S7-300 Redundant CPU Migration to S7-1500R/H: Engineering Guide

Overview

Migrating a redundant SIMATIC S7-300 configuration based on two CPU 317-2DP controllers and software redundancy (FB101 ZWR_ZYK) to the SIMATIC S7-1500 generation is not a one-to-one substitution. The S7-1500 standard CPU family does not natively support the S7-300 software redundancy model. To preserve the fail-over behavior the client expects when one CPU fails and the standby takes over, the replacement target must be either an S7-1500R (redundant) or an S7-1500H (high-availability, fault-tolerant) CPU. Both families implement redundancy at the firmware level over PROFINET, not PROFIBUS, which has structural consequences for the existing ET 200M remote I/O layer that is currently tied to IM 153-2 PROFIBUS interface modules.

This reference documents the engineering path required to lift an existing S7-300 redundant system — including two CPU 317-2DP, two CP 343-1 communications processors, four ET 200M stations, and the legacy SWR (Software Redundancy) library calls — onto a modern S7-1500R/H platform while reusing as much installed I/O as the budget and the customer's lifecycle targets allow.

Source System Assessment: What You Are Migrating From

CPU and Backplane Hardware

The legacy system consists of two S7-300 stations, each populated with:

• CPU 317-2DP (typical catalog number 6ES7317-2EK14-0AB0 or 6ES7317-2AJ10-0AB0) with integrated DP master and PN/DP interface.
• CP 343-1 (Lean/Standard/Advanced) for the plant Ethernet backbone that the InTouch Wonderware HMI clients connect to.
• PROFIBUS DP segments (typically 1.5 Mbps, MPI/DP universal cable 6XV1830-0EH10) running to four ET 200M stations.

Remote I/O

Four ET 200M remote stations, each equipped with one IM 153-2 (6ES7153-2BA10-0XB0) PROFIBUS interface module and a mixture of SM 321 digital input, SM 322 digital output, SM 331 analog input, and SM 332 analog output signal modules. The IM 153-2 supports PROFIBUS DP-V0/DP-V1 only; it has no PROFINET capability.

Redundancy Implementation

The two CPU 317-2DP stations execute the same user program in master/standby mode. Fail-over is achieved using the Software Redundancy library (SWR) shipped with the STEP 7 add-on package. The principal block is:

• FB101 "ZWR_ZYK" — the cyclic redundancy coordination block. It is called in OB1 (or in OB35 for cyclic exchange) and is responsible for synchronizing process images, copying the data areas between the redundant pair, and detecting a primary failure.
• Companion blocks: FB100 "ZWR_UPDATE" for partner update, FC100 "ZWR_DIAG" for diagnostics, and the relevant data blocks DB WORK, DB SEND, DB RECV.
• Redundancy OBs: OB100 (warm restart), OB102 (cold restart), OB70/OB72 (peripheral / station failure), and OB86 (rack failure).

The redundancy link between the two S7-300 CPUs in this design runs on MPI/PROFIBUS; on the S7-300 the redundancy link must be configured on the same PROFIBUS subnet as the DP master interface.

HMI Layer

Eight operator stations running InTouch Wonderware on Windows XP, polling the two S7-300 stations via Ethernet (CP 343-1, S7 communication, ISO-on-TCP, port 102, TSAP 03.01 / 03.02). The XP platforms are end-of-life and the customer is forced to update them concurrently with the PLC upgrade.

Target Selection: S7-1500 Standard, S7-1500R, or S7-1500H

The S7-1500 family is split into three redundancy-relevant classes. Choosing the wrong one is the single most common migration error.

The redundancy link is implemented entirely on PROFINET in the S7-1500R/H. There is no PROFIBUS-based redundancy on the new platform. This has direct impact on the IM 153-2 migration path, addressed in the next section.

Hardware Migration Path: ET 200M, IM 153, and PROFINET Conversion

Option A — Keep ET 200M, swap IM 153-2 for IM 153-4 PN

The IM 153-4 PN (6ES7153-4BA00-0XB0 or current successor 6ES7153-4BA10-0XB0) is a PROFINET head module for ET 200M. It accepts the same S7-300 signal modules that are already installed in the four remote stations. This option is the lowest-risk, lowest-cost migration: the field wiring, signal modules, and slot layouts remain intact.

• Replace IM 153-2 with IM 153-4 PN at each remote station.
• Connect the IM 153-4 to the S7-1500R/H PROFINET ring via two PROFINET ports (integrated switch).
• Configure the stations as PROFINET IO devices in TIA Portal (HSP / GSDML import).
• Verify that the IM 153-4 firmware is compatible with the planned TIA Portal version (current GSDML for IM 153-4 PN is shipped with TIA Portal V18/V19; confirm against the Siemens Online Support).

