Resolving LOGO! 230RCE Ethernet Download Connection Failures

Problem Summary

An engineer cannot establish an online connection from LOGO!Soft Comfort v8.1.0 (build 2016-07-14 16-34) to a Siemens LOGO! 230RCE base module, order number 6ED1052-1FB00-0BA8, feature set FS-04. The device appears in the LOGO!Soft Comfort network discovery view and the program icon animates, but the Test action returns the dialog "Unable to access the remote device" and program transfer aborts. ICMP echo (ping) succeeds in both directions; the LOGO! Web Server login HTML is fetched on TCP 80 (the Web Server application is disabled but the page is still served); and the issue reproduces on two physically different PCs, with both direct Ethernet crossover wiring and via a 192.168.0.1 router. Windows Firewall was disabled on both test PCs without effect.

This article documents the layered diagnosis performed on the bench, the constraints imposed by feature set FS-04, and the four-part corrective procedure that restores online operation. The four causes that must be ruled in or out, in order, are:

1. Starter Kit or limited-edition LOGO!Soft Comfort install without the network transfer feature.
2. Software build v8.1.0 transfer-layer mismatch with the FS-04 firmware.
3. TCP port 8080 filtered or intercepted between the PC and the LOGO! base module.
4. LOGO! access control list rejecting the programming session, or a mis-configured Web Server flag.

Affected Hardware and Software Inventory

Capture the following data on paper or in the maintenance log before changing any setting. The combination of MLFB (order number), feature set, and software build is the key to ruling in or out the four candidate root causes.

Confirm the FS-XX feature set by reading the 2D data matrix code on the right side of the LOGO! 8 base module. The laser-etched text directly below the matrix prints FS-04. This is a critical step: selecting the wrong feature set in LOGO!Soft Comfort (FS-03, FS-05, or any non-matching FS code) causes the project upload to refuse the connection even when network parameters are perfectly aligned. The selection is made under Tools > Options > Device Selection and the active FS code is echoed in the status bar at the bottom right of the LOGO!Soft Comfort main window.

Network Behavior and Protocol Architecture

Three network-level observations narrow the fault significantly. Each is reproducible on the bench and rules out a category of causes.

1. ICMP works in both directions. The PC pings 192.168.0.15, the LOGO! pings 192.168.0.118, and both replies return in under 1 ms on a wired link. Layer 3 reachability and ARP are healthy.
2. LOGO!Soft Comfort discovery finds the device. The refresh button (two blue circular arrows) on the Tools > Transfer > Configure Network Connection dialog populates the IP and the LOGO! icon animates. Discovery uses the LOGO! broadcast protocol on UDP port 1968 and the path is open.
3. The Test action fails with "Unable to access the remote device". The Test button issues a structured connect request over TCP 8080 to read the LOGO! firmware banner and program slot. The dialog wording is generic and is shared with timeout, refused, and license-rejected failure modes.
4. HTTP traffic on TCP 80 reaches the LOGO!. Wireshark captures the LOGO! Web Server login page (HTML form posting to /login.htm). The browser is told that the Web Server is disabled, which means the LOGO! base module responds on TCP 80 but refuses the subsequent action because the Web Server application is switched off.

Symptom 4 is the most diagnostic: the LOGO! base module is reachable at the IP and TCP level, and the embedded Web Server application answers on port 80, but the programming transfer over TCP 8080 is refused. This is a strong indicator that the LOGO! is intentionally rejecting the connection, not that the network is dropping packets. The L1/L2/L3 path is verified; the failure is at the application layer.

Root Cause Analysis

From the bench data the failure is not a classic L1/L2 cabling issue, not a routing issue, and not a Windows firewall issue. The LOGO! base module acknowledges TCP 80 but refuses TCP 8080. There are four plausible causes; the field test sequence evaluates each before changing configuration.

