6ES7400‑2JA00‑0AA0 | Siemens UR2‑H Rack for S7‑400H Redundant PLC

What this guide covers: A commercial buying guide centered on the 6ES7400-2JA00-0AA0 Siemens SIMATIC S7-400H PLC — the UR2-H central rack of Siemens’ fault-tolerant controller line. The Mitsubishi MDS-A-BT-4 servo drive appears as the practical integration partner, since most buyers sourcing this rack do so to keep servo-driven production lines running.

• What it is: The 6ES7400-2JA00-0AA0 is the UR2-H rack for the S7-400H redundant system — not a CPU, but the housing that carries two synchronized CPU subracks.
• Specifications: 9 slots per subrack, 120/230V AC supply, ~4.557 kg, −25°C to +60°C, IEC 61131-2/3 certified.
• Redundancy: Fiber-optic sync modules link primary and standby CPUs; failover completes in under 100 ms without interrupting servo motion.
• Price: Listed near $309 new and original from SieSourceHK (down from $370.80); other channels range roughly $277–$287.
• Integration: MDS-A-BT-4 drives connect via ±10V analog commands or PROFIBUS DP / PROFINET with an option card.
• Procurement checklist: Verify originality, stock condition, warranty scope, protocol compatibility, environmental limits, and spare-part lifecycle before ordering.

Who should read it: Maintenance planners, OEM project engineers, and B2B procurement teams evaluating the S7-400H for spare-part stocking or fault-tolerant line extensions.

The 6ES7400-2JA00-0AA0 is one of the most searched Siemens SIMATIC S7-400H order codes in the industrial spare-parts market. Buyers find it listed as a “rack,” yet many confuse it with a CPU card or assume it functions as a standalone controller.

This guide explains what this exact module is, what it costs, and how it fits into a fault-tolerant S7-400H system alongside servo drives such as the Mitsubishi MDS-A-BT-4.

What Is the 6ES7400-2JA00-0AA0 Siemens SIMATIC S7-400H PLC?

The 6ES7400-2JA00-0AA0 is the UR2-H central rack of the SIMATIC S7-400H fault-tolerant system. It is not a CPU. It is the mechanical and electrical backbone that holds two synchronized CPU subracks, enabling the H-system’s redundant operation.

Decoding the order code clarifies the product:

• 6ES7 — SIMATIC S7 programmable controller family
• 400 — S7-400 platform (mid-to-high-end process automation)
• 2JA00 — UR2-H rack, the central rack for the H (high-availability) system
• 0AA0 — hardware version designation

In a high-availability line, two CPUs run the same program in parallel. The UR2-H rack provides the nine slots per subrack, the backplane bus, and the mechanical mounting for that arrangement. One CPU serves as master; the other tracks in hot-standby.

This distinction matters at purchase time. A buyer who orders the 6ES7400-2JA00-0AA0 expecting a processor will also need the CPU modules, power supplies, and sync modules that the rack was designed to host.

6ES7400-2JA00-0AA0 Specifications: What the Order Code Tells You

The UR2-H rack is a mechanical and electrical assembly, so its specification sheet reads differently from a CPU datasheet. Verified parameters from supplier documentation:

The rack’s operating range matters in real plants. At −25°C to +60°C, it tolerates unheated switchgear rooms and warm cabinets. Electrical noise immunity follows IEC 61131-2, the standard most automation engineers treat as the baseline for panel-mounted controllers.

The S7-400H system itself is programmed in STEP 7 (or TIA Portal for compatible CPUs) using standard LAD, FBD, or STL. Fault-tolerant configuration adds redundant I/O mapping, sync module setup, and OB 70/OB 72 handling — no specialized programming language is required.

How the S7-400H Redundant Architecture Works With Servo Drives

The UR2-H rack’s purpose is continuity. Two synchronized CPU subracks maintain identical program state over fiber-optic sync modules, linkable up to 10 meters apart. If the master CPU fails, the standby takes over in under 100 milliseconds.

For motion control, that speed is the deciding factor. A servo drive — such as the Mitsubishi MDS-A-BT-4 — receives position or velocity commands from the redundant controller. When failover occurs, the drive never loses its command source long enough to trip. Continuous processes like web handling, coating lines, and extrusion keep running without lost product.

Integration between the S7-400H and MDS-A-BT-4 follows one of two paths:

1. Analog command signals — ±10V velocity or torque reference wired from a PLC analog output module directly to the drive terminals. Simplest retrofit path; no fieldbus reconfiguration.
2. Fieldbus communication — PROFIBUS DP or PROFINET, requiring a compatible communication option card on the drive.

Retrofit projects on existing S7-400H lines usually prefer the analog path. It avoids reconfiguring the PLC’s communication bus and lets maintenance teams swap drives without commissioning changes.

6ES7400-2JA00-0AA0 Price: What to Pay and What Drives Cost

The 6ES7400-2JA00-0AA0 Siemens SIMATIC S7-400H PLC rack is listed at approximately $309 through the referenced platform SieSourceHK, down from an original price of $370.80. Comparable listings across B2B channels:

SieSourceHK describes the module as new, original, and stocked for immediate shipment. For maintenance planners who cannot absorb multi-week lead times on critical spare parts, stock availability often outweighs a small price difference.

