Allen-Bradley 1756-DMA31 Replacement for ControlLogix

Product Overview

Allen-Bradley 1756-DMA31 Replacement for ControlLogix: Smooth Transition, Zero Compromise

When a legacy drive interface fails or a ControlLogix system requires modernization, procurement teams cannot afford ambiguity. The Allen-Bradley 1756-DMA31 SynchLink Drive Interface Module is a purpose-built solution for engineers managing the transition from aging 1756-series drive coordination architectures to a fully compatible, production-ready replacement — without rewriting ladder logic, rewiring terminal blocks, or reconfiguring the backplane.

The 1756-DMA31 occupies a standard ControlLogix 1756 chassis slot and communicates over the SynchLink fiber-optic network, a high-speed deterministic link designed specifically for coordinating multi-axis drive systems. Whether your facility operates PowerFlex 700S drives, PowerFlex 7000 medium-voltage drives, or legacy 1336 PLUS II drives connected through a SynchLink ring, the 1756-DMA31 serves as the authoritative master interface — synchronizing torque references, speed references, and status feedback across all connected drive nodes with microsecond-level determinism.

For plants running continuous production lines in steel rolling mills, paper machines, mining hoists, or large-scale pump stations, the SynchLink architecture eliminates the latency and jitter associated with conventional EtherNet/IP or DeviceNet polling. The 1756-DMA31 maintains this advantage in the replacement unit, ensuring that your upgraded system inherits the same real-time coordination performance as the original installation.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful 1756-DMA31 replacement rarely happens in isolation. In most ControlLogix-based drive coordination systems, the SynchLink interface module works in concert with a broader ecosystem of components that must be verified — and in some cases, simultaneously upgraded — to ensure a clean cutover.

The 1756-DMA31 resides in a 1756 chassis alongside the ControlLogix controller itself, typically a 1756-L71, 1756-L73, or 1756-L83E processor. If the controller firmware is being updated as part of the migration, the module’s electronic data sheet (EDS) and module profile must be confirmed compatible in Studio 5000 Logix Designer before the replacement is commissioned. In many retrofit projects, the 1756-EN2T EtherNet/IP communication module is also present in the same chassis, handling supervisory SCADA communications while the 1756-DMA31 manages the real-time SynchLink drive network — both must remain operational during the transition.

On the drive side, the SynchLink fiber ring typically connects to PowerFlex 700S drives equipped with the 20-COMM-S SynchLink adapter card. If any of these adapter cards are also at end-of-life, sourcing them alongside the 1756-DMA31 replacement ensures the entire fiber ring is refreshed in a single maintenance window, avoiding a second unplanned outage. For medium-voltage applications, PowerFlex 7000 drives with integrated SynchLink ports connect directly without an adapter, but their firmware version must be validated against the replacement module’s supported node list.

Terminal wiring for the fiber-optic ST connectors on the 1756-DMA31 is straightforward — the module uses standard 62.5/125 µm multimode fiber, and the existing fiber patch cables from the original installation can typically be reused without modification. If the fiber runs are being extended or rerouted during the retrofit, standard ControlLogix-compatible fiber patch assemblies are available and should be tested for continuity before the module is powered.

In chassis configurations where the 1756-DMA31 shares a rack with 1756-IB16 digital input modules, 1756-OB16E digital output modules, or 1756-IF8 analog input modules handling process feedback, the replacement procedure must account for the controller’s I/O tree — inhibiting the DMA31 module in the controller configuration before physical removal prevents nuisance faults from propagating to the I/O tree during the swap. A 1756-PSCA2 chassis adapter or 1756-RMC redundancy module, if present, should also be placed in the appropriate state before the replacement begins.

Retrofit Guidance FAQ

Q: Can I replace the 1756-DMA31 without modifying my existing RSLogix 5000 / Studio 5000 program?
A: In the vast majority of cases, yes. The 1756-DMA31 replacement uses the same module catalog number and electronic data sheet profile as the original. As long as the replacement unit carries the same or compatible firmware revision, the controller will recognize it automatically upon re-enabling the module in the I/O tree. No ladder logic changes, no tag remapping, and no drive parameter re-entry are required.

Q: Is the wiring and fiber connection identical to the original module?
A: Yes. The 1756-DMA31 uses standard ST-type fiber-optic connectors for the SynchLink ring. The existing fiber patch cables from your original installation can be reconnected directly to the replacement module. No rewiring of the control cabinet, terminal strips, or power distribution is required.

Q: What ControlLogix chassis and power supplies are compatible with this replacement module?
A: The 1756-DMA31 is compatible with all standard 1756-series chassis — including the 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17 — and operates with any standard 1756 power supply, including the 1756-PA72, 1756-PB72, and 1756-PA75. No chassis modification or power supply upgrade is required for the replacement.

Q: What if my system uses a mix of PowerFlex 700S and older 1336 PLUS II drives on the same SynchLink ring?
A: The 1756-DMA31 supports mixed SynchLink node configurations. The module manages each node independently on the fiber ring, so a combination of PowerFlex 700S drives with 20-COMM-S adapters and legacy 1336 PLUS II drives with SynchLink interface boards can coexist on the same ring without reconfiguration. Verify the node address assignments in your existing program match the physical ring topology before commissioning the replacement.

Warranty Assurance

Every 1756-DMA31 shipped by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes a structured pre-shipment inspection that includes visual examination for physical damage, connector integrity verification, firmware version confirmation, and functional power-on testing where applicable. Units that do not pass inspection are quarantined and never shipped.

If a warranty claim arises within the 12-month coverage period, TOPNLMS provides direct replacement support. Our technical team will coordinate the return, evaluate the returned unit, and dispatch a verified replacement with priority handling. Response times for warranty cases are typically within one business day of claim submission.

For procurement teams managing critical infrastructure, TOPNLMS maintains standing inventory of high-demand ControlLogix modules to support emergency replacement orders. Orders confirmed before the daily cutoff are processed for same-day or next-day dispatch, with DHL Express, FedEx International Priority, and UPS Worldwide Express available as shipping options to minimize plant downtime.

Long-term supply continuity is a core commitment. For facilities managing multi-year maintenance contracts or scheduled turnaround programs, TOPNLMS can discuss reserved stock arrangements to ensure the 1756-DMA31 and associated ControlLogix components remain available when your maintenance schedule requires them.