TP170A to TP177A Migration: Siemens HMI Device Change Reference

TP170A to TP177A Migration: Siemens HMI Device Change Reference

1. Overview and Scope

This reference documents the engineering steps required to port an existing WinCC Flexible / TIA Portal project from a Siemens SIMATIC TP170A operator panel to a TP177A (or the reverse direction) by changing the device type inside the configuration software. The scope covers hardware differences, configuration-side limits (tag count, screen count, recipes, archives, scripts), the device-change procedure in WinCC Flexible, the serial/parallel / PROFIBUS download mechanics, and the field-verification checklist used to confirm a successful migration.

The two panels share the same physical footprint (5.7" STN LCD, 320 × 240 pixel QVGA, 4 membrane function keys, MPI/PROFIBUS DP-12 connector), which is why they are commonly field-swapped when the spare inventory is mixed. The runtime behavior, however, is defined by the firmware-loaded image, and that is where engineering attention is required.

2. TP170A vs TP177A Hardware Matrix

The following table compares the two devices against the parameters most often cited in a maintenance-engineering change-out. Where the manufacturer datasheet quotes a range (firmware-dependent), both values are listed.

3. WinCC Flexible System Limits Comparison

The single most authoritative source for the runtime capacity of each panel is the WinCC Flexible help system under System Limits. The values below are reproduced from the WinCC Flexible 2008 SP3 reference; always re-validate against the help system of the exact SP used to compile the project, because Siemens revises these numbers between Service Packs.

4. Prerequisites for a Device-Type Change

Before opening the project in WinCC Flexible and changing the panel designation, confirm the following prerequisites. Missing any one of these typically surfaces later as a runtime fault or a non-compiling project.

1. Engineering workstation install – WinCC Flexible 2008 SP3 or later, with the TP170A and TP177A option packages installed. The TP177A target is selectable from WinCC Flexible 2005 onward; the TP170A target is retained as a legacy option for maintenance migrations.
2. Project archive – Always work from a clean backup copy. Open the original .hmi or .fwx project, then use File → Save As with a new name to create the migration working copy.
3. Firmware image compatibility – Both panels load their image over MPI/PROFIBUS or via the PC adapter. Confirm the destination panel carries a firmware revision equal to or newer than the one referenced by the new project. Use ProSave or the TIA Portal Online → Accessible Nodes dialog to read the device article number and firmware version before any transfer.
4. Configuration cable – For the TP170A use the Siemens PPI/MPI cable (6ES7 901-3CB30) or USB-to-MPI adapter (6ES7 972-0CB20-0XA0). For the TP177A either RS-232 or USB is supported depending on the build variant.
5. PLC connection profile – The MPI/PROFIBUS address and baud rate configured in the project must match the physical bus. The TP177A defaults to address 1, baud 1.5 Mbps; the TP170A defaults to address 1, baud 187.5 kbps. Mis-match is the single most common reason a freshly downloaded project fails to connect.
6. Password and recipe storage – Recipes on TP170A reside in internal flash with limited write-cycle endurance (typically 100k cycles). If the migrated project contains heavy recipe logging, audit the write frequency before committing to the TP177A target because the runtime image is flash-backed in both panels.

5. Step-by-Step Device-Type Change in WinCC Flexible

The conversion workflow below assumes the project is being moved from a TP177A target down to a TP170A target (the direction typically forced by hardware replacement). The reverse direction (TP170A → TP177A) follows the same steps; the only differences are the device-selection entry and a typically easier limit headroom.

5.1 Open the project and inspect current limits

1. Launch WinCC Flexible and open the project archive created in step 4.2 above.
2. From the project tree, right-click the panel node and choose Device Properties. Note the current target device, firmware version, and MPI/PROFIBUS address.
3. Open Help → System Limits for the current device. Export the limit report to a text file for comparison with the destination panel.

