual-port EtherNet/IP adapter, including compatibility rules and step-by-step setup.
Overview
The Allen-Bradley POINT I/O system is one of the most widely deployed distributed I/O families in industrial automation. At the heart of most modern POINT I/O assemblies is the 1734-AENTR, an EtherNet/IP dual-port adapter that enables high-speed communication between a Logix5000 controller and the distributed I/O rack.
Whether you are upgrading an older, single-port 1734-AENT adapter, swapping out a failed early-generation 1734-AENTR Series A or B unit, or transitioning parts during a systematic facility modernization, understanding the precise hardware and software migration requirements is critical. This guide provides the complete technical details required to execute a seamless, low-downtime replacement of the 1734-AENTR adapter.
Legacy Product Information
The 1734-AENTR has gone through several physical and firmware hardware revisions since its introduction. Understanding the specs of your existing adapter helps minimize installation errors, especially regarding backlight power demands and network topologies.
- Catalog Number: 1734-AENTR (Dual-port EtherNet/IP Adapter)
- Input Voltage: 24V DC nominal (10–28.8V DC range)
- POINTBus Current Output: 1000 mA maximum @ 5V DC (pins 1 & 2 on the backplane)
- Network Topologies Supported: DLR (Device Level Ring), Linear, and Star topologies
- Max Number of Sub-Modules: Up to 63 physical modules per network drop (with appropriate 1734-EP24DC expansion power supplies)
- Current Lifecycle Status: Active. However, earlier iterations (specifically Series A and Series B) are legacy/discontinued, with Series C being the current production standard.
Common historical applications include distributed field sensor blocks, localized valve manifold control banks, and machine-to-machine interlocking lines where DLR ring resilience is required.
Recommended Replacements
When planning a replacement, you must choose either a modern revision of the same adapter, a single-port variation if your loop topology allows, or a migration path to the next-generation platform.
| Legacy P/N | Recommended Replacement | Notes |
|---|---|---|
| 1734-AENTR Series A/B | 1734-AENTR Series C | Direct drop-in functional replacement. Class 1 connection capacity upgraded. Requires careful verification of electronic keying parameters in Studio 5000. |
| 1734-AENT (Single-Port) | 1734-AENTR (Dual-Port) | Often used to upgrade old networks to high-availability Device Level Ring (DLR) layouts. Mechanical footprint is identical, but backplane configuration within the PLC project must be updated to reflect the "R" dual-port version. |
| 1734-AENTR | 5069-AENTR | Next-generation Compact 5000 I/O EtherNet/IP adapter. Not a physical drop-in. Requires upgrading the entire I/O rack to 5069 modules, but offers drastically increased speed, embedded gigabit performance, and more robust backplane power. |
Compatibility Considerations
Wiring and Footprint
The physical dimensions of the 1734-AENTR Series C are identical to Series A/B (55.4 x 118.3 x 133.4 mm). It mounts directly onto standard Top-Hat DIN-rails (35mm).
- Power Connection: Power is delivered via standard 4-point screw-clamp or spring-clamp connectors. If you are replacing a Series A/B with a Series C, you can typically unplug the terminal block from the old adapter and insert it directly into the new one without disconnecting individual copper wires.
- Network Wiring: Category 5e (or better) shielded twisted-pair cables terminated with standard RJ45 connectors are required. The physical ports on the Series C are rotated slightly to accommodate standard industrial boot-style Ethernet connectors more easily.
Software and Firmware
Replacing an older 1734-AENTR requires confirming your RSLogix 5000 / Studio 5000 Logix Designer version and your firmware compatibility:
- Add-On Profiles (AOP): Series C adapters may require an updated POINT I/O AOP downloaded from the Rockwell Automation Product Support Center if you are running older Logix Designer versions (typically v20 or earlier).
- Electronic Keying: This is the most common point of installation failure. By default, many old PLC programs are configured with "Exact Match" electronic keying. When a Series A or B unit with firmware v3.xx is replaced with a Series C unit running firmware v4.xx or v5.xx, the PLC will reject the connection because of the mismatch.
- Keying Modes: Change the module keying configuration in Studio 5000 to "Compatible Module" to allow future firmware upgrades without causing controller faults.
Upgrade Benefits
Upgrading from an older legacy series or standard 1734-AENT adapter to a modern 1734-AENTR Series C provides several key advantages:
- Enhanced Security Support: Series C hardware features modern codebase architecture, allowing for future firmware upgrades that improve robustness against network vulnerability attacks.
- Improved Processing Power: Features a faster internal ASIC chip, reducing cycle times and handling background messaging workloads much more efficiently.
- Advanced DLR Diagnostics: Provides richer diagnostics to the Logix processor, allowing you to quickly locate network breaks on a Device Level Ring.
- Reduced Commissioning Footprint: Modern manufacturing changes make the onboard rotary switches easier to access and manipulate in tight cabinets.
Common Migration Challenges
- Chassis Size Parameters: When a new adapter is brought online, its default "Chassis Size" parameter is typically set to 1 (meaning only the adapter itself is present). If you have 8 I/O modules connected, the adapter's status LED will blink Red, and the PLC will report an "I/O Connection Error". You must configure and apply the correct chassis size using Studio 5000 or the web page of the adapter.