Transaction prices depend on several factors beyond the list price:

• Order quantity — volume discounts typically start above 5–10 units
• Condition — new original, refurbished, or surplus stock
• Documentation package — datasheets, test certificates, origin documentation
• Shipping region — import duties and logistics vary by destination
• Lead time requirements — expedited shipping adds roughly 15–25% to unit cost

Where the S7-400H Excels: Real Applications and Integration Logic

The 6ES7400-2JA00-0AA0 delivers the most value where a controller failure is too expensive to tolerate. That profile fits several production environments at once:

• Process continuity is non-negotiable. Chemical dosing, continuous web processing, and furnace temperature control all benefit from redundant supervision. A CPU fault mid-batch can destroy hours of throughput.
• Motion precision matters more than peak speed. The MDS-A-BT-4’s 50 Hz speed response frequency handles positioning, tensioning, and indexing. It will not match the 2.5 kHz response of Mitsubishi’s newer MR-J4 series, but for maintenance-driven line support it performs reliably.
• Legacy infrastructure must be preserved. Replacing an S7-400H with a newer controller generation forces program migration, protocol rework, and operator retraining. Keeping the same rack model simplifies spare-part management.

Typical deployment scenarios:

• Automotive component machining lines — servo-driven indexing tables supervised by S7-400H redundant logic
• Pharmaceutical packaging — fill-and-seal stations where a controller fault could contaminate product
• Steel mill auxiliary drives — roll positioning and tension control in harsh thermal environments
• Textile manufacturing — multi-axis winding with tension regulation under continuous operation

In each case, the S7-400H provides decision logic and redundancy. The MDS-A-BT-4 provides the motion. Together they form a system that tolerates single-component failure without halting production.

Sourcing the 6ES7400-2JA00-0AA0: A Procurement Checklist for Legacy PLCs

Procurement teams sourcing the 6ES7400-2JA00-0AA0 Siemens SIMATIC S7-400H PLC should verify several factors before finalizing any purchase:

1. Confirm you are buying the rack, not assuming a CPU. The 6ES7400-2JA00-0AA0 is the UR2-H rack. Confirm your CPU modules, power supplies, and sync modules are available before committing to a full system build.
2. Originality verification. Counterfeit automation components circulate in gray-market channels. Request factory traceability numbers, original packaging photos, and supplier authorization documentation where available.
3. Stock condition disclosure. “New original” should mean unopened factory packaging. “Refurbished” should include a test report specifying replaced components and the functional tests performed.
4. Warranty terms. Supplier listings show warranty periods ranging from 12 to 18 months. Verify whether the warranty covers replacement shipping costs or only the unit itself.
5. Communication protocol compatibility. If pairing the rack with drives over PROFINET, confirm each drive carries the correct option card or that a protocol converter is included.
6. Spare-part lifecycle status. The S7-400H is a mature platform with a large installed base, but replacement-part availability narrows over time. Confirm ongoing stock from your chosen supplier and consider stocking critical spares.

Frequently Asked Questions

Is the 6ES7400-2JA00-0AA0 a CPU or a rack?

The 6ES7400-2JA00-0AA0 is the UR2-H central rack of the S7-400H fault-tolerant system. It is not a CPU. It hosts two synchronized CPU subracks, each with nine slots, plus power supplies and sync modules.

Can the S7-400H control Mitsubishi MDS-A-BT-4 servo drives?

Yes. Integration works through ±10V analog command signals from a PLC analog output module, or over PROFIBUS DP / PROFINET when the drive carries a compatible communication option card. Analog wiring is the most common retrofit path.

Is the S7-400H still supported by Siemens?

Siemens continues to support the S7-400H platform with documentation, service, and spare-part channels, though the product line is mature and newer alternatives (S7-1500H) exist. New original modules remain available through authorized distributors and stocked suppliers.

What is the typical lead time for the 6ES7400-2JA00-0AA0?

From stocked suppliers like SieSourceHK, lead time is typically 3–7 business days for international shipping. Custom configurations or bulk orders may extend this to 2–4 weeks.

Does the S7-400H require specialized programming?

No. The system uses standard STEP 7 (or TIA Portal for compatible CPUs) with LAD, FBD, or STL. Fault-tolerant configuration adds redundant I/O mapping, sync module setup, and OB 70/OB 72 handling, but no dedicated fault-tolerant language.

Is the 6ES7400-2JA00-0AA0 suitable for new builds or only maintenance?

Both. Cost-sensitive or standardized legacy environments still deploy the S7-400H in new projects. Most current demand, however, comes from maintenance, line extension, and spare-part stocking for existing installations. For greenfield high-availability systems, evaluate the S7-1500H as a newer alternative.

What warranty should I expect when sourcing this module?

New original units typically carry 12–18 month supplier warranties. The exact scope depends on the distributor’s terms. Always confirm whether the warranty covers return shipping and on-site replacement labor.

Reference Sources

1. Siemens AG. “SIMATIC S7-400H Fault-Tolerant Systems System Manual.” Siemens Industry Support. https://support.industry.siemens.com/cs/attachments/82478488/S7_400_h_en_en-US.pdf
2. Siemens AG. “S7-400H Product Information and Ordering Data.” Siemens Mall. https://mall.industry.siemens.com/mall/en/za/Catalog/Products/10121879
3. SieSourceHK. “6ES7400-2JA00-0AA0 Siemens SIMATIC S7-400 / S7-400H PLC — New and Original in Stock.” https://siesourcehk.com/product/siemens-module-6es7400-2ja00-0aa0/
4. IEC 61131-2: Programmable Controllers — Equipment Requirements and Tests. International Electrotechnical Commission. https://webstore.iec.ch/publication/4496
5. IEC 61131-3: Programmable Controllers — Programming Languages. International Electrotechnical Commission. https://webstore.iec.ch/publication/4536
6. Industrial Monitor Direct. “Siemens S7-400H Hot Redundant CPU Advantages Over Standalone.” https://industrialmonitordirect.com/blogs/knowledgebase/siemens-s7-400h-hot-redundant-cpu-advantages-over-standalone
7. EuoSource. “MDS-A-BT-4 Mitsubishi Servo Drive — Product Specifications.” https://euosource.com/products/mds-a-bt-4-mitsubishi-servo-drive