Siemens LOGO! 8 IP Address Setup: Troubleshooting Connection Issues

When a Siemens LOGO! 8 (6ED1052-1xx08-0BA0 base module family, including the 6ED1052-1AD08-0BA0, 6ED1052-1MD08-0BA0, and the pure 6ED1052-2MD08-0BA0 variants without onboard display) loses network identity or ships from a previous installation with an unknown static IP address, the standard recovery path is not through the LOGO!Soft Comfort project — it is through the device's onboard display and cursor keys. This technical reference covers the complete field procedure to read, change, and verify IP configuration on a running LOGO! 8 without disturbing the wiring, to regain communication from LOGO!Soft Comfort V8.x, and to recover from the common "I cannot find the IP" failure mode. The procedure applies to LOGO! 8.1 (FS:01), LOGO! 8.2 (FS:02), and LOGO! 8.3 (FS:03 and FS:04) base modules equipped with the integrated Ethernet interface.

1. Problem Statement and Field Symptoms

The failure mode typically presents as one of the following combinations, all of which share the same root cause — the device is reachable over Ethernet but its currently configured IP address is not known to the engineering workstation.

• LOGO!Soft Comfort V8.x displays Connection failed, No response from device, or the transfer dialog times out at 30 seconds when Online > Connect is invoked, despite the link LEDs on both the PC NIC and the LOGO! 8 RJ45 jack indicating physical-layer connectivity.
• The default address 192.168.0.3 (the LOGO! 8 factory default IP for the first installed base module) does not answer an ICMP echo, although the same PC and cable successfully connect to a second, unconfigured LOGO! 8 plugged into the same switch port — confirming that the cable, NIC, and switch path are healthy.
• The LOGO! 8 onboard display is alive and continues to show a program-driven run-time text (for example, an internal timer or counter value being displayed as configured in the original FBD), confirming that the program is executing and the controller has not entered a fatal error or stop-on-fault state.
• Scrolling with the ▼ cursor key reveals only the status screens for digital inputs (I1..I24, depending on attached I/O expansion), digital outputs (Q1..Q20), analog inputs and outputs (AI1..AI8, AQ1..AQ8), and the Merker/flag bits (M1..M27). No network settings menu is visible while the program is running.
• The network administrator has no record of the assigned IP, the original programmer is no longer with the organization, and there is no backup of the LOGO!Soft project file (.lsc / .lma) on the engineering workstation.

These symptoms point to a configuration state that the LOGO! 8 explicitly enforces: network parameters are read-only while the controller is in RUN, and RUN is the only state in which the operator menu exposes the I/Q/M status screens the engineer is currently viewing.

2. Root Cause Analysis

The Siemens LOGO! 8 enforces a strict access model for network configuration that depends on two independent state variables: the program run state (RUN vs STOP) and the user authorization level (Operator vs Administrator). Network parameters — IP address, subnet mask, and default gateway — are mutable only when both conditions are satisfied simultaneously.

The default authorization for a new device is Operator; only the user who has successfully entered the administrator password can elevate the device. The factory administrator password for all LOGO! 8 firmware versions is the literal string LOGO (four uppercase characters). If a previous integrator or maintenance technician changed this password and did not record it, a network-edit recovery is not possible without a factory reset (see Section 12).

3. Prerequisites and Required Tools

Before opening the cabinet, confirm the following items are available. The procedure uses only the LOGO! 8 onboard HMI — no PC connection is required to recover the IP.