Option B — Replace ET 200M with ET 200SP

ET 200SP is the native I/O family for S7-1500R/H and offers the smallest footprint per channel, but it does not accept S7-300 signal modules. BaseUnits (BU type A0/A1) and Head-of-Station (IM 155-6 PN ST, HF, or HS) modules must be specified.

• IM 155-6 PN ST: 6ES7155-6AU00-0BN0 — for standard PROFINET IO.
• IM 155-6 PN HF: 6ES7155-6BU00-0BN0 — supports additional diagnostics, shared device, MRP.
• IM 155-6 PN HS: 6ES7155-6BN00-0CN0 — highest performance, supports PROFIsafe and high-speed applications.
• BaseUnit (type A0): 6ES7193-6BP00-0BA0 (light), 6ES7193-6BP00-0DA0 (dark), 6ES7193-6BP00-0BD0 (potential group start).

Use ET 200SP only when the customer is willing to rewire or when the S7-300 signal modules are obsolete. In a brown-field retrofit, Option A is almost always correct.

PROFINET Network Topology

For an S7-1500R system, configure the two PROFINET ports of each CPU as an MRP (Media Redundancy Protocol) ring. Each ET 200M/IM 153-4 station is a ring node. MRP with a max recovery time of 200 ms is the standard configuration. For S7-1500H, configure MRPD (Media Redundancy with Duplicate frame delivery) on the device-level ring so that on ring break, the duplicate frames guarantee zero-loss fail-over at the device interface.

Software Migration: From FB101 ZWR_ZYK to Firmware Redundancy

Why the SWR Library Cannot Be Ported 1:1

The SWR library blocks (FB100, FB101 "ZWR_ZYK", FC100) were designed for STEP 7 V5.x on S7-300/400. The blocks themselves are not compiled for the S7-1500 controller family. Importing them into TIA Portal will succeed syntactically only if they were originally written in pure STL/SCL without S7-300-specific system functions. In practice, the SWR blocks use:

• SFC 51 (SSL read) — replaced by RD_SINFO or the S7-1500 instruction GetSZL.
• Specific OB semantics for OB70/OB72/OB86 — preserved on S7-1500 but the underlying event IDs differ.
• Direct access to the PROFIBUS address space of the redundancy link — not present on S7-1500R/H.

The correct migration is to remove the SWR block calls and rely entirely on the S7-1500R/H firmware redundancy. The redundancy behavior becomes a property of the CPU configuration in TIA Portal, not of user code. The user's process logic moves verbatim into the OB1 (or the new "ProgramCycle" OB) of the S7-1500R/H without redundancy-specific wrapping.

Migration Steps in TIA Portal

1. Create a new TIA Portal project targeting the S7-1500R or S7-1500H CPU. Confirm that the TIA Portal version supports the selected CPU (TIA Portal V18 or later is recommended; refer to the Siemens "Function Manual: S7-1500R/H redundant system" entry ID 109754833).
2. Open the source STEP 7 V5.x project and use TIA Portal > Project > Migrate project. The S7-300 blocks, HW config, and the user program are translated automatically.
3. During migration, the IM 153-2 PROFIBUS stations are converted to a representation that TIA Portal can rewrite. You will need to manually re-assign them as PROFINET IO devices using the IM 153-4 PN GSDML.
4. Delete the SWR library blocks (FB100, FB101 "ZWR_ZYK", FC100) and their instance DBs. Replace each call in OB1 with the bare user logic. Configure redundancy at the CPU level instead.
5. Re-compile, perform consistency check, and download to the CPU pair.

Communications Processor Migration: Replacing CP 343-1

The S7-1500R/H CPUs integrate PROFINET interfaces that support S7 communication and ISO-on-TCP (now "TCP/IP (RFC1006)" / TCON). A separate CP 1500 or CP 1543-1 communications processor is required only when the application needs:

• Extra PROFINET ports (CM 1542-1: 6GK7542-1AX00-0XE0, CP 1543-1: 6GK7543-1AX00-0XE0).
• Open User Communication (OUC) with TCP/UDP as well as S7 routing.
• IPsec / firewall / VPN (CP 1543SP-1: 6GK7543-1WX00-0XE0, or the CP 1545-1: 6GK7545-1GX00-0XE0).

If the InTouch Wonderware clients connect via SuiteLink/OPC, plan an OPC UA server in TIA Portal using the OPC UA Server functionality of the S7-1500R/H (firmware 2.8 and later). This allows retirement of the OPC Link/KEPServerEX middleware if desired.

HMI Modernization Path: Wonderware on Windows XP → Modern Operator System

Windows XP and InTouch 2012 (and earlier) are unsupported by Aveva (formerly Wonderware). Two viable replacement paths exist for the eight operator stations:

For the lowest integration risk with the S7-1500R/H, install the SIMATIC WinCC Unified PC Runtime (6AV2155-... ) and configure the native S7-1500 driver. This removes the Wonderware OPC interface as a single point of failure and lets the HMI panel directly browse the controller's OPC UA namespace.

