How to Transfer WinCC Flexible Projects to Siemens HMI Panels

Overview

Transferring a WinCC flexible project to a Siemens HMI panel (for example, OP77B, OP177B, TP177B, or MP 277 10" Key) requires the engineering station (PG/PC) to be physically or logically connected to the target panel, the WinCC flexible project to be in a consistent state, and the panel itself to be placed in Transfer mode. Three physical transfer paths are commonly used in the field:

• Serial RS232 transfer using a null-modem (crossover) cable on panels that expose an RS232 port (OP77B, OP177B mono, TP177B mono).
• MPI / PROFIBUS DP transfer using a Siemens PC Adapter (USB or RS232) on a Profibus segment that includes the panel.
• Ethernet (PROFINET) transfer on Windows CE panels such as the MP 277, using TCP/IP over the panel's IE port.

The transfer path is selected inside the WinCC flexible project under Project → Transfer → Transfer Settings, where the channel and parameters (COM port, baud rate, MPI address, IP address, MAC) are stored. See the official Siemens WinCC flexible Ethernet Transfer manual (PDF) for the Ethernet-specific switch from "SOFTBUS" / "MPI/DP" to Ethernet or HMI IE.

Prerequisites

1. WinCC flexible engineering software matching the panel's runtime version (WinCC flexible 2005 SP1, 2007, 2008 SP1/SP2/SP3, or 2008 SP5). Mixing the panel image major version with an older ES is the most common cause of a refused download.
2. STEP 7 (optional but recommended) when the HMI project is integrated into the S7 project. With Integrate in STEP 7, the HMI and PLC share a single project, which guarantees consistent tag and connection data during transfer.
3. PC Adapter USB A2 (6GK1571-0BA00-0AA0) for MPI/DP, or a CP 5711 / CP 5512 PCMCIA/PCI card. A generic USB-to-RS485 adapter will not enumerate as a Siemens PG and is not supported.
4. Null-modem (crossover) RS232 cable, DB9 male-to-female, pins 2-3 crossed, 4-5 crossed, 6-20 crossed, for serial transfer to OP77B-class panels.
5. Profibus connector with PG socket (6ES7972-0BB12-0XA0) on the S7 PLC side, plus a Profibus cable terminated at both ends (terminating resistor ON at the two physical ends, OFF elsewhere).
6. 24 V DC supply to the panel. The OP77B MPI/DP port does not source 24 V, so the Profibus segment must be powered from the PLC; a panel sitting alone on a USB adapter will not power up its MPI/DP transceiver.
7. Panel in Transfer mode. For the OP77B the mode is toggled on the device (in the loader menu → Transfer); for Windows CE panels (MP 277) you also enable the transfer channel from the CE Control Panel → Transfer → set the channel to Remote (Remote On) before starting the download.

STEP 7 / WinCC Flexible Project Integration

The "s7 control" referenced in a typical Noobs guide is the S7 PLC program container inside the STEP 7 project. WinCC flexible offers two operating modes:

To integrate: open the S7 project in SIMATIC Manager, right-click the station → Insert SIMATIC HMI Station, then select the panel type. STEP 7 launches WinCC flexible and creates a new HMI project that is linked, not copied, into the S7 tree. From this point on, the two programs must be downloaded together if both are online.

Selecting the Transfer Interface

Open Project → Transfer → Transfer Settings in WinCC flexible. The dialog exposes the channel parameters shown below.

For an Ethernet-based download on a Windows CE panel, the channel must be changed from SOFTBUS to Ethernet (or HMI IE when using the on-board IE interface on a 200/300 series station). This is documented in the Siemens WinCC flexible Ethernet Transfer manual (PDF) — failure to switch the channel is the single most common cause of an "Ethernet: connection not established" fault at the start of transfer.

MPI/DP Transfer via PC Adapter (OP77B)

The OP77B exposes a single 9-pin sub-D MPI/DP port. To bring up a transfer session:

1. Open Start → SIMATIC → PC Adapter → Set PG/PC Interface on the engineering station.
2. Select the access point S7ONLINE and the interface parameterization PC Adapter (MPI) or PC Adapter (DP) — this must match the topology that the panel is wired into.
3. Set the PC Adapter local MPI/DP address to 0 (the PG default). The bus must not contain a second node with address 0.
4. Wire the bus: a Profibus connector with PG socket (6ES7972-0BB12-0XA0) on the S7 PLC, then a purple Profibus cable to a second Profibus connector on the OP77B. The PC Adapter plugs into the PG socket on the PLC connector.
5. Power the PLC (24 V ON). The OP77B will power its MPI/DP transceiver from the bus and the loader screen should appear.
6. On the OP77B, navigate to Loader → Transfer. The panel waits for a passive transfer.
7. Back in WinCC flexible, Project → Transfer → Transfer. Status "Establishing connection" should appear; a successful transfer ends with "Transfer completed" and a panel restart.

Serial Transfer via RS232 Null Modem (OP77B)

When MPI/DP wiring is impractical (small bench test, no PLC available) the OP77B supports a serial transfer over its RS232 port. The parameters are fixed by the panel firmware and must match exactly on the PC side.