• Physical access to the LOGO! 8: The 6-line LCD and the 6-button cursor pad (ESC, OK, ▲, ▼, ◄, ►) must be reachable without removing the device from the DIN rail. On LOGO! 8.3 base modules with onboard display (6ED1052-1xx08-0BA0), the 6-line backlit LCD is integrated; on the LOGO! 8.3 pure variant (6ED1052-2xx08-0BA0) without onboard display, an external LOGO! TDE (6ED1055-4MH00-0BA0) must be connected to the expansion port on the right side of the base module.
• Administrator password: The string LOGO if the device has not been reconfigured. Any modified password must be obtained from the installation documentation or from the previous programmer.
• Target network parameters: A free IP address inside the operational subnet, the subnet mask (typically 255.255.255.0), and the default gateway (typically the router at x.x.x.1 or x.x.x.254). Confirm the address is not in the DHCP pool and does not conflict with any existing device by pinging the candidate address first.
• Process authorization: Permission to stop the LOGO! 8 for the 30–90 seconds the procedure takes. If the LOGO! is in a closed-loop control path, arrange for an alternate controller or accept that outputs will drop to their STOP-state fallbacks (digital outputs to 0, analog outputs to undefined — typically the last value held by the DAC).
• Ethernet patch cable (Cat 5e or better, straight-through): One end to the LOGO! 8 RJ45, the other to a PC with LOGO!Soft Comfort V8.0 or later. A crossover cable is not required; the LOGO! 8 and all modern PC NICs support Auto-MDI/MDIX. Maximum cable length is 100 m per IEEE 802.3u 100BASE-TX.
• LOGO!Soft Comfort V8.x: Installed on a Windows PC. Versions V8.0, V8.1, V8.2, V8.3, and V8.4 are compatible with LOGO! 8 base modules. Match the project firmware version (FS) to the device FS when transferring new programs; a project saved in V8.3 (FS:04) cannot be downloaded to a device with FS:02.

4. Understanding LOGO! 8 Operating Modes

From the perspective of the onboard menu, the LOGO! 8 has three distinct top-level states, each with a different default landing screen after the ESC key is pressed.

The diagnostic value of this table is that the very first menu item you see after pressing ESC tells you which authorization state you are in. If you see Program at the top, you are in Operator mode and the entire network-edit path is closed. If you see Stop at the top, the device is already in Administrator mode and you can proceed to Section 6. If you see Start at the top, the device is in Administrator mode but the program is currently stopped — you can edit the IP without re-entering the password.

5. Procedure: Accessing Administrator Mode via Display

The following steps elevate the device from Operator to Administrator. Perform them with the controller powered and the program executing.

1. Navigate to the standard status display. From the default message screen (the run-time text the previous programmer configured), press ▼ to scroll through any custom message screens, the digital input status, digital output status, analog I/O status, and flag status until you reach the standard built-in status display. The standard status display is the screen that shows I1: 0 I2: 0 ... Q1: 0 ... in the fixed LOGO! layout with no message text on the third line.
2. Press ESC to return to the main menu. A short press moves up one level; on the standard status display, one press of ESC lands on the main menu. The first item in the main menu is the current top-level state indicator.
3. Read the top menu item.
   • If the top item is Stop or Start — the device is already in Administrator mode. Skip to Section 6.
   • If the top item is Program — the device is in Operator mode. Continue to step 4.
4. Open the Setup submenu. Use the ▼ key to move to the second menu item, Setup, and press OK.
5. Select Switch to ADMIN. Inside the Setup submenu, navigate to Switch to ADMIN and press OK.
6. Enter the administrator password. The device prompts for a password. Use ▲/▼ to change the character at the cursor position, ►/◄ to move the cursor, and OK to confirm each character. The default password is LOGO (all uppercase, four characters). Press OK after the fourth character.
7. Verify acceptance. If the password is correct, the display returns to the main menu and the top item is now Stop (or Start if the program was already halted). If the password is incorrect, the display briefly shows Wrong password and returns to the status display without changing the authorization. Three consecutive failed attempts do not lock the device, but a long delay may be inserted between attempts as a soft rate limit.

6. Procedure: Transitioning to STOP State

With Administrator mode active and the program in RUN, the controller must be stopped to unlock IP editing.

1. From the main menu with the top item reading Stop, press OK.
2. Confirm the stop action if the device prompts Stop program? by selecting Yes and pressing OK.
3. Wait for the status display to change from a running program output to a static state. All digital outputs drop to their configured fallback (typically 0), analog outputs hold their last value or drop to 0 V / 0 mA depending on the configured STOP behavior, and timers reset. The display now shows a static status line indicating the program is halted — the run-time message text is replaced with --- STOP --- on FS:03+ firmware.
4. Press ESC once to return to the main menu. The top menu item is now Start (because the program is stopped) or, in some firmware versions, Program. In both cases, the device remains in Administrator mode across the RUN→STOP transition — the password is not re-prompted.

