Siemens 6ES7972-0DA00-0AA0 PROFIBUS DP Terminator – SIMATIC NET

Siemens 6ES7972-0DA00-0AA0 — Active Bus Terminator for PROFIBUS DP Segment Integrity

In a PROFIBUS DP network, signal integrity at the physical layer is not a secondary concern — it is the foundation upon which all deterministic communication depends. The RS-485 differential bus used by PROFIBUS DP is a transmission line in the strict electrical sense: when a high-frequency signal propagates along a cable and encounters an impedance discontinuity at the cable end, a portion of that signal reflects back toward the source. At baud rates of 1.5 Mbit/s and above, these reflections arrive within the bit period of subsequent telegrams, causing voltage superposition that corrupts data frames. The Siemens 6ES7972-0DA00-0AA0 is the engineered solution to this problem — a 24 V DC-powered active bus terminator that maintains the correct characteristic impedance at each physical segment endpoint across the full PROFIBUS DP baud rate range from 9.6 kbit/s to 12 Mbit/s.

Unlike passive termination networks built into standard DB9 bus connectors, the 6ES7972-0DA00-0AA0 draws its operating power from an external 24 V DC supply rather than from the PROFIBUS VP (voltage plus) pin. This architectural distinction is significant: passive terminators that rely on VP power become non-functional when the device at the segment end is powered down for maintenance or fault isolation. The active terminator maintains its impedance-matching function regardless of the power state of the attached device, preserving bus stability during partial-system shutdowns — a scenario common in modular machine architectures and multi-zone process plants.

The component is classified within the SIMATIC NET PROFIBUS DP accessory portfolio and carries full compliance with IEC 61158 (fieldbus standard for industrial communication) and EN 50170 (general purpose field communication system). Its DB9 male/female pass-through connector design allows it to be inserted inline at any segment endpoint without interrupting the physical bus topology. The housing is rated for industrial ambient conditions, with an operating temperature range of 0 °C to +60 °C and resistance to the vibration and EMI environments typical of control cabinet installations.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The core termination circuit of the 6ES7972-0DA00-0AA0 implements the standard PROFIBUS DP termination network as defined in IEC 61158-2: a 390 Ω pull-up resistor from VP to line A, a 220 Ω characteristic impedance resistor between line A and line B, and a 390 Ω pull-down resistor from line B to DGND. In a passive implementation, VP is sourced from pin 6 of the DB9 connector — the device’s own supply. In the 6ES7972-0DA00-0AA0, the VP rail is replaced by the external 24 V DC input, regulated internally to the correct VP level. This decoupling is the hardware design decision that defines the product’s operational advantage.

EMC Design: The terminator housing incorporates a shielded metal enclosure that provides continuous shield continuity between the incoming cable shield and the outgoing bus connector. The shield connection is made at a single point within the terminator body, preventing ground loop formation while maintaining high-frequency shield effectiveness. Internal filtering on the 24 V DC supply input suppresses conducted interference from the power rail, preventing noise injection into the termination network — a failure mode observed in unfiltered active terminators operating in environments with variable-frequency drives or switched-mode power supplies on the same 24 V DC bus.

Impedance Stability Across Temperature: The resistor network uses metal-film components with a temperature coefficient of resistance (TCR) below 100 ppm/°C, ensuring that the 220 Ω characteristic impedance remains within ±5% across the full 0–60 °C operating range. At 12 Mbit/s, where the bit period is 83.3 ns and the signal rise time is approximately 30 ns, a 5% impedance deviation produces a reflection coefficient of 0.024 — well within the IEC 61158 tolerance for signal integrity. This thermal stability is not achievable with carbon-composition resistors used in lower-cost passive terminators.

Pass-Through Architecture: The DB9 pass-through connector allows the terminator to be installed at a segment endpoint that also serves as a device connection point — for example, at the last slave station on a segment. All signal pins are passed through transparently; only the termination network is inserted in parallel across lines A and B. This eliminates the need for a dedicated termination node at the segment end, reducing hardware count and cabinet space in installations where the last device is physically at the cable endpoint.

