Siemens 6ES7972-0BB42-0XA0 Replacement/Upgrade Solution for S7

Product Overview

Siemens 6ES7972-0BB42-0XA0 Replacement/Upgrade Solution for S7: Smooth Transition from Legacy PROFIBUS Systems

The Siemens 6ES7972-0BB42-0XA0 is a 90° Sub-D9 PROFIBUS DP bus connector designed for use across the SIMATIC S7 platform, including S7-300 and S7-400 series controllers. As industrial facilities phase out aging fieldbus infrastructure or replace worn connectors on legacy lines, this component serves as a direct, pin-compatible replacement that requires no rewiring, no firmware changes, and no modification to existing PROFIBUS segment topology.

For plants running older PROFIBUS DP networks — whether connected to a CPU 315-2 DP, CPU 414-2 DP, or distributed I/O via ET 200M or ET 200S remote I/O stations — the 6ES7972-0BB42-0XA0 slots directly into the existing Sub-D9 port without any segment reconfiguration. The 90° cable exit angle is specifically suited for installations where panel depth is limited or where cable routing runs parallel to the DIN rail, making it a preferred choice for compact control cabinet retrofits.

Compatibility Comparison Table

Seamless Upgrade Solutions

A PROFIBUS DP connector replacement rarely happens in isolation. During a planned maintenance window or an unplanned line stoppage, engineers typically audit the entire fieldbus segment. In practice, the 6ES7972-0BB42-0XA0 is most often replaced or upgraded alongside related components that share the same rack, cabinet, or DP segment.

On the controller side, facilities migrating from an aging CPU 315-2 DP (6ES7315-2AH14-0AB0) to a newer CPU 1515-2 PN/DP will find that the PROFIBUS DP interface on the new CPU accepts the same Sub-D9 connector format, preserving the existing field wiring. Where the legacy system used a CP 342-5 communications processor to offload PROFIBUS DP master tasks from the CPU, the same connector standard applies, and no cable changes are needed at the field device end.

For distributed I/O nodes, ET 200M interface modules (IM 153-2) and ET 200S interface modules (IM 151-1) both use the same PROFIBUS DP Sub-D9 bus connector. Replacing connectors at these nodes during a retrofit ensures the entire segment benefits from consistent termination quality and reduces the risk of intermittent communication faults caused by degraded legacy connectors.

Power supply integrity is equally critical during a migration. The PS 307 (6ES7307-1EA01-0AA0) 24 VDC power supply module, commonly installed in S7-300 racks, should be inspected and replaced if it has exceeded its service life, as power rail instability is a leading cause of PROFIBUS communication errors that are often misdiagnosed as connector faults. Similarly, the SM 321 digital input module and SM 322 digital output module in the same rack should be verified for firmware compatibility when upgrading the CPU.

For sites that require programming access during commissioning without interrupting the live PROFIBUS segment, the integrated PG/PC pass-through port on the 6ES7972-0BB42-0XA0 allows a PC Adapter USB A2 (6ES7972-0CB20-0XA0) to be connected directly to the connector without breaking the bus. This eliminates the need for a separate tap or segment splitter during on-site debugging.

Where the legacy system includes a SIMATIC HMI TP700 Comfort or OP 177B panel connected via PROFIBUS DP, the connector replacement is transparent to the HMI — no project download or communication parameter change is required, provided the bus address and baud rate remain unchanged.

Retrofit Guidance FAQ

Q: Does replacing the 6ES7972-0BB42-0XA0 require re-terminating the PROFIBUS segment?
A: No. The connector includes an integrated switchable bus termination resistor. Simply match the termination switch position (ON for segment-end nodes, OFF for intermediate nodes) to the original connector setting. No segment reconfiguration or baud rate change is required.

Q: Is the wiring pinout identical to older PROFIBUS DP connectors?
A: Yes. The Sub-D9 pinout follows the IEC 61158 / EN 50170 PROFIBUS standard. Pin A (green) and Pin B (red) assignments are identical across all standard PROFIBUS DP connectors. Existing field cables can be transferred directly to the new connector without modification.

Q: Can this connector be used on an S7-1500 CPU with a PROFIBUS DP interface?
A: Yes. The S7-1500 CPUs equipped with a DP interface (e.g., CPU 1515-2 PN/DP) use the same Sub-D9 PROFIBUS DP port. The 6ES7972-0BB42-0XA0 is fully compatible.

Q: What is the maximum supported baud rate?
A: Up to 12 Mbit/s, covering all standard PROFIBUS DP baud rates from 9.6 kbit/s to 12 Mbit/s.

Q: Will the 90° cable exit cause any physical clearance issues in a standard S7-300 rack?
A: The 90° exit is designed for installations where horizontal cable routing is required. It reduces the depth footprint compared to a straight connector and is suitable for most standard control cabinet configurations. Verify the available lateral clearance (minimum 40 mm recommended) before installation.

Warranty Assurance

Every 6ES7972-0BB42-0XA0 unit shipped by TOPNLMS is covered by a 12-month warranty from the date of delivery. Prior to dispatch, each unit undergoes visual inspection and functional verification to confirm connector integrity, termination switch operation, and PG/PC port continuity. Units that do not pass inspection are not shipped.

In the event of a confirmed defect within the warranty period, TOPNLMS provides direct replacement support. Our response target for warranty claims is within 2 business days of receipt of the defective unit. Replacement units are dispatched from our Xiamen warehouse, with express shipping options available for urgent production line requirements.

Stock is maintained on-hand for immediate dispatch. Standard lead time is 1–3 business days for in-stock items. For bulk procurement or project-based orders requiring multiple connectors across a PROFIBUS segment upgrade, volume pricing and consolidated shipping are available upon request.

For procurement inquiries, technical compatibility questions, or warranty claims, contact our industrial automation team directly.