Siemens LOGO! 8.3 Ethernet Connection Failure: V8.3 LSC Fix

Siemens LOGO! 8.3 Ethernet Connection Failure: V8.3 LSC Fix

The Siemens LOGO! 8.3 logic module (catalog number 6ED1052-1HB08-0BA1) ships with firmware that is incompatible with the older LOGO!Soft Comfort (LSC) V8.2.1 programming package. The symptom is a layer-2 Ethernet link (LED activity) without a usable application connection from LSC, and ping replies that succeed while the engineering software still reports "no connection." This article documents the root cause, identifies the affected hardware and firmware combinations, and provides the field-proven resolution.

1. Affected Hardware, Firmware, and Software

The reported fault is reproducible on the following product codes. Confirm the exact article number printed on the front of the LOGO! basic module (BM) before applying the fix.

Both the engineering software (LOGO!Soft Comfort) and the LOGO! firmware must be aligned. A V8.2.1 engineering package cannot program, monitor, or download to a V8.3 module, even when the TCP/IP link is otherwise healthy.

2. Root Cause Analysis

The handshake sequence between LSC and the LOGO! BM is a proprietary Siemens application protocol that rides on top of TCP port 102 (ISO-on-TCP / S7-comm-style framing) and TCP port 8443 for the LOGO! web server. When the LSC version predates the LOGO! firmware, the LOGO! rejects the older protocol variant during the connection setup phase.

The physical link LED on the bottom of the LOGO! module behaves as follows during a failed LSC V8.2.1 → LOGO! 8.3 attempt:

A successful ping 192.168.0.3 from the engineering laptop confirms that:

• The RJ45 cable is functional.
• The PC NIC is set to a compatible IP subnet.
• The LOGO! IP stack is running.

It does not confirm that LOGO!Soft Comfort can establish the application session. The application layer is where the version mismatch causes the connect attempt to time out with a "no connection" error.

3. LOGO!Soft Comfort / Firmware Compatibility Matrix

4. Required Network Configuration

Before re-attempting the connection with the correct software version, the IP plan must place the engineering PC and the LOGO! in the same subnet with no router between them. The classic direct-cable configuration is shown below.

4.1 Direct Connection, No Switch

4.2 Windows NIC Configuration (Windows 10 / 11)

1. Open Control Panel → Network and Sharing Center → Change adapter settings.
2. Right-click the wired Ethernet adapter and select Properties.
3. Select Internet Protocol Version 4 (TCP/IPv4) and click Properties.
4. Select Use the following IP address and enter:

IP address:      192.168.0.2
Subnet mask:     255.255.255.0
Default gateway: (leave blank)

5. Confirm with OK. Disable IPv6 on the same adapter to avoid duplicate-path issues during programming.
6. Temporarily disable the Windows Firewall and any third-party antivirus firewall while troubleshooting the LOGO! connection. Restore the firewall after commissioning.
7. Open an elevated cmd prompt and verify connectivity:

ping 192.168.0.3
arp -a

The expected reply is four echo replies with sub-millisecond RTT on a direct cable. The arp -a entry should show the MAC address of the LOGO! next to 192.168.0.3.

5. Step-by-Step Resolution Procedure

5.1 Acquire LOGO!Soft Comfort V8.3

1. Log in to the Siemens Industry Online Support portal. A free Siemens account is sufficient.
2. Search for LOGO!Soft Comfort V8.3. The download is delivered as a single executable or an ISO image.
3. Verify the package version on the splash screen: LOGO!Soft Comfort V8.3 (build identifier printed under Help → About).
4. Install the package on the engineering laptop. The installer handles all required runtime components and the LOGO! USB/Ethernet driver.

Refer to the official Siemens LOGO! Communication Modules page for the supported toolchain and the latest matching firmware notes.

5.2 Update the LOGO! BM Firmware (Optional)

If the LOGO! firmware on the bench is older than V1.83.x and the application program written in LSC V8.3 requires V1.83.x symbols, perform a firmware update before commissioning:

1. In LSC V8.3, open Tools → Firmware Update.
2. Select Ethernet as the transfer channel.
3. Browse to the firmware .bin provided by Siemens.
4. Confirm the target IP and click Update. The module reboots; do not remove power.