5.2 Select the new target device

1. Right-click the panel node in the project tree and choose Change Device….
2. In the device-selection dialog, navigate to TP170A → 6" Mono (or the specific article number that matches the spare unit) and confirm.
3. WinCC Flexible will display a warning if any object in the project exceeds the destination panel's system limit. Record each warning; these are the objects that must be edited or removed before the next compile.

5.3 Resolve limit violations

For each violation returned by step 5.2:

5.4 Verify the MPI/PROFIBUS connection profile

1. Open Connections in the project tree and confirm the HMI station address.
2. For TP170A, the default Baud rate = 187.5 kbps and Address = 1 are typical. For TP177A the default Baud rate = 1.5 Mbps.
3. Set the parameters to match the spare unit. Use the physical address rotary switches on the back of the panel; do not rely solely on the project setting.

5.5 Compile the project

1. Select Project → Compile → All (Rebuild). This forces a full regeneration of the runtime image and is required after a device-type change.
2. Inspect the Output window. A clean compile ends with *** Compile completed, no errors ***.
3. If warnings are present related to system limits, iterate back to step 5.3.

5.6 Transfer the runtime to the panel

1. Connect the PC adapter to the panel's MPI/PROFIBUS port.
2. Set the panel to Transfer mode (TP170A: Control Panel → Transfer; TP177A: Start Center → Transfer).
3. In WinCC Flexible select Project → Transfer → Transfer. The dialog must show Transfer mode: MPI/DP and the correct interface (e.g. PC Adapter (MPI)).
4. Click Transfer. ProSave / WinCC Flexible will erase the destination image, write the new project, and reboot the panel.

6. Functional Differences That Persist After a Device Change

Several functional behaviors do not appear in the limit table but differ between the two panels and must be validated by the commissioning engineer.

6.1 Color rendering

The TP170A renders only blue mode (4 grayscale levels mapped to blue). A project authored for the TP177A's 256-color palette will be auto-down-sampled by the runtime when loaded onto a TP170A, but bitmap graphics originally rendered with subtle color gradients may appear as flat blocks. The workaround is to author bitmap graphics in grayscale from the start, or accept the visual degradation on the spare unit.

6.2 Touch behavior

The TP177A color variant has a resistive touch overlay; the TP170A does not. If the original TP170A project was authored using only function keys, the TP177A will accept the project unchanged. If the project was authored for a TP177A and uses touch-only buttons, the TP170A will not be able to actuate those buttons because there is no touch input. Always re-author touch-only buttons as function-key buttons before migrating down to the TP170A.

6.3 Alarm acknowledgement

The TP170A's alarm window supports acknowledgement via the ACK key on the function-key strip and via the on-screen ACK button. The TP177A additionally supports a dedicated ACK event when the same key is pressed twice. Behavior is identical in practice, but if the project uses the double-ACK event (TP177A-only property), it must be remapped to single-ACK before the down-migration.

6.4 Time and date formats

Both panels store the date/time in BCD format over the MPI/PROFIBUS link, but the TP177A additionally accepts a settable 12-hour format. If the original project is configured for 12-hour display, the TP170A will silently fall back to 24-hour display; check the runtime log on the spare unit to confirm the operator's expectations are still met.

6.5 Function-key labeling

The TP177A exposes soft-key labels configurable from inside the runtime. The TP170A strips are physical membrane keys with printed legends. If the spare TP170A has different legend strips than the production panel, the migration must be accompanied by a printed key-cap exchange or a laminated overlay to maintain operator familiarity.

7. Memory and Image-Size Budget

The flash memory layout on the two panels differs slightly, so a project that compiled cleanly on the TP177A may fail on the TP170A not because of logical limit violations but because the generated runtime image is larger than the destination flash. The figures below are derived from the WinCC Flexible 2008 SP3 release notes.

