Configuring CP 343-1 Communication with WinCC 7.2 on Windows 7

Overview

The Siemens CP 343-1 communication processor is the standard Industrial Ethernet interface for the S7-300 PLC family. It provides the physical and logical layer required to exchange process data, alarms, and diagnostics between a SIMATIC S7-300 station and a higher-level HMI/SCADA host such as SIMATIC WinCC V7.2 running on Windows 7 64-bit. Communication is established using either the TCP/IP channel unit or the Industrial Ethernet channel unit of the WinCC S7 Protocol Suite. The choice between the two depends on whether the WinCC station uses a standard network interface card (NIC) or a Siemens Hardnet module (CP 5613 / CP 5614), which in turn dictates the SIMATIC NET license required.

This article consolidates the field-proven sequence for bringing a CP 343-1 online with WinCC V7.2, including Windows 7 64-bit prerequisites, NCM S7 CP configuration, SIMATIC NET licensing decisions, the WinCC S7 Protocol Suite channel setup, and the diagnostic workflow that resolves the most common connection faults.

Prerequisites

Before commissioning the CP 343-1 to WinCC link, verify the following items on the engineering station, the PLC rack, and the network that connects them.

1. Engineering software installed on the WinCC station:
   • STEP 7 V5.5 (or compatible) including NCM S7 for Industrial Ethernet — required to download the CP 343-1 hardware configuration and the connection data.
   • SIMATIC WinCC V7.2 SP3 (or later) with the 32-bit S7 Protocol Suite installed.
   • SIMATIC NET V8.x or V12 — required for the S7OPC / S7 Protocol Suite drivers. Install the 32-bit SIMATIC NET on a 64-bit Windows 7 OS because WinCC V7.2 is a 32-bit application.
2. PLC hardware:
   • SIMATIC S7-300 with a CP 343-1 mounted in the central rack. The CP occupies a slot in the S7-300 backplane and is configured as a CP, not as an I/O module.
   • Power supply, CPU (any S7-300 CPU that supports the CP), and the CP 343-1 module.
3. Network:
   • Ethernet switch (managed or unmanaged) using 10/100 Mbit/s; gigabit is supported by newer CP 343-1 variants.
   • Patch cables terminated RJ45; the CP 343-1 has an 8-pin RJ45 socket for the ITP/Industrial Ethernet LAN.
   • A unique IP address and subnet mask for the CP, in the same subnet as the WinCC station's NIC.
4. User rights: Local administrator rights on the WinCC PC for installing the S7 Protocol Suite, configuring the PC interface, and starting/stopping the S7DOS service.

CP 343-1 Hardware Identification and Capabilities

Several CP 343-1 variants have been produced. Identify the MLFB (order number) printed on the front of the module before commissioning, because firmware and protocol support differ between revisions.

Refer to the CP 343-1 manual (PDF) for the full module description, the LED diagnostic table, and the exact configuration options. The manual's chapter 1 covers initialization of the CP for communication services using NCM S7 for Industrial Ethernet.

Windows 7 64-bit Compatibility Matrix for WinCC V7.2

Communication Architecture and Protocol Selection

WinCC V7.2 communicates with the S7-300 over the S7 Protocol Suite. Within the S7 Protocol Suite the user selects one of the following channel units per logical connection:

For most Windows 7 64-bit + standard NIC installations, the TCP/IP channel unit is the recommended path. The chapter 11.5.3.8 "TCP/IP" channel unit of the WinCC V7.2 Communication manual covers the configuration. For installations with a Siemens Hardnet module (CP 5613 / CP 5614) the Industrial Ethernet (I+II) channel unit is documented in chapter 11.5.3.2 of the same manual.

Step 1 — Configure the CP 343-1 in HW Config

1. Open SIMATIC Manager with the STEP 7 project that contains the S7-300 station.
2. Open HW Config for the S7-300 station.
3. From the hardware catalog, insert the CP 343-1 matching the order number on the front of the module. Position it in a free slot of the central rack.
4. Double-click the CP to open its Properties — CP 343-1 dialog.
   • Assign an IP address and subnet mask that belong to the same subnet as the WinCC station.
   • Enable the S7 communication service (default on most variants). If the S7 connection will be used for PUT/GET from peer CPUs, leave the S7 function active.
   • Set the CP to RUN as a startup option.
5. Save and compile the hardware configuration, then download the HW Config to the CPU and CP. The CP's LINK LED must come on solid green after the download.

Step 2 — Define the S7 Connection in NetPro

The WinCC station must be added to the STEP 7 project as a "SIMATIC PC Station" and a logical S7 connection must be defined in NetPro. The connection target is the S7-300 CPU, not the CP itself, but the connection traverses the CP 343-1.

1. In NetPro, right-click the SIMATIC PC Station and select Insert New Connection.
2. Choose the S7-300 CPU as the partner.
3. Set the connection type to S7 connection.
4. Confirm the local interface is the IE interface of the PC station (this is the placeholder for the S7 Protocol Suite / standard NIC in the WinCC runtime).
5. Save and compile NetPro, then download the configuration to the PC station's "PC internal" target.

