SINAMICS S120 OPC Communication: SIMATIC NET PC Station Setup

Overview

The SINAMICS S120 drive family exposes its process data (control words, setpoints, status words, actual values) through a deterministic telegram interface. To make this data available to HMI, SCADA, or higher-level MES applications, the most common integration path is a SIMATIC NET PC station acting as an OPC DA / OPC UA server on a standard industrial Ethernet (PROFINET) network. The PC station reads the cyclic process image from the SINAMICS Control Unit (CU310PN, CU310-2 PN, or CU320-2 PN) and re-publishes the values as OPC tags that any OPC client can subscribe to.

Engineers new to this architecture often ask three concrete questions:

1. Can a regular on-board PC Ethernet port be used, or is a Siemens CP1616 / CP1623 required?
2. What SINAMICS Control Unit (CU) is mandatory for PROFINET-based OPC access?
3. Why are the data-block addresses DBW2048 and DBW3072 offset by exactly 1024 bytes, and how do I extend the pattern to 1, 3, 4, or more axes?

This reference answers those questions with the parameter-level detail required for commissioning, including the exact telegram types, slot layout, and OPC tag mapping recommended in the Siemens documentation Accessing SINAMICS parameters via OPC server (SIMATIC NET, V8.x, PDF).

System Architecture

The architecture has three logical tiers: the SINAMICS drive line, the PROFINET/Ethernet transport, and the OPC client tier. The SIMATIC NET PC software sits on the transport tier as both an OPC server and an IE/PROFINET node.

Prerequisites

Control Unit Selection for OPC Communication

OPC over Ethernet is only possible if the SINAMICS Control Unit has an Ethernet / PROFINET interface that the SIMATIC NET PC can reach on IP. The available CUs and their OPC compatibility are summarized below.

For the configuration shown in the source material (one PC station talking to two Servo drive objects), the most common hardware choices are:

• CU310PN × 2, each on its own PROFINET device name (one axis per CU), or
• CU320-2 PN with two Motor Modules, exposing Servo_02 and Servo_03 as Drive Objects (DO2 and DO3) on a single PROFINET node.

PC Station Configuration in SIMATIC NET

Use the Station Configuration Editor that ships with SIMATIC NET to assemble the PC station before any OPC tags are created. The configuration is stored in the PC station's XML, not the project, and it is consumed by the runtime service SIMATIC NET Configuration Service.

1. Open Station Configuration Editor (Start » Siemens Automation » SIMATIC » SIMATIC NET » Configuration Console).
2. Add an OPC server slot: select OPC Server from the catalog and drag it into slot 1.
3. Add an IE / PROFINET interface: select IE from the catalog and assign it to the physical NIC (on-board or CP1616). The slot number is typically 0 for the IE module.
4. Assign the PC station an IP address that is reachable from the SINAMICS CUs (subnet must match PN-IO subnet).
5. Save, then click Station » Load so the runtime loads the configuration. The OPC DA server OPC.SimaticNET starts once the configuration loads.
6. Verify the OPC server is registered. From an elevated command prompt:

   opcenum -list
   

   The list must contain OPC.SimaticNET. If it does not, restart the service:

   net stop "SIMATIC NET Configuration Service"
   net start "SIMATIC NET Configuration Service"
   

SINAMICS S120 Telegram Configuration

The cyclic process image is defined by the telegram type. Each drive object uses one telegram. The default telegram and the data word length (PZD) are configured by parameters on the drive object.

For each additional Drive Object, the telegram is selected via p0922 on that DO, and a list of telegrams is set globally with p2079. The DO mapping in the PROFINET telegram is defined by p0978 (subslot 0 for the CU, subslots 1..n for DOs).

Data Block Mapping and Offset Explanation

The source material references two data blocks with addresses that look unfamiliar at first:

• DB2098.DBW2048 — Control word 1 (ON/OFF1), Servo_02
• DB1001.DBD2048 — Setpoint (REAL, NSOLL), Servo_02
• DB898.DBW2048 — Status word (WORD), Servo_02
• DB63.DBD2048 — Actual speed (REAL, NIST_A), Servo_02

And for Servo_03, the addresses are uniformly offset by 1024 bytes (0x400):

• DB2098.DBW3072 (= 2048 + 1024)
• DB1001.DBD3072
• DB898.DBW3072
• DB63.DBD3072

Three things are happening at once and they all need to be understood separately.