5.3 Establish the Programming Connection

1. Connect the laptop and LOGO! with a Cat5e or Cat6 patch cable. Either crossover or straight-through is acceptable on modern NICs and on the LOGO! 8.3 port (Auto-MDI/MDIX).
2. Power the LOGO! BM with 24 V DC (or 230 V AC on the matching variant). Observe the bottom Ethernet LEDs: a green link LED with intermittent amber activity is the expected idle state.
3. Launch LOGO!Soft Comfort V8.3.
4. Open the project (or start a new project). Switch to Network View using the toolbar button at the bottom of the work area.
5. Right-click Ethernet Connections in the project tree and select Add Connection. The dialog referenced in the official LOGO!Soft Comfort online help opens.
6. Enter the LOGO! IP address 192.168.0.3 and a connection name of your choice.
7. Click Online → Connect to LOGO! (or press F3). The status bar should transition to Online and report the LOGO! firmware version.
8. Click PC → LOGO! (download) or LOGO! → PC (upload) as required.

An additional reference for the Ethernet connection dialog is the third-party integration document Siemens LOGO! Ethernet PLC Connection Guide which walks through Tools → Ethernet Connections from the HMI side; the LSC workflow uses the same dialog from the engineering side.

6. Verification Checklist

Run the following checks after the fix is applied. Each step must succeed before the connection is considered healthy.

1. Physical: Green link LED solid on the LOGO!; amber activity LED flashes during transfer.
2. Layer 3: ping 192.168.0.3 -t from the engineering laptop returns 100% success with RTT < 1 ms on a direct cable.
3. Layer 2: arp -a lists the LOGO! MAC address bound to 192.168.0.3.
4. Application: LSC V8.3 Online → Connect to LOGO! transitions to Online within 3 seconds and reports the firmware version in the status bar.
5. Transfer: A 4 KB test program downloads and uploads in < 5 seconds.
6. Watch window: Live I/O updates appear in the diagram view at the configured refresh rate (default 250 ms).
7. Web server: http://192.168.0.3 returns the LOGO! 8.3 web interface; the firmware version is reported as V1.83.x.

7. Extended Diagnostics

7.1 Confirm the Installed LSC Version

In LOGO!Soft Comfort, open Help → About LOGO!Soft Comfort. The build string must contain "V8.3" or higher. If the splash screen shows V8.2.x, the wrong package is loaded. Reinstall the matching version.

7.2 Confirm the LOGO! BM Firmware Version

Use the integrated display on the LOGO! BM:

1. From the status screen, press ESC to enter the menu.
2. Navigate to LOGO! → Diagnostics → Versions.
3. Record the FS (firmware state) and the Version field, for example V1.83.01 / FS:04.

On a headless LOGO! variant, browse to the LOGO! web server http://192.168.0.3 from any browser on the same subnet and read the firmware string from the home page.

7.3 Network Path Tests

If the direct cable test succeeds but the engineering session still fails, rule out intermediate infrastructure:

tracert 192.168.0.3
pathping 192.168.0.3 -n -q 10
netsh interface ip show address "Ethernet"

The output of pathping must show 0% loss at every hop. A single managed switch in the path adds latency but should not block the protocol. Disable Energy Efficient Ethernet (EEE, IEEE 802.3az) on the switch port if the link LED occasionally drops; some legacy PHYs are sensitive to EEE power-state transitions.

7.4 Firewall and Security Software

Windows Defender Firewall and most enterprise endpoint protection suites block inbound ISO-on-TCP traffic on port 102 by default. Add an inbound rule permitting the LSC executable LogoSoftComfort.exe to listen on TCP 102 and 8443, or temporarily disable the firewall for the duration of the session.

8. Troubleshooting Matrix

9. Catalog Reference and Spare-Parts Notes

For MRO and field replacement, the following Siemens article numbers are commonly involved. Confirm the exact MLFB on the unit before ordering.

10. Preventive Recommendations

1. Pin the LSC version to the firmware family. Tag every engineering laptop with the LOGO!Soft Comfort version matching the production fleet.
2. Document the firmware state on the as-built drawings. A simple FS:0x field prevents the next engineer from chasing the same symptom.
3. Use the LOGO! CSM (6GK7177) for cabinet Ethernet. The unmanaged switch removes a class of Auto-MDI/MDIX and EEE issues on long cable runs.
4. Reserve a static IP plan. Avoid DHCP for the LOGO!; lease renewals can interrupt long downloads.
5. Periodically check the Siemens support portal for firmware revisions and any LSC patch that addresses the engineering protocol negotiation.

11. FAQ