- Network Node Address Conflicts: The rotary switches on the unit control the last octet of the IP address (192.168.1.xxx). If these switches are set to 999 or are out of alignment, the module might default to DHCP/BOOTP mode unexpectedly, resulting in control loss.
- Inadequate Backplane Current: The 1734-AENTR translates 24V DC input into 5V DC POINTBus backplane power, rated at 1000 mA. Heavy industrial modules (e.g., analog inputs, counter modules, or thermocouple modules) draw significant backplane power. Ensure your new module configuration has the exact same power distribution layout as the original to prevent the adapter's built-in power supply from shutting down under overcurrent.
Step-by-Step Replacement Procedure
Follow this technical procedure to install and configure your new 1734-AENTR adapter:
1. Preparatory Phase & Backup
- Ensure the system is in a safe state. De-energize control power to the I/O slice assembly.
- Record the position of the existing module's three rotary address switches (located on the top-front face of the current adapter).
- Open your Studio 5000 project and change the controller mode to Offline. Open the module properties for the 1734-AENTR and record the configured IP address, subnet mask, and chassis size.
2. Physical Removal
- Disconnect the RJ45 Ethernet communication cables and label them Port 1 vs. Port 2 if they are part of a DLR circuit.
- Unplug the 4-pin Removable Terminal Block (RTB) housing the 24V supply lines by pulling the orange pull-tab straight out.
- Slide the orange DIN-rail locking mechanism down with a flathead screwdriver.
- Slide the base safety latch horizontally to release the adapter from the adjacent physical I/O bases, then pull the adapter forward off the DIN rail.
3. Setting the Hardware Parameters on New Adapter
- On the replacement 1734-AENTR, set the three rotary switches to match the recorded setting of the old module.
- Note: If you are using a static address in the
192.168.1.xxxsubnet, set the switches directly to the last octet value (e.g.,124). - If the network uses DHCP/BOOTP or a manual static configuration on a different subnet, set the switches to
999(or888on older Series to trigger a factory out-of-box reset, then configure).
- Note: If you are using a static address in the
4. Installation and Wiring
- Push the new 1734-AENTR straight onto the DIN rail until it clicks securely into place.
- Hook the side interlock back onto the first I/O module base.
- Reconnect the standard 4-pin RTB power connector.
- Reconnect the RJ45 Ethernet cables back into their respective Ports.
5. Commissioning & Software Initialization
- Re-apply 24V DC power to the adapter.
- Open the Rockwell BOOTP-DHCP Utility (if switches are set to 999 or manual mapping is required) to assign the target static IP address, gateway, and subnet mask. If you set the switches to a numerical IP (e.g., 001–254), skip the utility.
- Open your web browser, enter the adapter's IP address, and navigate to the Chassis Configuration page. Click Set Chassis Size and change it to represent the actual number of modules connected to the right of the adapter (plus 1 for the adapter itself, if designated by older firmware).
- Online in Studio 5000, verify the module connection state. If connection fails with a "Keying Error", adjust the module property keying definition to "Compatible Module" and download the project configuration.
- Ensure the "Module Status" (MS) and "Network Status" (NS) LEDs on the physical unit remain solid Green.
Frequently Asked Questions
Q1: Can I replace a 1734-AENT (single-port) with a 1734-AENTR (dual-port) without modifying my code?
A: No. Because the dual-port module uses a different electronic profile inside the PLC hardware definition tree, you must modify your Logix offline project. In your I/O Configuration tree, delete the 1734-AENT adapter and add the 1734-AENTR adapter with the matching IP address, then move all sub-modules to the new tree configuration.
Q2: What does a flashing red Port Status (LINK1/LINK2) LED mean?
A: A flashing red network LED on the ports indicating a physical layer issue, high packet loss, or a broken ring within a Device Level Ring (DLR) configuration. Check Ethernet crimps, electromagnetic noise interference, and port settings.
Q3: Why does my PLC show a yellow warning triangle even though the 1734-AENTR LEDs are solid green?
A: This indicates an internal connection mismatch or connection failure in Logix. Check the "Connection" tab of the adapter's module properties. Ensure the "Chassis Size" programmed inside the controller's module configuration matches the exact physical number of slots on the chassis rail.
Q4: Can I complete a replacement under power (Hot Swapping)?
A: No. Unlike standard POINT I/O terminal bases, the 1734-AENTR serves as the primary system power supplier for the backplane logic. Removing it while active will instantly lose backplane power, resulting in complete system failure for all downstream modules.
Related Products & Families
To complete your system maintenance or overhaul, Palm Parts Solution carries an extensive inventory of auxiliary components in the POINT I/O family:
- 1734-IB8: 8-Channel 24V DC Sink Input Module
- 1734-OB8: 8-Channel 24V DC Source Output Module
- 1734-EP24DC: POINT I/O 24V DC Expansion Power Supply (required for longer rails)
- 1734-IE2C / 1734-OE2C: 2-Channel Analog Input and Output modules
Need Help?
Replacing or upgrading older Allen-Bradley automation systems can raise unexpected compatibility and software setup issues. Palm Parts Solution has inventory to resolve these bottlenecks quickly. We supply high-quality new, refurbished, and hard-to-find surplus industrial automation components—including the 1734-AENTR adapter—backed by a comprehensive warranty to minimize your facility’s unexpected downtime. Contact our technical support and parts team today to secure the exact industrial hardware you need.