Procedure:

1. Connect the PC COM port to the OP77B RS232 port (X2) with the null-modem cable.
2. On the panel, enter the loader and set Transfer → Serial. On Windows CE panels, the equivalent is Control Panel → Transfer → Remote → On; on the OP77B loader the toggle is Serial vs MPI/DP.
3. In WinCC flexible, open Transfer → Transfer Settings → Serial and select the COM port number. The baud rate field in WinCC flexible is informational; the actual baud is fixed at 19200 by the panel.
4. Click Transfer. The PC will issue a connect request; the panel acknowledges and the image streams. Typical 256 KB project: 30-60 s at 19200.

Ethernet Transfer (MP 277 and Windows CE Panels)

For the MP 277 10" Key and other Windows CE / Windows Embedded Standard panels, Ethernet is the preferred path because the IE port is independent of the PLC and does not require 24 V from the bus.

1. On the panel, open the Windows CE Control Panel → Network and Dial-up Connections → PN_X1 (PROFINET) and assign a fixed IP that is on the same subnet as the engineering station. Default gateway is left blank if direct connection is used.
2. Open Control Panel → Transfer on the panel. Set Channel 1 to Ethernet (or HMI IE for the 200/300 on-board IE), tick Remote, and click Apply. The panel will start listening on TCP port 1024 (WinCC flexible transfer) and, if enabled, 5001 (HMI Load).
3. On the PC, set the LAN adapter to a fixed IP in the same subnet (e.g. 192.168.0.10 / 255.255.255.0) and disable any other active network interfaces (Wi-Fi, VPN) to avoid routing conflicts.
4. In WinCC flexible, open Project → Transfer → Transfer Settings → Ethernet. Enter the HMI IP address. Tick Use router / gateway only if the PC and panel are on different subnets.
5. Click Transfer. The first attempt is always slower (3-5 s ARP / TCP handshake); subsequent attempts in the same session are sub-second.

Refer to the Siemens WinCC flexible Ethernet Transfer manual (PDF) for the full set of register/port numbers and for the behavior of GetOSUpdate when the panel image version does not match the project image version.

Configuring the PG/PC Interface

The PG/PC interface is a Windows-level setting shared by STEP 7, WinCC flexible, and the panel loader. The two access points used during HMI transfer are:

When switching between MPI and DP on the same PC Adapter, do not change the access point — change the Properties of the same PC Adapter device to switch the bus profile and baud rate. Mixing access points is the leading cause of "Online: cannot reach the partner" errors.

Putting the HMI in Transfer Mode

The procedure differs by panel family. The table below summarises the entry points.

Performing the Transfer in WinCC Flexible

1. Compile the project (Project → Compiler → Check Consistency) and resolve every entry in the Output window that is flagged with a red square. A project with unresolved cross-references will refuse to start the transfer.
2. Open Project → Transfer → Transfer or click the Transfer button on the toolbar.
3. WinCC flexible opens the active transfer channel, builds a TCP or serial session, negotiates the panel image version, and uploads the compiled .fwx runtime image to a temporary area in the panel's flash file system.
4. When the image is fully uploaded, the panel reboots into the new runtime. Do not power-cycle the panel during the 5-15 s window between the end of the upload and the loader appearing with the new project name — interrupting the flash commit leaves a partial image and forces a manual Reset to factory.
5. The status line in WinCC flexible shows "Transfer completed successfully" only after the panel has booted into the new project and reported a heartbeat.

PLC Simulator Limitations with Low-End Panels

WinCC flexible provides a runtime simulator (RT) that runs the HMI image on the engineering PC. The simulator is separate from the S7-PLCSIM CPU simulator. S7-PLCSIM emulates an S7-300/400 CPU but does not expose an HMI port, so the HMI cannot transfer to it. The combination S7-PLCSIM + WinCC flexible RT works only when both are started and connected to the same softbus instance on the PC.

For the smallest panels (OP3, OP7, OP77A, OP77B) the runtime simulator is not available; the only way to validate a project is to download to a real panel. The simulator can still be used to validate the WinCC flexible logic on any panel that does support it (TP170A, TP177B DP/PN, MP 277, etc.).

Troubleshooting Matrix

Verification and Commissioning

1. After a successful transfer, the panel boots into the project and the title bar / start screen of the HMI should appear within 30 s.
2. Open the connection diagnostics in WinCC flexible (Project → Transfer → Online → Diagnostic) and confirm that the configured PLC connection is in the Connected state. If multiple connections are defined (MPI/DP to one CPU, PROFINET to another), each must be green.
3. Force a single tag from the WinCC flexible tag table; the panel value should follow within one cycle of the configured update rate.
4. Cycle power on the panel; the project must auto-load and the connections must come up without manual intervention (no Transfer prompt).
5. Save the project, the panel image, and the connection configuration as a backup image on a USB stick or SD card using the panel's Service → Backup menu, so a future field failure can be recovered without re-engineering.

FAQ