Siemens OP27 Transfer Mode Failure: ProTool Download Guide

Siemens OP27 Transfer Mode Failure: ProTool Download Guide

The Siemens SIMATIC OP27 is a text-based operator panel from the OP series, configured and downloaded with ProTool/Pro V6.x. When the panel refuses to enter transfer mode on power-up, the failure usually traces to one of three areas: a missed or incorrect key sequence, a missing or corrupt firmware image, or an incorrectly wired IF2 serial link to the PC. This guide consolidates field-proven diagnostics, key sequences, the IF2 cable pinout, and recovery procedures for the OP27.

1. Problem Statement

Symptom: 24 V applied to a new or freshly reset OP27, ESC + ArrowUP held throughout the rising edge, and the panel does not respond with the expected "Transfer..." or download prompt. ProTool cannot establish a connection to the panel over the IF2 serial port. The operator panel either boots directly into a blank project screen or displays "No project" without ever offering the transfer handshake.

Affected units and configurations:

• OP27 6AV3 627-1JK00-0AX0 and 6AV3 627-1JK00-1AX0 (mono, text-display variants)
• OP27 / OP37 families configured with ProTool V6.0 or ProTool/Pro V6.0 SP2+
• Brand-new units shipped without preloaded firmware or with empty flash
• Used units that were last configured with a third-party tool or abandoned mid-flash

2. Root Cause Analysis

Three failure modes dominate OP27 transfer-mode issues in field service work:

1. Key sequence timing error. The transfer key combination is timing-sensitive. Buttons must be held before 24 V is applied and released only after the transfer prompt appears. A defective or worn ArrowUP membrane produces the same symptom: the bootloader never detects the key, so the runtime boots instead of the transfer dialog.
2. Missing firmware on flash. A brand-new OP27 may have its flash file system empty. The bootloader cannot mount the runtime that hosts the transfer dialog. A memory card with the firmware image must first be used to load the runtime, or ProTool V6.0 SP3+ must be used to push firmware over IF2.
3. Cable, COM port, or handshake mismatch. A generic 9-pin extension, a USB-to-serial converter without proper RTS/CTS timing, or wrong ProTool COM settings prevent the panel from acknowledging the PC. The OP27 will sit in the transfer prompt indefinitely and ProTool will report "Timeout" or "No response from panel".

3. Prerequisites

• ProTool V6.0 SP2 minimum, SP3 or later strongly recommended, installed on a Windows 2000/XP PC.
• Siemens PC <-> OP serial cable, order number 6XV1 440-2KH10 (9-pin female D-sub on the PC end, 15-pin male D-sub on the OP27 IF2 end).
• A free native COM port. USB-RS232 adapters from Belkin and generic FTDI-based units have known handshake timing issues with ProTool; prefer native COM1 (IRQ4) or COM2 (IRQ3).
• 24 V DC supply capable of 0.5 A minimum. The OP27 draws approximately 0.35 A typical, with cold-start inrush up to 0.5 A.
• Compiled OP27 runtime file (typically OP27.bin or *.img) and project *.pdz generated by ProTool.
• For memory-card recovery: a 4 MB minimum, 16 MB maximum Type I/II SRAM or Flash PCMCIA card formatted to the OP27 FAT layout.

4. Standard Transfer-Mode Entry Procedure

1. Verify the 24 V supply is OFF at the OP27 L+ and M terminals.
2. Press and hold ESC and ArrowUP simultaneously. Both keys must be physically down before 24 V is applied.
3. Apply 24 V DC. Within 2-3 seconds the LCD should display a transfer prompt with a flashing cursor.
4. Once the prompt appears, release the keys.
5. Connect the 6XV1 440-2KH cable between the PC and the OP27 IF2 port only after the transfer prompt is on screen. Hot-plugging IF2 is permitted.
6. Start the ProTool transfer: File > Download > Transfer.

5. Alternate Key Combinations for Stuck or Worn Keys

If the ArrowUP membrane is defective (a known wear item on OP7, OP17, OP27, and OP37 front foils), the standard ESC+ArrowUP sequence will not register. The OP-family bootloader accepts a second combination for panel recovery:

The erase combination is the right tool when the existing runtime has crashed and is no longer responsive to the primary sequence. After erase, the unit must be re-imaged with a PC download or memory card before any project can be loaded.

6. IF2 Cable Wiring (6XV1 440-2KH..)

The OP27 IF2 interface is a 15-pin male D-sub configured as RS-232C, DCE-style. The PC end is a 9-pin female D-sub. The official Siemens cable 6XV1 440-2KH10 implements a full null-modem with hardware-handshake bridging. Pin mapping:

The full wiring diagram and ordering data are published in the Siemens Automation Support entry Entry ID 29034071 - OP panel PC connection cable (6XV1 440-2KH..). Use this reference when building a substitute cable; do not rely on a generic DB9 extension.

7. ProTool PC-Side Configuration

1. Open the OP27 project in ProTool/Pro.
2. Menu File > Download > Transfer Settings.
3. Select the COM port assigned to the cable. On native COM1 or COM2, use the following parameters: baud 9600, data bits 8, parity None, stop bits 1, flow control RTS/CTS (hardware).
4. XON/XOFF software flow control is not supported by the OP27 bootloader. Selecting it produces a silent timeout.
5. Click Download. ProTool first negotiates firmware version. If the OP27 firmware is older than the project requires, ProTool prompts to update the firmware before downloading the project image.
6. Confirm the firmware update. The OP27 reboots once the firmware is in place and ProTool re-initiates the transfer automatically.

