Connecting Siemens SIMATIC TP170A to PC: MPI Cable Setup Guide

Overview of the SIMATIC TP170A

The SIMATIC TP170A is a legacy 5.7-inch operator panel from the SIMATIC HMI product line, released in the late 1990s alongside the TP170B and OP170 families. It belongs to the first generation of Siemens touch panels built around the ProTool/ProTool/Lite and WinCC flexible Compact configuration environments. Although superseded by the TP177A and ultimately by the Comfort and Unified panels, a large installed base of TP170A units is still in service worldwide, and field engineers routinely need to commission, recover, or replicate projects on these devices.

The TP170A ships with an integrated MPI/DP interface on the rear of the unit. This interface is the same physical connector as PROFIBUS-DP, terminated on a 9-pin sub-D socket. The panel also exposes an RS-232, an RS-422, and an RS-485 interface internally for use by the configuration engineer when downloading via serial cable, although the dominant commissioning path in the field is MPI.

Two configuration software streams cover the TP170A:

• ProTool / Lite, Version 5.2 SP1 or higher - the original Siemens tool for the OP/TP 170 series.
• WinCC flexible Compact, Version 2004 or higher - the successor tool that maintains compatibility with the TP170A.

Both tools target the same runtime firmware on the panel; a project authored in either package can be transferred to the TP170A as long as the runtime image is the same generation. The panel is not supported by the TIA Portal. Attempting to add a TP170A inside TIA Portal V13 or later will not yield a usable device entry; only the TP177A appears in the TIA Portal catalog for this form-factor family. Projects originally written for TP170A must remain in ProTool or WinCC flexible Compact.

MLFB Identification and Hardware Variants

Before any connection work, identify the panel by its MLFB (Siemens order number). The TP170A family is identified by the prefix 6AV6. The most common variant encountered in the field is:

Confirm the exact MLFB by reading the rating plate on the rear of the panel, or by retrieving the device from the product catalog at the official Siemens Industry Support page for the TP170A (ID 4297764). The full ordering data is also obtainable from the current ST80 catalog referenced in the original release notice.

The key electrical and protocol interfaces for the TP170A Blue Mode STN display (6AV6545-0BA15-2AX0) are:

Message and alarm handling limits inside the panel runtime are fixed by firmware and must be observed when authoring or restoring projects:

These limits are derived directly from the panel's technical data sheet and must be enforced by the configuration tool. WinCC flexible Compact 2004 will refuse to compile a project that exceeds them.

Prerequisites - Hardware and Software

Before connecting the TP170A to a PC, gather the following items.

Hardware

1. MPI/DP PC Adapter - either the legacy PC Adapter USB (6ES7972-0CB20-0XA0) for modern PCs, or the older RS-232 PC Adapter (6ES7972-0CA23-0XA0) for serial hosts.
2. PROFIBUS cable with two 9-pin sub-D connectors, terminated according to PROFIBUS-DP rules. A standard purple PROFIBUS cable (6XV1830-0EH10) is acceptable.
3. PROFIBUS terminating resistor if the TP170A is at one end of the segment and no other device is present.
4. 24 VDC power supply rated for at least 0.5 A continuous, capable of supplying the TP170A (typical consumption 24 V / 0.3 A).

Software

1. ProTool / Lite Version 5.2 SP1 or higher, or
2. WinCC flexible Compact Version 2004 or higher (commonly WinCC flexible 2008 is used because it is the last release that retains the TP170A device entry).
3. ProSave - bundled with both ProTool / Lite and WinCC flexible, located in the installation directory (typically C:\Program Files\Siemens\ProTool or C:\Program Files\Siemens\WinCC flexible). ProSave is the dedicated service tool for backup, restore, and OS update of legacy panels.
4. S7-PCT (Port Configuration Tool) is not required for MPI transfers; it is needed only for PROFINET-based panels.