Why the same address for different data types

The same numeric address appears four times because each DB holds a different word of the process image for the same axis slot. They are not the same memory location. The DB number identifies which field of the telegram is being read:

The exact DB numbers (DB 2098, DB 1001, DB 898, DB 63) are project-specific. They are assigned when the OPC server wizard maps the PROFINET slots to S7-compatible data blocks. As long as the wizard has access to the same drive configuration, the DB numbers are deterministic for a given project.

Why byte offset 2048 and 3072

The SINAMICS S120 reserves a 1024-byte (0x400) slot per Drive Object in the PROFINET process image. The base offset of 2048 (0x800) is the configured I/O base address of the SINAMICS station as entered in STEP 7 / TIA on the PC station, or the start of the S7 input/output area assigned to the IE module. Drive Object 2 (Servo_02) starts at byte 2048, and Drive Object 3 (Servo_03) starts at 2048 + 1024 = 3072.

Extending the pattern to 1, 3, 4 axes

For an arbitrary number of axes, the rule is simple:

offset(DO_n) = base_offset + (n - 2) * 1024     [bytes, decimal]
offset_hex(DO_n) = base_offset_hex + (n - 2) * 0x400

Applied to the project:

For six axes on a CU320-2 PN with CBE20, the highest slot is at 2048 + 5 * 1024 = 7168 (0x1C00). The reserved base area of 2048 bytes (slots 0) is always present, and on a CU320-2 with CBE20 the limit is six Drive Objects per PROFINET interface.

Step-by-Step Commissioning

1. Assign the PROFINET device name to the CU310PN / CU320-2 PN from STARTER / Startdrive using Topology Editor or PRONETA. Without a unique PROFINET name, the SIMATIC NET PC station will not establish AR (Application Relationship).
2. Configure the telegram in STARTER: in the drive's Communication node, select telegram (e.g., 3 for 32-bit speed). For CU320-2 PN, also configure p0978 with the list of DOs to be mapped cyclically.
3. Build the PC station in STEP 7 / TIA Portal: drag a PC station into the project, add an OPC server and an IE module, and assign the IE module to the same PROFINET subnet as the SINAMICS station.
4. Download the PC station configuration via the Station Configuration Editor (live) or via the project download (offline). Confirm the IE module shows running in the Configuration Console.
5. Establish cyclic communication: from the OPC Scout V10 (bundled with SIMATIC NET), browse the OPC DA namespace OPC.SimaticNET → the S7 connection. The four DBs (control, setpoint, status, actual) must be visible.
6. Write a test value to verify write access. From OPC Scout, write to DB2098.DBW2048 a value of 0x047E (control word: ON + OFF1 + OFF2 cleared + enable). The drive should accept the command and the status word DB898.DBW2048 should transition to 0x0531 or similar.
7. Subscribe the OPC client (WinCC, TIA HMI, or third-party) to the same tags at a 100 ms update rate. Cyclic PROFINET updates at 1 ms (or the configured send clock) feed the OPC cache.

Verification and Diagnostics

Once the OPC server is running, verify each layer independently.

1. PROFINET link: the IE module in the Configuration Console must show operate and no errors. The SINAMICS station's PROFINET LEDs (PN 1 / PN 2) must be solid green on the port connected to the switch.
2. Cyclic I/O: in STARTER online mode, open Control » Commissioning » Telegram diagnostics and confirm the receive / send PZD counters increment. A non-incrementing counter indicates configuration mismatch (e.g., telegram type wrong on one side).
3. OPC DA browsing: in OPC Scout, browse OPC.SimaticNET. The tags must appear with current quality Good (0xC0). If the quality is Bad (0x00) or Uncertain (0x40), check the S7 connection in NetPro / TIA.
4. OPC UA (if used): if you switched to OPC UA, the endpoint is opc.tcp://<PC>:48010 and the security policies are None, Basic128Rsa15, or Basic256Sha256. The certificate must be trusted in the client's certificate store.
5. Status word walk: write control word 0x047E, then 0x047F. Status word must transition 0x0531 → 0x0537 → 0x053F within one PROFINET update cycle.

Troubleshooting Matrix

Frequently Asked Questions