Step 3 — Install and License SIMATIC NET

SIMATIC NET provides the S7 driver layer that the WinCC S7 Protocol Suite uses. The license level depends on the PC hardware.

If STEP 7 is installed on the same PC as WinCC, the Softnet drivers for the standard NIC are already installed as part of STEP 7. If STEP 7 is not installed on the WinCC station, the WinCC V7.2 DVD includes an IE-Softnet Lean license that will support the standard NIC. Insert the DVD and run the SIMATIC NET setup with the "IE Softnet Lean" option enabled.

Step 4 — Configure the Access Point and PG/PC Interface

The Set PG/PC Interface tool (part of STEP 7 / SIMATIC NET) defines which access point maps to which physical or logical network adapter. This is the most common source of "connection cannot be established" faults.

1. Open Set PG/PC Interface (Start → SIMATIC → SIMATIC NET → Set PG-PC Interface, or via Control Panel).
2. For the S7ONLINE access point, select the access that matches the channel unit chosen in WinCC:
   • For the TCP/IP channel unit → TCP/IP -> <NetworkCardName> (e.g. "TCP/IP -> Intel(R) 82579V Gigabit").
   • For the Industrial Ethernet channel unit with a Softnet path → IE Softnet -> <NetworkCardName>.
   • For the Industrial Ethernet channel unit with a Hardnet module → CP 5613/CP 5614 (or CP 1613/CP 1623).
3. Click Diagnostics to confirm that the selected module is reachable. The diagnostic window reports the local MAC, the configured IP, and any error counters on the interface.

Step 5 — Add the S7 Protocol Suite Channel in WinCC Explorer

1. Open WinCC Explorer and load the project in Configuration mode.
2. Right-click Tag Management → Add New Driver → select S7 Protocol Suite → TCP/IP (or Industrial Ethernet) channel unit.
3. Right-click TCP/IP → New Connection (or System Parameters if you want to set unit-level defaults such as cycle time and time-out).

Step 6 — Define the Connection Properties

For a TCP/IP connection the properties dialog contains the following critical fields:

Click Test Connection in the connection properties. A successful test returns the message "Connection successfully established" and the green status icon appears next to the connection in WinCC Explorer.

Step 7 — Create Tags

1. Expand the new connection under TCP/IP.
2. Right-click the connection → New Tag.
3. Assign a name (WinCC tag name), a data type (BOOL, INT, REAL, WORD, etc.), and a PLC address in the form DB<n>.DBX<x>.<y>, DB<n>.DBW<x>, DB<n>.DBD<x>, or M<x>.<y>, I<x>.<y>, Q<x>.<y>.
4. Set the length if the data type is a string or raw byte array.
5. Click Apply to compile the tag and check for syntax errors in the WinCC Output window.

Diagnostic Workflow and Error Codes

If the connection does not come up, work the following checklist before opening the WinCC logfile:

1. Physical layer: Verify the LINK LED on the CP 343-1 and the NIC link LED are both on. Swap the patch cable. Check the switch port is not administratively disabled.
2. IP layer: From a command prompt on the WinCC station, run ping <CP_IP_address>. A successful ping proves layer 3 reachability but not the S7 connection.
3. Access point: Re-open Set PG/PC Interface and confirm S7ONLINE points to the correct access for the chosen channel unit.
4. Slot number: Confirm the slot number entered in the WinCC connection properties matches the physical slot of the CPU in HW Config.
5. WinCC logfile: When all of the above check out, the next step is to read the S7 Protocol Suite logfile in the WinCC installation Diagnose folder (default C:\Program Files (x86)\Siemens\WinCC\Diagnose or C:\Program Files\Siemens\WinCC\Diagnose on 32-bit installations).

Verification Procedure

1. Activate WinCC Runtime. The status indicator at the bottom of the WinCC Explorer should show a green dot on the connection.
2. Open a graphics designer screen that displays a tag from the new connection and verify the value updates with a known process variable.
3. Trigger a forced value in STEP 7 on a flag in the PLC and confirm the value propagates to the WinCC tag within the configured update cycle (default 1 s for TCP/IP).
4. Use the WinCC Channel Diagnosis tool to inspect connection statistics (failed transmissions, retries, last error code).

Performance Notes and Practical Limits

For a typical CP 343-1 + Softnet-IE Lean installation on Windows 7 64-bit, observe the following practical limits during sizing:

• Update cycle: 250 ms is a stable lower bound for the TCP/IP channel with up to 500 tags per second. 1 s is the recommended default.
• Tag count: WinCC itself supports tens of thousands of tags; the practical limit is the cycle time × number of tags ÷ throughput of the Softnet-IE Lean driver (≈ 200 tags per polling slot).
• Concurrent connections: Up to 8 S7 connections on Softnet-IE Lean, up to 64 on Softnet-IE or Hardnet-IE S7.
• Network design: Place the WinCC PC and the S7-300 station in the same VLAN. Avoid crossing a router or WAN for the S7 link; ISO-on-TCP does not traverse NAT.

Frequently Asked Questions