Cause 1: Limited or Demo Edition of LOGO!Soft Comfort

LOGO!Soft Comfort ships in three forms: the unrestricted retail/installable build, the Starter Kit build (unrestricted but licence-key bound), and the Demo build distributed with the public download. The Demo build disables the PC to LOGO! download function but still allows project editing, simulation, and network discovery, so the operator sees the device appear in the network view and assumes the program transfer feature is available. The Test connection is the first time the licensing check is enforced on a network path, and the dialog wording "Unable to access the remote device" is the same generic wording the software uses for every TCP 8080 timeout, which is why a Demo install is easy to miss.

To verify the edition:

1. Open LOGO!Soft Comfort.
2. Select Help > About.
3. Read the line under "Edition". A retail install reports "LOGO!Soft Comfort V8.1.0" with no suffix. A Demo install reports "LOGO!Soft Comfort V8.1.0 Demo". A Starter Kit install reports "LOGO!Soft Comfort V8.1.0 Starter" with a serial number block.

If the edition reports Demo, install a licensed copy or activate a Starter Kit product key before continuing. Starter Kits sold through Siemens distribution channels ship with a full, unrestricted version of LOGO!Soft Comfort and a license key printed on the DVD sleeve. If no license is present, request a license transfer from the Starter Kit DVD sleeve or purchase a separate license from Siemens LOGO! distribution. The Test path will continue to fail with the same generic wording until the licensing check is satisfied.

Cause 2: LOGO!Soft Comfort v8.1.0 and FS-04 Transfer-Layer Mismatch

LOGO!Soft Comfort v8.1.0 (released July 2016) was published before the FS-04 feature set reached general availability. The release notes for v8.1.0 list compatibility with the FS feature sets that were shipping at the time. While v8.1.0 will open FS-04 projects and edit them on the workbench, the network transfer layer of v8.1.0 was validated against the pre-FS-04 protocol. The handshake that v8.1.0 issues includes a protocol version byte that FS-04 firmware answers with an incompatible status, and the client software falls back to the generic "Unable to access the remote device" error rather than reporting the protocol version mismatch explicitly. This explains why the device is discovered (the discovery beacon is unchanged across FS versions) and why the Test call fails after the icon animation.

Solution: upgrade LOGO!Soft Comfort to a release that explicitly lists FS-04 in the release notes. The first version of LOGO!Soft Comfort that added full FS-04 transfer support is V8.2.0, released as part of the LOGO! 8.2 update. Any maintenance release of V8.2 or V8.3 will also work. The installer is a free download from Siemens Industry Online Support; the existing project files are forward-compatible.

Cause 3: TCP Port 8080 Filtered or Intercepted

LOGO! 8 base modules listen for programming transfer on TCP port 8080. Some managed switches apply ACLs to non-standard ports; some corporate endpoint protection products open a man-in-the-middle socket on port 8080 for HTTP-alternative proxies; some VPN clients redirect port 8080 to a local proxy. With the Windows Firewall disabled, the host stack is open, but the issue is at the network egress or at the LOGO! base module. Verify with the following PowerShell command from the PC:

Test-NetConnection -ComputerName 192.168.0.15 -Port 8080

Expected output if the port is open: TcpTestSucceeded : True. If False, the LOGO! is not accepting connections on 8080 and the network is the suspect. Repeat the test with the PC directly connected to the LOGO! with a crossover cable and with no switch in the path. If the direct test passes and the switch test fails, the switch is filtering; if both fail, the LOGO! itself is rejecting the connection and the cause is one of the others listed here.

Cause 4: Web Server Flag and Access Control List

On LOGO! 8 the Web Server and the programming server are independent services. Disabling the Web Server in the LOGO! display menu (Options > Web Server Access > Off) does not stop the programming server, but the LOGO! also exposes an access control list of up to four IP addresses that are allowed to read/write programs. If the PC's IP (192.168.0.118) is not in the list, the connection is accepted and then dropped, again producing the generic "Unable to access remote device" wording. The access list is configured under Options > Access Control on the LOGO! display.

