TP177B PN/DP: Resolving 'No Establish Connection' Transfer Error

Problem: TP177B 6" PN/DP 'No Establish Connection' During Transfer

The SIMATIC TP177B 6" PN/DP (MLFB 6AV6642-0BA01-1AX1) is a STN 256-color panel with MPI/PROFIBUS DP (RS485/RS422), USB host, and Ethernet 10/100 interfaces. When engineers attempt project transfer from WinCC flexible to the panel using the USB PC Adapter (6ES7 972-0CB20-0XA0), the software reports "No establish connection" and the transfer aborts. This is not a configuration bug — it is a hardware/protocol compatibility constraint enforced by Siemens.

Affected Hardware and Part Numbers

Root Cause Analysis

The TP177B PN/DP exposes multiple physical interfaces, but the transfer channel is restricted to a subset of them by Siemens firmware policy. The error "No establish connection" appears when the configured channel in WinCC flexible cannot be reached by the panel's transfer dispatcher, or when the hardware handshake fails.

Three primary root causes are observed in field service:

1. Unsupported cable/interface pairing. The PC Adapter USB and PC/MPI Adapter are not approved for transferring the TP177B, TP177A, TP170, OP177, and TP270 families. WinCC flexible will still allow the operator to select these interfaces, which leads to a failed handshake.
2. PG/PC interface set to the wrong driver. Even on a supported cable (RS232 PPI), the PG/PC interface in the Control Panel must be bound to PPI or Ethernet TCP/IP, not to PC Adapter (MPI) or PC Adapter (PROFIBUS).
3. Transfer mode disabled on the panel. The TP177B must have Transfer enabled in the Control Panel / Loader and the Channel set to either Serial or Ethernet. Some panels ship with transfer locked out for security.

Resolution Path: Choose a Supported Transfer Channel

The TP177B PN/DP supports exactly two transfer channels:

• Channel 1: Ethernet (10/100) on the PN port — preferred for speed and modern PCs without a serial port.
• Channel 2: RS232 PPI via the panel's sub-D interface and the RS232 PPI Multi-Master cable — preferred when no Ethernet switch is available or when the panel IP is unknown.

Both methods require WinCC flexible 2007 SP2 or later (SP3 / SP4 / SP5 / 2008 also valid). Earlier WinCC flexible versions cannot fully support the TP177B device image.

Method 1: Ethernet Transfer (Recommended)

Prerequisites

• TP177B PN/DP panel (6AV6642-0BA01-1AX1).
• WinCC flexible 2007 SP2 or later installed on the engineering station.
• Standard RJ45 patch cable (the PN port supports Auto-MDIX, so a 1:1 cable works for direct PC connection).
• Panel IP address known (default: 192.168.0.1, subnet 255.255.255.0) or retrievable via the panel's loader.

Step-by-Step Procedure

1. Configure the panel IP address. On the TP177B loader, open Control Panel → Network. Set a static IP (e.g. 192.168.0.1), subnet mask 255.255.255.0, and disable DHCP. Press Apply and reboot the panel if prompted.
2. Configure the engineering PC IP. Set the PC Ethernet adapter to a static address in the same subnet, e.g. 192.168.0.10, mask 255.255.255.0. Do not assign a gateway unless routed transfer is required.
3. Verify connectivity. From the PC command line, run ping 192.168.0.1. A reply confirms Layer 3 reachability. If ping fails, swap the cable and re-check the port LEDs on the panel (green/yellow link lights).
4. Open the project in WinCC flexible. In the project tree, right-click the TP177B device and select Transfer → Ethernet. Enter the target IP 192.168.0.1 and click Transfer.
5. Trigger the panel to accept the transfer. If the panel is in normal operation, the transfer is rejected. On the panel, open the loader and start Transfer; the panel will wait for an incoming connection from the PG/PC.
6. Monitor the progress bar. A typical 2 MB TP177B project transfers in 30–60 seconds over Ethernet. The panel automatically restarts after a successful transfer.

Method 2: RS232 PPI Transfer (No Ethernet)

Prerequisites

• RS232 PPI Multi-Master Cable (6ES7 901-3CB30-0XA0) — note this is a serial cable, not USB.
• PG/PC with a 9-pin COM port (or USB-to-RS232 adapter if no native COM exists).
• WinCC flexible 2007 SP2 or later.