Step-by-Step Migration Procedure (Recommended Sequence)

1. Audit the legacy project. Export the STEP 7 V5.x archive and inventory all SWR library calls. Confirm whether fail-over was bumpless or non-bumpless; this decision drives the choice of S7-1500R vs S7-1500H.
2. Run the TIA Selection Tool (https://www.siemens.com/tia-selection-tool) to compile the candidate bill of materials: CPU pair, IM 153-4 PN head modules, PROFINET switches (managed, e.g. SCALANCE XC/XR series), and any required CP modules.
3. Build the TIA Portal project. Insert the CPU pair, configure the PROFINET ring, assign ET 200M stations as IO devices.
4. Migrate the user program from STEP 7 V5.x to TIA Portal. Use the migration guide at 109478811 as the authoritative reference.
5. Remove SWR blocks. Replace FB101 "ZWR_ZYK" calls with the unobstructed process logic. Configure firmware redundancy in the device configuration.
6. Configure HMI. Build the WinCC Unified project (or InTouch upgrade project) and validate against the live controller in PLCSIM or on a single-CPU bench.
7. Factory acceptance test (FAT) in a staging area with both CPUs, full PROFINET ring, and simulated I/O.
8. Site cutover during a planned shutdown. Replace S7-300 stations with S7-1500R/H pair, replace IM 153-2 with IM 153-4 PN at each ET 200M, switch over Wonderware panels or boot WinCC Unified Runtime.
9. Commissioning and validation. Perform forced fail-over by removing the primary CPU's PROFINET sync link and verify that outputs maintain the last value (S7-1500H) or accept the short controlled loss (S7-1500R).

Verification and Acceptance Tests

After download, run the following verifications on the new S7-1500R/H system:

• Topology check: TIA Portal → Online → Topology view shows all PROFINET ports connected as expected, and the redundancy ring ports are correctly assigned.
• Diagnostic buffer: Both CPUs should report a clean redundancy status (primary/backup) without transient sync errors. Read the redundant system diagnostic buffer at the S7-1500R/H panel.
• Forced fail-over: Disconnect the PROFINET sync cable from the primary CPU. S7-1500H should keep outputs unchanged; S7-1500R should perform a controlled restart of the standby and resume.
• OB70/OB72 non-execution on H: Verify that the user program runs through the fail-over without entering OB70 (loss of redundancy) on the standby. OB70 entry on the primary is acceptable; OB70 on the standby is a wiring/timing error.
• HMI connectivity: Confirm that all eight HMI stations maintain connectivity with the active CPU. In S7 communication, the active CPU responds on TSAP 03.01; the standby is reachable only via the partner TSAP.

Troubleshooting Matrix

Field-Commissioning Notes and Edge Cases

• The two PROFINET ports of an S7-1500R CPU are fixed as PROFINET ring ports and PROFINET system ring ports respectively. Do not connect the HMI to the ring ports; use the integrated switch in a SCALANCE X-managed switch instead.
• For S7-1500H, the SYNC150x fiber modules (SYNC150-1 6ES7658-1AX00-0AA0, SYNC150-2 6ES7658-1BX00-0AA0) are mandatory for the redundancy link. They are not included with the CPU and must be ordered separately.
• If the customer requires SIL2 / IEC 61508 safety, the S7-1500R/H does not support PROFIsafe as a redundancy pair in the way the S7-300F did. A SIMATIC S7-1500F standard CPU, or a separate safety PLC, must be evaluated.
• When migrating, the S7-300 signal modules retain their GSD descriptions in TIA Portal V18/V19; however, support for some legacy SM 300 modules was migrated to "S7-300/S7-400 to S7-1500 HMI Migration" notes — verify each SM 3xx by its catalog number against the current SP list.
• The S7-300 redundant systems relied on timing windows configured via the SWR library (e.g., SWR_ZYK_TIME). With firmware redundancy, the cycle time and fail-over time are properties of the PROFINET ring configuration. Document them as system properties in the customer's maintenance procedures.
• For plants with existing PROFIBUS DP subnets (e.g., drives, valve actuators), retain them behind an IE/PB Link PN IO (6GK1411-2AB10) or connect via PROFIBUS masters that the new S7-1500R/H CPU exposes through a CP/CM module. The CPU 1515R-2 PN has no integrated PROFIBUS interface.

Documentation to File With the Migration Package

• Migration Guide: SIMATIC S7-300/400 to SIMATIC S7-1500 — Siemens Support entry 109478811.
• Function Manual: S7-1500R/H redundant system — Siemens Support entry 109754833.
• S7 Software Redundancy System Manual (legacy) — SWR manual (PDF) for audit purposes only.
• TIA Portal release notes for the firmware of the selected S7-1500R/H CPU (e.g., firmware V3.1 supports redundancy OBs with expanded diagnostics).
• TIA Selection Tool export as the BOM baseline.

Frequently Asked Questions