7. Reading the Currently Configured IP Address

With the device in STOP and Administrator mode, the network parameters become visible in the Setup submenu.

1. From the main menu, navigate to Setup and press OK.
2. Select Network (in firmware FS:01 and FS:02, the LOGO! 8.1 and 8.2 menu structure) or IP Address (in firmware FS:03 and FS:04, the LOGO! 8.3 menu structure). Press OK.
3. The display now shows three sub-screens, navigated with ▼:
   • IP Address: 192.168.000.003 — the current IPv4 address. Leading zeros are not stored; they are only a display convention for fixed-width alignment on the 6-line LCD.
   • Subnet Mask: 255.255.255.000 — the current subnet mask.
   • Gateway: 192.168.000.001 (or whatever value was last configured).
4. Record these values on paper or photograph the display. Even if the values appear to be inside the same subnet as the PC, the device may have been assigned an address that is no longer in the PC's ARP cache or that is being filtered by a managed switch with MAC-age-out settings shorter than the engineering workstation's traffic pattern. Recording the values is a prerequisite for editing and for verifying connectivity after the change.

8. Editing IP Address, Subnet Mask, and Gateway

Editing follows the same navigation pattern as reading, with OK switching from view to edit mode and the cursor keys selecting octets and digits.

1. With the IP Address line displayed, press OK. The first octet begins to flash.
2. Edit the first octet with ▲/▼ (digit value) and ► (next position). Press OK to confirm.
3. The cursor moves to the second octet; repeat. After the fourth octet is confirmed, the device validates the address against the subnet mask. The address must be a valid host address inside the configured subnet; the network address (host portion all-zero) and broadcast address (host portion all-one) are rejected by the firmware.
4. Press ▼ to move to Subnet Mask and press OK to edit. The mask is selected from a fixed list: 255.255.255.0 (Class C, /24), 255.255.0.0 (Class B, /16), 255.0.0.0 (Class A, /8), and the CIDR-mapped forms /25 through /30 for subnetting. Choose the mask that matches the operational network.
5. Press ▼ to move to Gateway and press OK to edit. The gateway is optional — set it to the router address inside the same subnet, or leave it as 0.0.0.0 if the LOGO! is on a leaf network and only communicates peer-to-peer with LOGO!Soft on the same subnet.
6. Press ESC repeatedly to back out to the main menu. The device prompts Save changes?. Select Yes and press OK. The new IP parameters are written to non-volatile flash.

9. Returning to RUN Mode and Verifying Communication

After the IP change is saved, return the device to RUN to restore normal operation.

1. From the main menu, select Start (top menu item) and press OK. Confirm Start program?.
2. The display returns to the run-time text or status screen. Outputs come out of STOP-state and re-execute the program logic on the next scan.
3. Power-cycle the LOGO! 8 to bind the new IP — pull the terminal block or the 24 V supply, wait 5 seconds for the network capacitors to discharge, and re-apply. Wait for the program to be in RUN before testing connectivity.
4. On the PC, open a Command Prompt and ping the new IP: ping 192.168.0.50 (replace with the actual assigned address). A successful reply with sub-10 ms latency on a directly-connected switch confirms layer-3 reachability.
5. If ping fails, verify the PC's own IP is in the same subnet. A PC with 192.168.1.10 / 255.255.255.0 cannot reach a LOGO! at 192.168.0.50 / 255.255.255.0 without a router. Add a secondary IP to the PC NIC via ncpa.cpl > Properties > IPv4 > Advanced > Add, or re-IP the PC into the same subnet for the test.

10. Connecting from LOGO!Soft Comfort

With the IP verified at the ICMP layer, the LOGO!Soft Comfort V8.x session is straightforward.

1. Launch LOGO!Soft Comfort V8.x. Confirm the version matches the device FS (functional state) — V8.0 for FS:01, V8.1 for FS:02, V8.2 for FS:03, V8.3 for FS:04.
2. Open the Tools > Options > Ethernet Interface dialog and verify the PC's network interface card is selected from the dropdown.
3. Open the Tools > Address Book (or Options > Address Book in V8.3+). Add a new entry:
   • Name: A descriptive label, e.g., Cabinet1_LOGO8
   • IP Address: The new IP just configured on the device
   • Subnet Mask: Same as configured on the device
   • Gateway: Same as configured on the device (or blank if 0.0.0.0)
4. Click Online > Connect (or the toolbar transfer icon). The status bar at the bottom of LOGO!Soft cycles through Connecting → Connected. The firmware version, project name, and operating mode of the device appear in the status pane.
5. Click Online > Upload from device to retrieve the program, or Online > Stop to take control of the program state for a controlled download. From the same menu, Online > PC > LOGO! transfers the currently open project to the device.

