Siemens OP27 HMI Project Transfer: Download Mode and Cable Setup

1. Overview

The SIMATIC OP27 is a 5.7-inch STN-LCD monochrome graphics operator panel belonging to the legacy OP2x / OP3x family that Siemens derived from the earlier Coros line. The device integrates a 320 x 240 pixel display, 24 illuminated function keys, a system-key block, and a numeric/alphanumeric keypad, with a 32-bit RISC controller and integrated Flash memory for the project. Two physical interfaces are present on the rear of the unit: an RS-232 point-to-point port (IF1) used for serial engineering transfer from a PG/PC, and an MPI / PROFIBUS-DP port (IF2) capable of 1.5 Mbit/s for simultaneous connection to a SIMATIC S7 controller on the same bus.

Project transfer (also referred to as "Download" or "Commissioning transfer") moves the compiled *.pdb / *.fwd container built in the configuration tool into the OP27's non-volatile Flash. Transfer can be performed over RS-232, MPI, or PROFIBUS-DP depending on the available cabling and the active bus topology at the time of commissioning. Because the OP27 predates USB commissioning ports, the engineer must select the correct interface and enter Download Mode on the panel before the configuration tool is allowed to push the project.

Reference documentation for the panel hardware, bus interface pin assignments, and the original Coros-to-SIMATIC migration guidance is published by Siemens as support entry 1142800 - OP27, OP37 Operator Panels. The device manual itself is structured with Section III (Installation and Commissioning) containing Chapter 14 on transfer settings; the engineer should keep that manual on hand during commissioning.

2. Prerequisites

Before attempting a project transfer, confirm that the following hardware, software, and project prerequisites are satisfied:

3. Transfer Communication Options

The OP27 supports three distinct physical paths for project transfer. Each option has different maximum baud rates, address ranges, and prerequisites.

The configuration tool exposes these channels through the Transfer Settings dialog; the operator panel must independently be told which channel to listen on, which is part of the Download Mode menu described in Section 5.

4. Cable Wiring and Pinout

The serial cable 6ES7 901-1BF00-0XA0 is a pre-wired null-modem that crosses TxD/RxD and bridges RTS/CTS to DCD on the panel side. Pin reference for the OP27 IF1 (RS-232, 9-pin Sub-D male) is given below:

For the MPI / PROFIBUS-DP IF2 (9-pin Sub-D female), the standard PROFIBUS pin assignment applies (pin 3 RxD/TxD-P, pin 8 RxD/TxD-N, pin 6 +5 V bus termination, pin 5 GND). Use only PROFIBUS-certified connectors and keep the segment drop length under 1 m at 1.5 Mbit/s to avoid reflections.

5. Entering Download Mode on the OP27

The OP27 hides its transfer menu behind a key sequence that is only recognised at cold start. This is to prevent accidental project overwrite during a runtime cycle. The procedure is:

1. Power the OP27 OFF via the 24 V supply. Wait at least 5 s for the internal bulk capacitors to discharge.
2. Press and hold the ESC key and the Arrow Up key simultaneously. Both keys are physically located in the system-key cluster on the right-hand side of the front foil.
3. While holding both keys, apply 24 V DC to the rear terminal. The panel performs its POST and skips the project boot loader.
4. Within approximately 3 s after the screen lights, the message Download Mode appears. If a transfer password has been configured, the panel prompts for it at this stage.
5. Release ESC and Arrow Up. The panel now shows the Transfer menu with the four available channels listed.
6. Select the active channel using the function keys F1-F4:

Once a channel is selected, the panel idles on a screen reading Connecting to host... with the selected interface, baud rate, and station address printed in the upper-right corner. The configuration tool may now initiate the transfer.

6. Transfer Settings in ProTool / WinCC flexible

On the engineering side, the Transfer Settings dialog controls what is sent and on which channel. In ProTool V6.0 the path is File > Transfer > Transfer Settings. In WinCC flexible 2004+ the path is Project > Transfer > Transfer Settings.

The dialog exposes the following fields, all of which must match the OP27 Transfer menu selection from Section 5:

7. Step-by-Step Transfer Procedure (Serial Example)

1. Build the project in ProTool / WinCC flexible for the OP27 device target. Compile the project (Project > Compile > All) and confirm that the compiler reports zero errors.
2. Open File > Transfer > Transfer Settings and select the Serial channel with baud rate matching the panel (default 19 200 bit/s).
3. Connect the 6ES7 901-1BF00-0XA0 cable between the PC COM port and OP27 IF1.
4. Power the OP27 OFF, hold ESC + Arrow Up, apply 24 V DC, and release when Download Mode appears.
5. Press F1 for serial transfer; confirm the baud rate on the panel screen matches the PC setting. The panel now idles on Connecting to host....
6. On the PC, return to ProTool / WinCC flexible and choose File > Transfer > To OP (ProTool) or Project > Transfer > Transfer (WinCC flexible).
7. A progress bar shows the file transfer; typical 1 MB compiled project takes 30-90 s at 38 400 bit/s.
8. When the panel reports Transfer OK - Restart, remove the cable and cycle power once to confirm the new project boots cleanly.

8. Step-by-Step Transfer Procedure (MPI / PROFIBUS)

1. Set the OP27 MPI address using the arrow keys inside the Download Mode menu (default address 1, valid range 1-31). Save with Enter.
2. Connect the OP27 IF2 to the MPI/PROFIBUS segment using a PROFIBUS PG connector with the termination switch set correctly.
3. Confirm the PC has a CP 5611, CP 5613, or USB-MPI adapter and that the matching driver is loaded (MPI driver up to version 5.x; later STEP 7 versions may not include legacy support).
4. In ProTool, open Transfer Settings, choose MPI, set the OP27 station address, and set the PC's own MPI address (commonly 0).
5. Trigger Transfer > To OP. The first packet the panel receives is a connection request on its configured address; if the address does not match, the panel returns E: 0x07F3 and the transfer aborts.
6. On completion, leave the OP27 on the bus and exit Download Mode with F4 to start the new project.

9. Troubleshooting Matrix

10. Verification and Commissioning Checks

After a successful transfer the engineer must verify that the project boots, that the controller connection establishes, and that the configured tags resolve correctly. The recommended checks are:

• Cycle 24 V DC. Confirm the OP27 runs through POST and lands on the configured start picture within 15 s.
• On the runtime screen, press System > Information and confirm the project version and the connected PLC type and address.
• Trigger a tag write from a function-key button on the OP27 and verify the value reaches the S7 controller using STEP 7 Monitor/Modify.
• Re-enter Download Mode (ESC + Arrow Up) and confirm the panel reports the same transfer parameters as the project, which proves the Flash was actually overwritten.
• Save a backup of the compiled project folder and store it with the cabinet documentation; the OP27 has no built-in backup export.

11. Migration Notes to WinCC flexible / TIA Portal

ProTool V6.0 was the last configuration tool with full OP27 support. When projects are migrated to WinCC flexible 2004 SP1 or later, the migration wizard converts pictures, tags, and alarms but the following limits apply:

• WinCC flexible 2008 SP3 is the final release that still recognises the OP27 device target. Later WinCC flexible versions and TIA Portal drop support.
• Custom Coros scripts must be re-authored as WinCC flexible scripts; the migration log flags them as !UNCONVERTED.
• Passwords are not migrated. Re-enter the transfer password in the new project before transfer.
• Recipes and logs convert but require manual re-mapping of storage paths if a CF card (for OP37) was used; the OP27 has no removable media.

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