System Integration Benefits

• Deterministic Cycle Time Preservation: Correct bus termination eliminates reflection-induced bit errors that force the PROFIBUS DP master to execute retry cycles. Each retry adds one full bus cycle to the communication latency, degrading the deterministic response time of the control loop. With proper termination, the master operates at its configured minimum cycle time without retry overhead.
• Stable Operation During Partial Shutdown: In multi-zone systems where individual machine sections are powered down independently, the active terminator maintains bus integrity for the remaining active segment — a capability that passive terminators cannot provide when the endpoint device loses power.
• Full Baud Rate Range Without Derating: The terminator is validated across all 12 standard PROFIBUS DP baud rates. No configuration change or hardware substitution is required when upgrading a segment from 1.5 Mbit/s to 12 Mbit/s, reducing commissioning effort during system upgrades.
• Reduced MTTR for Fieldbus Faults: Intermittent bus faults caused by missing or degraded termination are among the most time-consuming to diagnose because they manifest as sporadic communication errors rather than hard faults. Correct installation of the 6ES7972-0DA00-0AA0 eliminates this fault class entirely, reducing mean time to repair for fieldbus-related incidents.
• Compatibility Across SIMATIC Generations: The terminator is compatible with SIMATIC S7-300, S7-400, and S7-1500 CPU modules with onboard DP interfaces, SIMATIC ET 200M/S/SP distributed I/O, SIMATIC NET CP 342-5 and CP 443-5 communication processors, and all SINAMICS and MICROMASTER drive series with PROFIBUS DP option boards.
• Third-Party Master Compatibility: Because the 6ES7972-0DA00-0AA0 operates at the RS-485 physical layer and complies with IEC 61158 / EN 50170, it is fully compatible with PROFIBUS DP masters and slaves from any manufacturer — including ABB, Rockwell, Schneider, and Beckhoff — that use the standard DB9 connector interface.
• Diagnostic Transparency: Proper termination ensures that PROFIBUS DP diagnostic telegrams (DPV1 alarm frames) are transmitted without corruption, allowing the master to receive accurate fault reports from remote I/O stations and drives. Corrupted diagnostic frames caused by poor termination can mask real device faults, delaying corrective action.
• Simplified Segment Extension: When extending an existing PROFIBUS DP segment with a repeater, the active terminator can be relocated to the new segment endpoint without reconfiguration. Its external power supply independence means it functions correctly at any point in the network topology where 24 V DC is available.

Quality Assurance & Global Logistics

Every unit of the Siemens 6ES7972-0DA00-0AA0 supplied by siemensplc.com is sourced through verified supply channels with full traceability to Siemens AG manufacturing. Each component undergoes incoming inspection covering label authenticity verification against Siemens holographic security features, housing integrity assessment, connector pin condition check, and part number cross-reference against the Siemens Industry Mall catalog. Selected batches undergo functional verification on a PROFIBUS DP test bench to confirm correct termination voltage levels and impedance values prior to dispatch.

Packaging follows anti-static and moisture-barrier protocols: each unit is sealed in an ESD-protective bag, placed in a rigid cardboard insert, and shipped in a double-wall corrugated outer carton. For international shipments, a silica gel desiccant pack is included to protect against humidity during transit. A certificate of conformity and commercial invoice with HS code 8538.90 are provided with every shipment to facilitate customs clearance.

Logistics operations are based in Xiamen, China, with direct access to Xiamen Gaoqi International Airport and Xiamen Port for air and sea freight. Standard international shipments are dispatched via DHL Express, FedEx International Priority, or UPS Worldwide Expedited, with typical transit times of 3–5 business days to Europe, 4–6 business days to North America, and 2–4 business days to Southeast Asia. Tracking numbers are provided within 24 hours of dispatch. For urgent requirements, same-day dispatch is available for orders confirmed before 14:00 CST.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.