SIMATIC S7-1500

What you can build

• Turn an alarm flood into one ranked list

  Subscribe to Alarms and Conditions events from the CPU, group bursts by source and cause, and propose which alarms deserve a person first.

  With Alarm Flood

• Account for OEE losses from DB counters

  Read good, reject, and cycle counters from a production data block, attribute lost minutes to machine states, and draft the loss ledger for review.

  With OEE Loss

• Catch a batch drifting from its recipe

  Observe recipe setpoints and measured values in a batch DB, compare each step against its limits, and raise a deviation for approval.

  With Batch Deviation

• Propose a method call instead of a raw write

  Where the PLC program exposes a server method, propose the call with its arguments and record the result the CPU returns.

  With Changeover Plan

Requirements

• An S7-1500 CPU at firmware V2.0 or later with its OPC UA server enabled under "OPC UA > Server"; it is off by default
• A SIMATIC OPC UA S7-1500 runtime license sized to the CPU: small, medium, or large
• Tags and DB components marked "Accessible from HMI/OPC UA", and "Writable from HMI/OPC UA" for anything the operator may propose to write
• A user holding the "OPC UA server access" function right (firmware V3.1 and later), or an entry in the CPU's user management on earlier firmware
• Client and server certificates the CPU trusts, and a correct date and time on the CPU so certificates validate

Authentication

OPC UA user name and password authentication over a secure channel (Sign or SignAndEncrypt, Basic256Sha256 where the client supports it), with X.509 certificates exchanged between the client and the CPU; guest (anonymous) access can be switched off.

Limits

• The server is not reachable through CP or CM modules over the backplane bus; connect through the CPU's own Ethernet interfaces
• Up to firmware V3.0 the CPU's user management holds a maximum of 21 users
• Removing rights from one component of a structure or DB stops the whole structure being read or written in one pass
• The maximum number of monitored items depends on the CPU, and the server sends notifications no faster than its minimum publishing interval

Questions and answers

Is the OPC UA server on by default?

No. For security the server is disabled until you activate it under "OPC UA > Server" in the CPU properties, confirm the security notes, set the runtime license, compile, and download the project. OPC UA clients have neither read nor write access until then.

Which security policies and authentication does the S7-1500 server offer?

Endpoints combine a Message Security Mode of None, Sign, or SignAndEncrypt with a Security Policy of None, Basic128Rsa15, Basic256, or Basic256Sha256. Users authenticate as guest (anonymous) or with user name and password, carried under a UserTokenPolicy that encrypts credentials even when the channel itself is unsecured.

How do I keep a tag out of the connector's reach?

Clear "Accessible from HMI/OPC UA" on the tag and the server removes it from its address space. Clear only "Writable from HMI/OPC UA" to leave it read-only. A central setting can also block an entire data block, overriding the per-component settings.