8. Recovery via Memory Card (No PC Required)

When the OP27 bootloader cannot be reached by any key sequence (for example, all front-panel keys are unresponsive) and the unit ships with empty flash, a PCMCIA memory card is the recovery path:

1. Format a Type I/II SRAM or Flash PCMCIA card (4 MB minimum, 16 MB maximum for the OP27) using a card reader on the PC.
2. Copy the firmware image to the card root directory. The file must be named exactly as specified in the OP27 firmware release notes (typically OP27FW.BIN or OP27FW.IMG).
3. Insert the card into the OP27 PCMCIA slot with power OFF.
4. Power on. The bootloader auto-detects the card and prompts Update firmware from card?
5. Press ENTER to confirm. The firmware loads in 30-60 seconds. The panel reboots automatically when complete.
6. After firmware is present, repeat the standard ESC+ArrowUP sequence to enter transfer mode and download the project via ProTool.

For backing up an existing project, the same card slot is used in reverse: with a card inserted, the OP27 will write a BACKUP file at every normal shutdown if enabled under System > Card Functions in ProTool.

9. IF1 vs IF2: Don't Cross the Ports

On the OP27 rear face, two D-sub connectors are present:

10. Cable Continuity Test with a Multimeter

When a substitute cable is in use and ProTool times out, validate the wiring in 60 seconds with a continuity tester:

1. With the cable disconnected at both ends, set the meter to continuity (beep) mode.
2. Verify the cross pairs: PC pin 2 to OP pin 3, PC pin 3 to OP pin 2, PC pin 7 to OP pin 4, PC pin 8 to OP pin 5.
3. Verify the handshake bridge: PC pin 4 to OP pin 6 and OP pin 8 (DTR bridges DSR and DCD at the panel end).
4. Verify the return: PC pin 6 to OP pin 20.
5. Verify the ground: PC pin 5 to OP pin 7.
6. Verify the shield: PC housing to OP housing, with no continuity to any signal pin.

Any open circuit on the cross pairs or the handshake bridge is enough to stall the transfer. The shield must not short to signal ground or the panel will reset on every PC transmit.

11. Verification

1. After the download completes, ProTool reports Transfer successful and the OP27 reboots automatically into the project.
2. Check the OP27 LCD: the project start screen should appear within 5 seconds of reboot.
3. Press a configured function key. The assigned screen or function should respond. If a tag read returns the expected value, the IF2 link is fully functional for runtime as well as commissioning.
4. In ProTool, Online > OP Diagnostics should display the OP27 firmware version and project CRC matching the downloaded file.
5. Cycle power on the OP27 with no key held. The project should start on its own. If the panel returns to "No project" or "Transfer...", the flash write was interrupted - re-transfer with a fresh 24 V supply.

12. Troubleshooting Matrix

13. Field-Proven Caveats

• The OP27 IF2 port shares its physical connector style with the IF1 MPI/PPI port. Confirm the connector count (9-pin vs 15-pin) before plugging in. The 15-pin connector is the PC link; the 9-pin is the PLC link.
• ProTool V6.0 SP2 and earlier do not support firmware update over IF2 on a brand-new OP27 with no firmware. SP3 added this capability. If a new panel will not take a transfer, upgrading ProTool to SP3 or later is the first step before opening a support request.
• When the panel is powered from the same 24 V rail as a S7-200 or LOGO!, switching transients on the supply can interrupt the bootloader handshake. Add a decoupling diode or a separate supply during the transfer window.
• The ArrowUP key on the OP27 is the membrane that wears first. A panel with a sticky or non-responsive ArrowUP will never enter transfer mode by the primary sequence. Field repair is to replace the front foil assembly.
• ProTool stores the last-used COM port in the project. If a project was last downloaded on a workstation that no longer has that COM port, the transfer fails before the cable is even queried. Re-assign the COM port in File > Download > Transfer Settings before each commissioning session.
• Some USB-RS232 adapters advertise full RTS/CTS support but tie the handshake lines to a 1 ms debounce that the OP27 bootloader rejects. A native COM port eliminates the variable.

14. ProTool Version Compatibility

15. Power and Grounding Checklist

OP27 transfer failures with no panel-side error message are frequently a power-quality issue. Confirm the following before replacing the panel:

• 24 V supply measured at the OP27 L+/M terminals is between 20.4 V and 28.8 V under load.
• The supply common (M) is bonded to panel chassis ground at exactly one point.
• The 24 V cable from the supply to the panel is < 3 m, or is sized for < 1 V drop at full load.
• No inductive loads (contactors, solenoid valves) share the same 24 V branch without a freewheeling diode.
• The PC end of the 6XV1 440-2KH cable is grounded to the same protective earth as the OP27 supply, or the PC is on a properly grounded outlet.

A ground loop between the PC and the panel is the most common cause of a transfer that starts, progresses to 12-30%, then drops the link. Floating the PC on a battery-powered laptop with the charger unplugged is a fast diagnostic.

16. Recovery Workflow Summary

1. Power off the OP27. Hold ESC + ArrowUP. Power on. Observe the LCD for the transfer prompt.
2. If no prompt, suspect a worn ArrowUP. Repeat with ESC + ArrowRight + ArrowDown to force erase, then re-attempt step 1.
3. If still no prompt, the flash is empty or corrupt. Insert a PCMCIA card with the OP27 firmware image. Power on, confirm the firmware update.
4. Once firmware is in place, repeat step 1 to enter transfer mode.
5. Connect the 6XV1 440-2KH10 cable. In ProTool, set COM port to 9600/8/N/1, RTS/CTS, and run File > Download > Transfer.
6. Verify the project start screen on reboot, then verify a tag read or function key to confirm full IF2 health.

Frequently Asked Questions