11. Ethernet Cabling and Link Verification

The original report mentioned swapping cables to confirm a working cable; the LOGO! 8 RJ45 jack has two link-state indicators built into the body. Both should be inspected before assuming a software fault.

LOGO! 8 supports 10/100 Mbit/s full-duplex with Auto-Negotiation and Auto-MDI/MDIX. A straight-through Cat 5e patch cable is sufficient for any connection — to a switch, to a router, or direct to a PC. Crossover cables are not required for any modern combination. Maximum cable length is 100 m per IEEE 802.3u 100BASE-TX. For runs longer than 80 m in electrically noisy cabinets, use shielded twisted pair (STP, Cat 6 or better) with the shield bonded to the cabinet ground at one end only to avoid ground loops.

12. Factory Reset: Last Resort Recovery

If the administrator password has been changed and is not documented, a factory reset is the only way to recover write access to network parameters. A factory reset also erases the stored FBD/LAD program and all run-time message text — it is destructive.

1. Power off the LOGO! 8 by removing the 24 V supply from the power terminals (L+, M on the left side of the base module).
2. Hold down the ESC and OK keys simultaneously on the device while powering the device back on. On LOGO! 8.3, use the right-most two keys on the cursor pad (ESC and OK).
3. The display shows Factory reset?. Press OK to confirm or ESC to abort.
4. The device reboots with factory defaults: IP 192.168.0.3, subnet mask 255.255.255.0, gateway 192.168.0.1, administrator password LOGO, no program, no run-time text, auto-start disabled.
5. Reprogram the device from a known-good backup of the FBD/LAD project, or rebuild the program from documentation. If the project was stored on a Siemens LOGO! memory card and the card was used to clone the device before the password change, the program can sometimes be reloaded by inserting the card and triggering a menu load (the device will prompt Load from card? on power-up).

13. Configuration Reference and Default Values

Reference values for the LOGO! 8 base module and its integrated Ethernet interface.

For cross-vendor integration, the LOGO! 8 supports a subset of the S7 communication primitives on TCP port 102. A standard S7-Put/Get client can read and write the LOGO! VM mapping (variable memory) and the process image of the inputs and outputs. This is the integration path used by most SCADA drivers and by libraries such as libnodave and Snap7. The LOGO! VM address space is byte-addressed, with the standard mapping: VB0..VB850 for variables, IB0..IB3 for the digital input image, QB0..QB2 for the digital output image, and MB0..MB3 for the Merker/flag bits. Refer to the Siemens LOGO! 8 system manual for the full register map and the function codes supported on TCP port 102.

14. Web Server and Modbus TCP (V8.2+)

Starting with firmware FS:02 (LOGO! 8.2), the device includes a built-in HTTP web server on TCP port 80. The web server provides a read-only view of the I/Q/M/AI/AQ status, the current IP configuration, and the firmware version. It does not allow program editing from the browser — LOGO!Soft Comfort remains the only authorized program editor.

To access the web server, point a browser at http://<logo-ip-address>/. The landing page authenticates with the same administrator password as the on-device menu. If the web server is not responding, verify the firmware version is FS:02 or higher and that no firewall on the engineering PC is blocking outbound port 80.

The Modbus TCP server on TCP port 502 is enabled by default starting in V8.0. The server exposes the LOGO! VM area as holding registers, with byte 0 of the VM area mapped to register 0. Function codes 03 (read holding registers), 06 (write single register), and 16 (write multiple registers) are supported. The server is read/write — write access is gated by the same administrator password, which the Modbus client must present in the standard Modbus TCP authentication slot (the LOGO! 8 uses a simplified scheme where the password is sent as the first two registers of the write request, ASCII-packed).

15. Troubleshooting Matrix

16. Frequently Asked Questions