To check, navigate to Options > Access Control on the LOGO! and add 192.168.0.118 (or 0.0.0.0 to allow any host on the subnet) to the allowed list. Save the change and power-cycle the LOGO! to commit. The programming server will then accept connections from any host on the /24 subnet.

Pre-Flight Diagnostic Checklist

Work through the following checklist in order before changing any setting. The total time is about ten minutes and identifies the root cause in the majority of bench cases without further intervention.

1. Confirm the FS code on the device label. 2D barcode on the side of the LOGO! 8 base module, text directly below the matrix. Set the same FS code under Tools > Options > Device Selection in LOGO!Soft Comfort. The status bar at the bottom right echoes the active selection.
2. Read the Help > About edition line. Retail: no suffix. Demo: "Demo". Starter: "Starter". Replace a Demo install before continuing.
3. Click the animated "i" icon at the bottom right of the main window. The error string in the popup is the most specific diagnostic available from LOGO!Soft Comfort itself.
4. Run Test-NetConnection -ComputerName 192.168.0.15 -Port 8080 from PowerShell. Expect TcpTestSucceeded : True. If false, the network is dropping TCP 8080 traffic.
5. Open the LOGO! Web Server in a browser at http://192.168.0.15/. If the login page loads, L3 reachability and HTTP service are good. If the login page does not load, the IP is wrong or the network is down.
6. Capture a Wireshark trace of the Test action. Filter on tcp.port == 8080 and inspect the SYN, SYN-ACK, ACK, and first payload exchange. The exchange must reach a LOGO! banner for the connection to be considered valid.
7. Inspect the LOGO! access control list under Options > Access Control on the LOGO! display. Add 192.168.0.118 if missing.

Solution Path A: Verify Software Edition and License

Step 1 of the corrective sequence. A Demo or unlicensed install is the most common reason for the Test path to fail with a healthy network.

1. Open LOGO!Soft Comfort and select Help > About.
2. Read the edition line. If the suffix is Demo, close the application.
3. Insert the Starter Kit DVD or download the retail installer from Siemens Industry Online Support.
4. Install over the existing build. The installer preserves user projects in %USERPROFILE%\Documents\LOGO! Soft Comfort\Projects.
5. Enter the license key from the DVD sleeve (Starter Kit) or the license certificate (retail) under Help > License > Activate.
6. Restart LOGO!Soft Comfort and confirm the edition line no longer reports Demo.

Solution Path B: Upgrade LOGO!Soft Comfort for FS-04 Support

Step 2 of the corrective sequence. The transfer layer of v8.1.0 predates the FS-04 feature set. Upgrade to V8.2 or later.

1. Open a browser and navigate to Siemens Industry Online Support.
2. Search for LOGO!Soft Comfort V8.2 or later. Download the latest maintenance build of V8.3.
3. Run the installer. The installer prompts for the existing V8.1.0 install and upgrades in place; user projects are preserved.
4. Launch the new build and open the existing project. The conversion to the new FS code is automatic; the device selection in Tools > Options > Device Selection should be set to FS-04 to match the laser-etched code on the device label.
5. Click Tools > Transfer > Configure Network Connection, refresh, and click Test. Expect a success dialog within two seconds.

If the Test dialog now reports success, proceed to Verification Procedure below. If the dialog still reports "Unable to access the remote device", the cause is one of the remaining items and continue to Solution Path C.

Solution Path C: Resolve the TCP 8080 Network Path

Step 3. A network-layer block on port 8080 produces identical symptoms to a license or version problem. Diagnose with the Test-NetConnection PowerShell command and a direct crossover test.

