Configure Redundant Plant Bus Networks in a PCS 7 Multiproject
A PCS 7 multiproject may require merging subnet definitions across its AS and OS subprojects so stations share a project network. This operation is distinct from configuring a redundant physical plant bus. Siemens' PCS 7 V8.1 SP1 fault-tolerant systems manual describes separate Bus1 and Bus2 paths with separate IP ranges; use the release- and hardware-matched topology procedure rather than treating one merged subnet as the complete redundancy configuration.
Table of Contents
- Separate subnet merging from bus redundancy
- Merge project subnets for a shared plant bus
- Design the redundant physical plant bus separately
- Configure and check CP communication
- Verification
- Limitations and Operational Precautions
- Engineer FAQ
- Technical References
- Related Articles
- Related Tags
Separate subnet merging from bus redundancy
A PCS 7 multiproject may contain separate subnet objects in its AS and OS subprojects. Merging those subnet definitions creates a shared cross-project network representation; it is not the same operation as building two physically redundant plant-bus paths. The ticket response correctly distinguishes those tasks, but its suggestion to connect both CPU racks to one subnet is not a complete redundant-bus design.
Merge project subnets for a shared plant bus
Siemens PCS 7 project documentation describes merging subnets in the multiproject so stations in separate subprojects can communicate. In the documented NetPro workflow, open the merge/unmerge subnet dialog, select the matching Ethernet subnets, and add them to the shared global network. Use the exact menu path for the installed PCS 7 version and verify subnet identity/addressing before applying.
Design the redundant physical plant bus separately
The PCS 7 V8.1 SP1 Fault-tolerant Process Control Systems manual shows a redundant fault-tolerant plant bus with two bus paths and specifies different IP address ranges for Bus1 and Bus2. It depicts S7-400H subsystems with CP 443-1 interfaces and calls for checking component redundancy behavior during commissioning. Do not collapse Bus1 and Bus2 into one IP subnet if the documented redundant architecture requires separate ranges.
Configure and check CP communication
The exact CP/CPU and PC-station arrangement determines the number of communication paths. Use the version-matched Fault-tolerant Process Control Systems manual and hardware configuration to assign interfaces, networks, and fault-tolerant connections. Verify each path and failover in a planned commissioning test; a merged subnet in the project does not by itself prove redundant communication.
Verification
Check the multiproject network view to confirm intended subnets are integrated, and inspect each device's assigned interface, IP range, and connection path. During approved commissioning, validate each physical bus independently and confirm failover behavior for supported component faults. Record the as-built topology and address ranges.
Limitations and Operational Precautions
The ticket contains no architecture screenshot, CPU model, CP firmware, OS interfaces, or PCS 7 release. Exact menu paths and supported redundancy topologies vary by release and hardware. Follow the relevant Siemens manual; do not implement the reply's “one subnet” phrase as the complete dual-bus design.
Engineer FAQ
Does merging subnets create a redundant bus? No. It integrates project network objects; physical/network redundancy is a separate design.
How many IP ranges are used in the cited V8.1 SP1 example? Separate ranges for Bus1 and Bus2.
Can each H-system rack use CP 443-1 interfaces? Siemens' cited architecture depicts CP 443-1 interfaces; exact count and connection paths depend on the configuration.
What proves redundancy works? Planned commissioning tests of both paths and supported failover behavior.
Technical References
- Siemens, Fault-tolerant Process Control Systems (V8.1 SP1), section 4.3, “Configuration – redundant, fault-tolerant plant bus,” describes Bus1/Bus2, CP 443-1, separate IP ranges, and commissioning checks: https://cache.industry.siemens.com/dl/files/535/90682535/att_842352/v1/ps7red_b_en-US.pdf
- Siemens, PCS 7 multiproject engineering guide, Entry ID 22258951, section “Generating cross-project networks,” describes merging subnets in NetPro: https://support.industry.siemens.com/cs/attachments/22258951/22258951_DOCU_MP_MU_PCS7_V100_en.pdf