If the regenerated image exceeds the destination budget, the compile will fail with error 0x8004xxxx "Image exceeds device memory". Remedies in order of effectiveness:

1. Reduce bitmap resolution to 16-bit (5-6-5) and re-import; this typically recovers 20-30% of bitmap cache.
2. Move large bitmaps into the PLC and reference them via a tag that selects the file name.
3. Split the project into two complementary parts using the WinCC Flexible Segmented Project feature (TP177A only).

8. Download Topology and Cable Pinout

The MPI/PROFIBUS connector on both panels uses a Siemens-proprietary D-sub-9 pinout (PG/PC interface). The standard PC adapter cable 6ES7 972-0CB20-0XA0 converts to USB on the workstation side. Pin mapping for the field-side connector (looking at the panel's female D-sub-9):

Termination on the bus must remain active at both physical ends. The TP170A and TP177A do not provide bus termination; if the spare panel is at the end of the segment, insert an external PROFIBUS terminator (6GK1 500-0EA00) between pins 3 and 8, with the 390 Ω/220 Ω/390 Ω bias network.

9. Verification Checklist

After the device-type change and the image transfer, walk through the following checklist on the spare unit before commissioning the line.

1. Image boot – Panel powers up to the configured start screen within 20 seconds (TP170A) / 15 seconds (TP177A).
2. Communication link – Status icon at the top-right shows a green link to the PLC. Use Control Panel → Diagnostics on the panel to read the MPI/PROFIBUS error counter; it must remain at 0 for 60 seconds of operator activity.
3. Tag update – Force a bit in the PLC and verify the corresponding tag indicator on the screen toggles within one configured update cycle (default 1 s).
4. Alarm window – Trigger a low-priority alarm and confirm it appears in the alarm line with the configured ACK behavior.
5. Recipe round-trip – Save the active recipe to the panel, power-cycle the panel, reload the recipe, and verify all element values are intact.
6. Time / date – Confirm the date/time propagated from the PLC or the panel's RTC matches UTC within ±1 minute.
7. Function-key mapping – Press each function key and confirm the configured action fires. If the spare TP170A has a different legend strip than the production TP177A, document the mismatch and apply a printed overlay.
8. Touch behavior (TP177A target only) – Tap each on-screen button and confirm the press event triggers.
9. User authorization – Log in at each user level and confirm the configured rights are enforced. The TP177A can hold up to 32 user views; the TP170A supports only 8, so consolidation is required if migrating down.
10. Backlight timer – Confirm the backlight timeout fires (TP170A default 60 min, TP177A default 240 min) and recovers on operator input.

10. Troubleshooting Matrix

11. Field-Proven Caveats

• Spare unit firmware must be ProSave-compatible. If the spare TP177A was decommissioned years ago with an old image, ProSave will still write the new project, but the panel's on-board RTC may not be backed up. Set the date/time during commissioning.
• Retention of operator passwords. When the panel is erased before the new image transfer, all user passwords are wiped. Reissue the operator list at handover.
• Color profile drift between production and spare. If the production line runs on a TP177A and the spare is a TP170A, expect visual differences on status indicators. Communicate the difference to operations before the swap.
• 24 V supply current. Both panels draw approximately 0.24 A at 24 V. The existing PSU in the cabinet will tolerate the swap with no rework required. Verify the PSU derating at 40 °C if the cabinet ambient is high.
• MP377 / TP277 not covered. This document covers only the TP170A / TP177A generation. Migration to the 6" or 10" Comfort panels requires a project rebuild, not a device-type change.

12. Reference Resources

The following official Siemens manuals and entries provide the underlying engineering detail used to compile this reference. Engineers performing a TP170A ↔ TP177A migration should consult them directly to validate version-specific limits.

• SIMATIC HMI TP170A / TP170B Operating Instructions
• SIMATIC HMI TP177A / TP177B Operating Instructions
• WinCC Flexible 2008 System Manual – System Limits
• ProSave Service Tool User Manual
• WinCC Flexible Migration Guide (TP170A → TP177A)

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