SIMATIC OPC UA · primary-source review 25 July 2026
Siemens OPC UA: S7-1200/1500 Setup, Licence & Limits
For the classic S7-1200 family, Siemens documents an OPC UA server from firmware V4.4 configured with TIA Portal V16 or later. The S7-1500 server starts from firmware V2.0, while its OPC UA client starts from V2.6. A runtime licence is required per CPU, and the exact licence capacity, TIA release and CPU system limits must be selected from current Siemens documentation.
Important generation boundary: Siemens’ S7-1200 G2 migration guide states that OPC UA is not supported for S7-1200 G2 in TIA Portal V20. Do not treat “S7-1200” as one timeless compatibility claim.
Compatibility and licensing matrix
These are starting boundaries, not a substitute for the manual for the exact CPU order number. Some features require later firmware or TIA versions than the minimum line below.
| CPU family | Role | Minimum documented boundary | Licence / decision note |
|---|---|---|---|
| S7-1200 (classic family) | OPC UA server | CPU firmware V4.4; configure from TIA Portal V16 | A CPU runtime licence is required. Select the current S7-1200 OPC UA licence article for the exact CPU and delivery model. |
| S7-1500 | OPC UA server | CPU firmware V2.0; configure from TIA Portal V14 | A CPU runtime licence is required. Capacity and the purchased licence tier must match the exact CPU and planned server load. |
| S7-1500 | OPC UA client | CPU firmware V2.6; configure from TIA Portal V15.1 | Verify the current CPU and OPC UA option documentation; server availability does not by itself prove client support. |
| S7-1200 G2 | Do not infer from classic S7-1200 | Siemens’ current migration guide states OPC UA is not supported for S7-1200 G2 in TIA Portal V20 | Check the current G2 system manual and TIA release before designing around OPC UA. |
Configuration path that preserves the evidence
- 1Identify the CPU order number, generation and firmware. Verify server or client support in that CPU’s current communication manual.
- 2Choose a TIA Portal release that supports the CPU, firmware and required OPC UA feature; archive the installer and project version.
- 3Purchase and assign the correct one-CPU OPC UA runtime licence. Keep the licence certificate and article number with the asset record.
- 4Enable the CPU OPC UA role, define the server endpoint and export only the required PLC variables or modelled interface.
- 5Create named users and the least privileges the client needs. Disable anonymous access when the security requirement forbids it.
- 6Generate or import certificates, document trust ownership, and select the strongest security policy supported by every approved endpoint.
- 7Connect a test client, browse the intended namespace, create subscriptions, write only to approved test nodes and capture quality and timestamps.
- 8Measure CPU communications load and recovery under the planned sessions, subscriptions, monitored items and publishing intervals.
- 9Export the project, certificates and client settings; execute the loss-of-network, replacement, restore and rollback tests before production use.
Proof-of-fit acceptance tests
Certificate trust
The client trusts the PLC certificate, the PLC trusts the required client certificate, and an untrusted certificate is rejected.
Identity and permissions
Anonymous access is disabled when the requirement forbids it; each test user can read or write only the intended nodes.
Namespace stability
Every consumed tag uses a documented namespace and NodeId strategy that survives an approved project download or is remapped under change control.
Subscription recovery
The client detects loss, reconnects, recreates subscriptions and reports data quality without silently presenting stale values.
Load boundary
Measured CPU communications load, publishing intervals, sessions, subscriptions and monitored items remain inside the exact CPU manual limits.
Backup and restore
The TIA project, licence certificate, endpoint settings, certificates and client configuration can be restored on the documented replacement path.
Limits that must come from the exact CPU manual
- • Maximum sessions, subscriptions, monitored items and user accounts.
- • Supported services, methods, companion specifications and information-model features.
- • Security policies, certificate handling and permitted identity modes.
- • Communications load, sampling and publishing behavior under the real cycle-time requirement.
- • Online-change, project-download and NodeId stability for the engineered model.
- • Redundancy, safety, failover and replacement behavior for the selected controller architecture.
Related training product
Practise the Siemens-style control logic separately
PLC Simulation Software can be used to practise Siemens-style timers, interlocks, sequences and communications-loss supervision in a browser. It is not an S7 OPC UA server or client, does not emulate SIMATIC firmware, and cannot validate certificates, licences, NodeIds or CPU communications limits.
Try Siemens-style PLC practiceOwnership disclosure: PLC Programming IO and PLC Simulation Software share ownership. Use TIA Portal, the licensed CPU and a real OPC UA client for implementation evidence.
Primary sources
Current controller communication scope, including S7-1200 server availability from firmware V4.4 and S7-1500 client availability from firmware V2.6.
A complete S7-1200 V4.4 and TIA Portal V16 application example, including information-model and client-test workflow.
An active one-CPU S7-1200 OPC UA server runtime-licence article and its current catalogue boundary.
The documented S7-1200 G2 limitation in TIA Portal V20; classic S7-1200 OPC UA assumptions must not be copied to G2.
Normative OPC UA service, information-model, security and transport references. Siemens manuals remain authoritative for CPU implementation limits.