---
title: Testing a Siemens S7 connection
slug: how-tos/9gKi-testing-a-siemens
docTags: w56nvEoTA2xAb2x1X3JPc
createdAt: 2025-09-24T11:54:08.157Z
---

## Step 1: Install a Siemens S7 client (Explorer/Tester)

To connect and browse a Siemens S7 PLC, you’ll need a tool that can communicate via the **S7 protocol (ISO-on-TCP / RFC1006)**. Siemens provides several official tools, and there are also some reliable third-party options.

| Client Name                | Platforms      | Link                                                                                                                    |
| -------------------------- | -------------- | ----------------------------------------------------------------------------------------------------------------------- |
| Siemens TIA Portal (Trial) | Windows        | [Download](https://www.siemens.com/global/en/products/automation/industry-software/automation-software/tia-portal.html) |
| S7‑Project‑Explorer        | .NET (Windows) | [Download](https://github.com/enlyze/S7-Project-Explorer?tab=readme-ov-file)                                            |

## Step 2: Gather connection details

To connect to the S7 PLC, you’ll need the following information:

- **PLC IP Address:** The Ethernet IP of the PLC or device (e.g. `192.168.0.10`)
- **Rack and Slot:** The internal hardware configuration.
   Common values:
  - S7-300: Rack `0`, Slot `2`
  - S7-400: Rack `0`, Slot `3`
  - S7-1200/1500: Rack `0`, Slot `1`
- **Connection Type:** Usually `S7 connection (ISO on TCP)`, port `102`
- **Security / Authentication:**
  - Older S7-300/400 models often have **no authentication**.
  - Newer S7-1200/1500 may require **user credentials** and **TLS encryption**, depending on project settings.
- **CPU Access Protection:** Check if “Full access” or “Read access” is enabled in TIA Portal under *Protection & Security.*

:::hint{type="info"}
If your connection is refused, the PLC may have **"Connection Mechanism Only with Known Partners"** enabled. Disable it temporarily in TIA Portal to test connections from new clients.
:::

## Step 3: Test and browse data blocks

Once the connection parameters are correct, you can:

- Read diagnostic information (RUN/STOP state, cycle time, etc.)
- Browse **Data Blocks (DBs)**, **Inputs/Outputs (I/Q)**, and **Memory (M)** areas.
- Test read/write access to verify connectivity.