Selecting the MPI/DP PC Adapter Cable

The TP170A speaks MPI/PROFIBUS-DP at speeds up to 1.5 Mbit/s on its RS-485 port. The PC side needs an adapter that bridges between USB or RS-232 and PROFIBUS. The two practical choices are:

Set the PC Adapter's MPI address to 0 (default) and MPI baud rate to 187.5 kbit/s if the panel and any other devices on the bus are unknown. The TP170A supports baud rates of 19.2, 187.5 kbit/s, 1.5 Mbit/s; 187.5 kbit/s is the universally safe choice for first contact.

Pinout Reference for the TP170A Serial Ports

The MPI/DP port on the TP170A rear is a 9-pin sub-D female socket, PROFIBUS-DP standard pinout:

The RS-232 port (where fitted on the TP170A configuration variant) follows standard DCE pinout with TxD on pin 2, RxD on pin 3, and signal ground on pin 5.

Configuring the Connection in ProTool / Lite V5.2 SP1

1. Install ProTool / Lite Version 5.2 SP1 from the original Siemens CD or the ProTool V6.0 / STEP 7 package that bundles it.
2. Open the ProTool CS (Configuration Studio) and select File > New. Pick TP170A from the device catalog.
3. Open System > Target & System Settings > Connection and choose the MPI transfer channel.
4. Set the HMI station MPI address. The factory default for the TP170A is 1. Leave it at 1 unless the bus master already uses that address.
5. Set the baud rate to 187.5 kbit/s for the first transfer.
6. Click Save & Compile to generate the *.pwl or compressed runtime image.
7. Open File > Transfer > Settings. Select the PC Adapter type (USB or COM) and the corresponding MPI/DP address of the PC Adapter (default 0). Confirm baud rate 187.5 kbit/s.
8. Click Transfer. ProTool will prompt for the panel's MPI address - enter 1.

If the transfer succeeds, ProTool will report Transfer completed successfully and the panel will reboot into the new project. A failure usually indicates either a wiring problem, mismatched baud rates, or the panel not being in transfer mode (see next section).

Configuring the Connection in WinCC flexible Compact 2004

WinCC flexible Compact 2004 (and later WinCC flexible 2008) is the recommended configuration tool on a modern PC. The TP170A device entry is still selectable in WinCC flexible 2008 under the Devices & Networks catalog of the older WinCC flexible Engineering Station. Proceed as follows:

1. Open WinCC flexible ES and create a new project. Select device TP170A from the catalog.
2. Open Project > Transfer > Transfer Settings. Under Mode, select MPI/DP.
3. Configure the PG/PC Interface by clicking Select.... Choose the access point S7ONLINE and the interface parameterization PC Adapter (MPI) or PC Adapter (PROFIBUS).
4. Verify the MPI address of the PC Adapter is set to 0 and the HMI station address is set to 1. Higher baud rates up to 1.5 Mbit/s can be selected once communication is established.
5. Compile the project: Project > Compiler > All. Resolve any errors before attempting transfer; common warnings about unsupported Visual Basic scripting constructs can be ignored if the panel profile disables those features.
6. Start the transfer: Project > Transfer > Transfer to Device. WinCC flexible will scan for the panel and prompt before overwriting.

If you receive Cannot reach target station, the panel is either not in transfer mode, the MPI cable is miswired, or the PC Adapter driver has not been installed. Refer to the troubleshooting matrix below.

Activating Transfer Mode on the TP170A

The TP170A must be placed into transfer (download) mode before the PC can push a project to it. There are two ways to do this:

1. Automatic transfer (recommended): When the TP170A is idle (no project running or project is in stop mode), briefly touch the screen in an empty area. The system menu appears. Navigate to Transfer and enable Automatic. The panel will then accept any incoming transfer without further user action for a window of approximately 60 seconds.
2. Manual transfer: Power-cycle the panel. During the boot sequence, a transfer prompt is shown. Confirm Transfer to enter transfer mode immediately.

Transfer mode is indicated on the panel by a message such as Transfer mode active - waiting for project and the MPI LEDs flashing. The panel will stay in this state until either a project is received or it is manually exited.

Performing a ProSave Backup and Restore

Because upload is not possible, backup is the only safety net for a TP170A. Use ProSave, bundled with both ProTool / Lite and WinCC flexible Compact.