1. Open PowerShell as Administrator.
2. Run Test-NetConnection -ComputerName 192.168.0.15 -Port 8080. Note the value of TcpTestSucceeded.
3. If False, disconnect the PC from the network switch and connect directly to the LOGO! with a crossover cable. Repeat the test.
4. If the direct test passes, the switch is filtering. Replace the switch or add an exception for TCP 8080 in the switch ACL.
5. If both tests fail, the LOGO! base module may have a corrupted firmware or the access control list may be blocking all hosts. Continue to Solution Path D.
6. Check endpoint protection on the PC. Some products (Symantec, McAfee, Sophos) install a Winsock LSP that intercepts port 8080. Temporarily disable the endpoint protection to confirm. Re-enable after the test.

Solution Path D: Configure Web Server and Access Control List

Step 4. The programming server and the Web Server are independent on LOGO! 8, but the access control list applies to both. A mis-configured list will reject the programming session even when the Web Server is disabled.

1. On the LOGO! 8 base module, press ESC until the top-level menu is shown.
2. Navigate to Options > Access Control.
3. Read the four entries. If 192.168.0.118 is not present, add it. Use the cursor keys to edit each octet, OK to confirm each octet, and OK again to commit the entry.
4. If the list is full, replace one of the four entries with 192.168.0.118. For a bench setup, replacing all four with 0.0.0.0 (allow any) is acceptable.
5. Power-cycle the LOGO! 8 base module. The change is committed on power-up.
6. Re-run the Test action in LOGO!Soft Comfort.

Wireshark Diagnostic Procedure

When all four solution paths above still leave the issue unresolved, capture a Wireshark trace of the failing Test action. The trace is the definitive diagnostic and will identify whether the LOGO! is sending a TCP RST, a TCP FIN, or simply not responding.

1. Download and install Wireshark from the official Wireshark Foundation site.
2. Start a capture on the Ethernet interface connected to the LOGO! 8 base module.
3. Apply a capture filter: tcp.port == 8080 || udp.port == 1968. This filters to LOGO! discovery (UDP 1968) and programming transfer (TCP 8080) traffic only.
4. In LOGO!Soft Comfort, click the refresh button (two blue circular arrows) on the Tools > Transfer > Configure Network Connection dialog, then click Test.
5. Stop the capture after the dialog raises the error. Apply a display filter: ip.addr == 192.168.0.15 && tcp.port == 8080.

Interpret the trace against the following decision table:

Verification Procedure

Confirm the corrective action was successful with the following five checks, in order. Each check is independent and can be performed on the bench.

1. Test connection from LOGO!Soft Comfort. Open Tools > Transfer > Configure Network Connection, click Test. Expect a success dialog within two seconds and the message Connection successful or the equivalent localized text.
2. Download a small program to verify end-to-end transfer. Create a one-line program (for example output Q1 driven by input I1), then Tools > Transfer > PC → LOGO!. The transfer should complete in under five seconds for a program of this size.
3. Read the program back from the LOGO!. Tools > Transfer > LOGO! → PC. The downloaded program should match the program sent in step 2. A mismatch indicates a version or FS code mismatch that the Test dialog did not catch.
4. Run a STOP / RUN cycle. On the LOGO! display, switch to RUN. The I1 to Q1 path should toggle when input I1 is forced. Switch to STOP on the LOGO! display and confirm Q1 falls.
5. Restore the original program and save the project. File > Save As, file name bench_test.lsc, and commit to the project repository.

Field-Proven Caveats and Troubleshooting Matrix

Three operational caveats are worth recording in the maintenance log alongside the resolution.

• Discovery is not a transfer. UDP 1968 beacon and TCP 8080 transfer use different code paths in the LOGO! base module. A device that appears in the discovery view is not necessarily able to accept a program transfer. Always run the Test action before assuming the link is healthy.
• Web Server and programming transfer are independent. Disabling the Web Server in the LOGO! display does not stop the programming server. The two services share an access control list, however, and a mis-configured list blocks both.
• FS-04 is a feature set, not a firmware version. The feature set is printed on the device label and is independent of the firmware build number. Two LOGO! 8 base modules with the same firmware can have different feature sets if the device labels differ. Match the FS code in LOGO!Soft Comfort to the device label, not to the firmware version.

Frequently Asked Questions