Step-by-Step Procedure

1. Connect the cable. Plug the 9-pin D-sub end of the PPI cable into the PC's COM port, and the panel-end connector into the TP177B RS422/485 sub-D port.
2. Set the PG/PC interface. In WinCC flexible, open Options → Set PG/PC Interface. Select PPI as the access point and bind it to COM1 (or whichever COM port the cable is attached to). Baud rate is auto-negotiated by the PPI cable (typically 19.2 kbps or 187.5 kbps depending on panel version).
3. Enable transfer on the panel. On the TP177B loader, navigate to Transfer, set Channel to Serial, and confirm Enable is checked. Return to the loader home screen.
4. Initiate the transfer. In WinCC flexible, choose Transfer → Serial (PPI). The transfer starts when the panel receives a valid PPI request. Progress is shown in the WinCC flexible dialog.
5. Wait for panel restart. Upon successful completion, the panel reboots into the new project.

PG/PC Interface Reference (WinCC flexible / STEP 7 Set PG/PC Interface)

Firmware and Software Compatibility

The TP177B PN/DP panel image is supported by the following engineering environments (device integration):

• WinCC flexible 2007 SP2 / SP3 / SP4 / SP5
• WinCC flexible 2008 SP1 / SP2 / SP3 / SP4 / SP5
• WinCC flexible 2008 SP5 is the last release supporting the TP177B family before migration to TIA Portal (TP700 Comfort series is the TIA Portal successor).

Panel firmware (HMI image) updates are delivered as *.fwf files via the ProSave service tool or through WinCC flexible. The current HMI image revision for 6AV6642-0BA01-1AX1 is available in the Siemens SiePortal product entry linked at the end of this document.

TP177B Loader Transfer Settings (Panel-Side)

To access transfer settings, touch the Transfer icon in the panel loader (top-level menu shown during startup or when the runtime project has a Close project button configured). The relevant parameters are:

Troubleshooting Matrix

Verification Steps After Successful Transfer

1. Confirm WinCC flexible reports Transfer completed successfully with no error code.
2. Verify the panel restarts automatically and displays the new runtime project.
3. Open the panel's project information dialog (typically by pressing a configured Info button) and check the version timestamp matches the just-transferred project.
4. Run a connectivity test from the panel's Control Panel → Network to confirm the IP, subnet, and MAC are intact.
5. Re-enable any production-mode settings (autostart, password, screen saver) that may have been disabled for the transfer.

Diagnostic: Quick Decision Tree

• Does the PC have an Ethernet port? → Use Ethernet (Method 1).
• Is the panel in a network without a DHCP server? → Use static IP and Ethernet.
• Is the panel installed in a cabinet with no Ethernet drop? → Bring a laptop with a crossed/straight RJ45 and connect direct to the PN port.
• No Ethernet available at all? → Use the RS232 PPI Multi-Master cable (6ES7 901-3CB30-0XA0).
• PC has USB only (no COM)? → Add a USB-to-RS232 adapter (FTDI-based recommended) and use PPI; do not use the USB PC Adapter for transfer.

Related Notes and Field Caveats

The TP177B PN/DP is the Ethernet-capable variant in the TP177B family. The TP177B DP (no PN suffix) lacks the Ethernet port and is restricted to PPI/MPI transfer. Engineers are often confused by the part-number scheme: 6AV6642-0BA01-1AX1 is the PN/DP version with Ethernet; 6AV6642-0DC01-1AX1 is the Blue Mode STN variant; confirm the exact MLFB on the rating plate before troubleshooting the transfer interface.

For larger projects exceeding 4 MB, Ethernet transfer is strongly preferred — PPI serial transfer of a 4 MB+ project can take 10+ minutes and is more susceptible to interruption. Always verify the panel's Close project or Exit runtime button is configured before initiating a PPI transfer, because the runtime cannot be replaced while it is running and the loader must be active to accept the download.

For official product documentation, refer to the Siemens SiePortal product entry for MLFB 6AV6642-0BA01-1AX1, which lists the operating instructions, HMI image files, and the WinCC flexible device integration package. The WinCC flexible / TP transfer FAQ (entry ID 23800567) on the Siemens Support site provides the canonical list of supported transfer channels per panel model and is the authoritative reference when validating a transfer method.

FAQ