Backup Procedure

1. Connect the PC to the TP170A via MPI as described above. Confirm the panel is in transfer mode.
2. Launch ProSave from the Start menu (Siemens Automation > ProSave).
3. Select the device type TP170A.
4. Set the connection to MPI, with the PC Adapter on S7ONLINE and the panel at address 1.
5. Click Backup. ProSave will read the panel's internal flash and create a backup file of type *.psb (ProSave Backup).
6. Specify a destination directory and file name. Store multiple generations; do not overwrite the only copy.

Restore Procedure

1. Connect the panel as above. Place it in transfer mode.
2. Open ProSave, select TP170A, MPI, address 1.
3. Click Restore and select the desired *.psb file.
4. Confirm the overwrite prompt. The panel will reboot into the restored project when the transfer completes.

Operating System (Firmware) Restore

If the panel's internal image becomes corrupted (for example, after an interrupted download), ProSave can also reinstall the operating system:

1. Open ProSave, select TP170A, MPI.
2. Switch to the OS Update tab.
3. Select the firmware file shipped with ProTool or WinCC flexible (typically TP170A.im_ or similar in the panel images directory).
4. Click Update OS. The panel may reboot multiple times during this procedure.

Critical Limitations - Upload, TIA Portal Compatibility, Legacy Mode

No Project Upload

The TP170A runtime does not support reverse transfer of a compiled project to a PC. This is a firmware-level decision by Siemens and is independent of the configuration tool. Engineers who need to clone a TP170A must either:

• Re-create the project in ProTool / Lite or WinCC flexible Compact from documentation.
• Replace the failed TP170A with an identical MLFB and restore the ProSave backup to the new panel.

Not Supported in TIA Portal

The TP170A does not appear in the TIA Portal device catalog. The successor panel TP177A is the entry point for TIA Portal projects in this form-factor family. A project authored for TP170A cannot be migrated automatically to TIA Portal; engineers must rebuild screens, tags, and alarms. Plan a migration path if TIA Portal standardization is a project requirement.

WinCC (TIA Portal) Functionality Caveats

Even when the TP170A is mentioned in cross-reference material for WinCC TIA Portal libraries, the actual usable functionality is restricted:

• Visual Basic Scripts: supported in editor, no simulator debugging.
• Task planner: not supported.
• Help system: not supported.
• Number of characters per info text: 0 (no info text available).
• Number of tooltips: 0 (no tooltips).

These limitations must be respected when authoring projects intended for the TP170A, even when working in modern WinCC engineering environments.

Troubleshooting Matrix

Verification Checklist

Before leaving site after a TP170A transfer, run through the following checks:

1. The new project is visible on the panel after the panel reboots automatically.
2. All configured tags resolve correctly (no "address error" indicators).
3. Bit-message alarms are received from the PLC at the configured trigger bits.
4. The acknowledgement group behavior matches the project specification.
5. A ProSave *.psb backup of the new project is saved to at least two physical media.
6. The PC Adapter is disconnected and the MPI bus is re-terminated if the panel was an end node.
7. The original engineering project file (the *.pwl for ProTool or the *.hmi for WinCC flexible Compact) is archived in the project documentation system, with version comments and date.

Field-Engineering Notes and Best Practices

• Always commission a TP170A from a known-good engineering source. Because upload is impossible, recovering a misconfigured panel without a backup is essentially impossible without rebuilding the screens from paper documentation.
• Maintain a physical inventory of replacement TP170A panels with MLFB 6AV6545-0BA15-2AX0 for hot-swap replacement. Verify the OS version of the spare matches the running plant before deployment; an OS mismatch can prevent a ProSave restore from succeeding.
• When connecting to a multi-master MPI bus, ensure the TP170A MPI address (default 1) does not collide with an S7 CPU, an OP, or another TP. Address conflicts manifest as intermittent transfer failures and unexplained bus errors.
• Document the project's WinCC flexible or ProTool version inside the project properties. If the project needs to be edited in five years, the toolchain version determines whether the original project will still open.
• For migrating to a newer platform, use a TP177A or a Comfort panel as the replacement target and rebuild the screens. A direct import from TP170A source to TIA Portal is not supported.