Replacing Siemens TP170B with TP177B MPI Backup, Restore

Overview: Field Scenario and Equipment Stack

The water-treatment line is controlled by a SIMATIC S7-300 CPU 313C connected over MPI to a TP170B color HMI (6AV6 545-0BA15-2AX0 family). After the TP170B panel went blank and was declared unrepairable in the field, the only spare available was a TP177B 6" color PN/DP (6AV6 642-0BA01-1AX0) pulled from a working bottle-conveyor line. Both panels are 6-inch, 256-color, 320×240 STN units, but they are not drop-in compatible at the project level because:

• TP170B projects are created in ProTool V6.0 SP2+ with the "TP170B" device integration.
• TP177B projects must be built in WinCC flexible 2004 SP2 or later (Compact/Standard), selected with the "TP177B 6" color PN/DP" device.
• TP177B supports MPI/Profibus-DP at 187.5 kbit/s and 1.5 Mbit/s and adds PROFINET, but it cannot load a compiled *.pdb/ProTool runtime image.

The migration therefore has three distinct engineering work-packages:

1. Recover the current TP177B runtime (conveyor project) so the conveyor line is not lost.
2. Create a TP177B target in WinCC flexible, migrate the original TP170B ProTool source, and compile a new runtime.
3. Get the new panel online against the S7-300 CPU over MPI, with or without routing through the PLC.

Direct communication between the PG (Siemens Field PG or laptop with PC adapter) and the HMI without the PLC in the path is possible on MPI, but only if the bus topology, baud rate, and node addresses are correct. The remainder of this reference covers that path and the alternative path (routing through the S7-300) used when the panel is already wired in the cabinet.

Prerequisites: Software, Cables, and Authorizations

Node Addressing and Bus Parameters

Confirm the following before any transfer attempt. Mismatches here are the single most common cause of "connection failure" errors when commissioning TP panels over MPI.

To change the TP177B's MPI address when the project is empty or unknown, power the panel off, hold the upper-left softkey area, power on, and enter Start > Settings > MPI/DP > Address on the touch screen (Control Panel > Transfer). Confirm "Highest Station Address" matches the PLC (default 31). Baud rate must be identical on every node.

Direct PG-to-HMI Communication over MPI

Yes, a programming device can talk to a TP17x panel directly on MPI without any PLC routing. This is the recommended path for the very first commissioning step, because it isolates the panel hardware from the rest of the bus and removes PLC routing variables from the fault list.

Wiring

1. Disconnect the TP177B's MPI/DP connector from the bus terminator and connect it to the spare Profibus connector with PG socket.
2. Insert the Siemens PC Adapter (USB A on the PG side) into the PG socket of that connector.
3. Power the PC Adapter from the USB port only when the bus is not energized; the adapter draws 5 V from USB and must NOT be on a terminated bus segment with both ends switched ON.

PG/PC Interface Assignment

1. In SIMATIC Manager choose Options > Set PG/PC Interface.
2. Select the access point S7ONLINE (STEP7) → PC Adapter (MPI) (or PC Adapter (Auto) for the USB variant).
3. Open Properties and set: MPI address = 0, Transmission rate = 187.5 kbit/s, Highest station address = 31, Timeout 30 s.

Node-Flush Test

1. Start Start > SIMATIC > STEP 7 > Accessible Nodes.
2. The TP177B should appear as TP177B 6" color PN/DP at MPI address 1 (or whichever you set).
3. If the panel does not appear, verify the bus is terminated only at the two physical ends, the shield is bonded at every connector, and the PC Adapter is seated firmly (the LED on the adapter should pulse green at 187.5 kbit/s).

Backing Up the Existing TP177B Conveyor Project

Use ProSave to pull the runtime out of the TP177B before you overwrite it. ProSave ships with both ProTool and WinCC flexible and lives in Start > SIMATIC > ProSave. It writes a single *.psb package that contains the project binary, the device image, the recipe data and (optionally) the user administration.

1. Launch ProSave. In the General tab set:
   • Device type: TP177B 6" color PN/DP
   • Connection: MPI
   • Interface: PC Adapter (MPI), 187.5 kbit/s
   • Node address: 1 (must match the panel)
2. Click Backup. Choose a target folder and a filename such as TP177B_Conveyor_2024.psb.
3. Click Start Backup. The TP177B automatically switches to Transfer mode and reboots into the loader; the progress bar in ProSave should reach 100 % within 60–120 s for a fully populated project (≈ 4 MB).
4. Verify the backup by clicking Restore on a second machine or by opening the *.psb in WinCC flexible (File > Retrieve) to confirm the project opens cleanly.

Restoring an Existing TP170B Backup onto a TP177B

You cannot flash a TP170B *.pdb runtime onto a TP177B. The device type is different and the runtime signature is rejected at boot. The supported procedure is a project migration in WinCC flexible, then a fresh download:

1. Open WinCC flexible and choose File > Migrate Project. Point it at the original ProTool *.pdb for the TP170B (the one recovered from PG/ProTool backup). ProTool V6.x projects migrate directly; older V5.x sources need a ProTool upgrade to V6 first.
2. The migration wizard re-targets the destination to the closest matching panel. Pick TP177B 6" color PN/DP.
3. Review the conversion log. Common warnings to expect on water-treatment SCADA projects:
   • "Trend view curves > 4 not supported" — TP177B supports max 4 trend curves per view.
   • "Active area for bit-triggered alarms not portable" — recable alarms in WinCC flexible bit-message config.
   • "S7 diagnostics buffer view: not supported on TP177B" — replace with the WinCC flexible "Diagnostics - System" window.
4. Set the connection parameters in Project > Transfer > Connection 1 (MPI):
   • PLC = SIMATIC S7-300 / S7-400
   • HMI station = 1, PLC station = 2
   • Baud = 187.5 kbit/s, profile = MPI
5. Build the project (Project > Compiler > All) and resolve any errors. The compile output must show "0 Errors, 0 Warnings (treated as error)".
6. Connect the PG to the panel as described in Section: Direct PG-to-HMI Communication over MPI.
7. In WinCC flexible choose Transfer > Transfer > MPI/DP and click Transfer. Accept the prompt to overwrite the runtime. The panel reboots, the loader receives the runtime, and the panel switches to online mode against the water-treatment S7-300.

Routing Through the S7-300 (PG → PLC → HMI)

When the TP177B is already wired to the bus and the cabinet is live, it is often simpler to leave the bus in place and route through the CPU. This is the option Siemens describes in FAQ 2383206 — Routing S7 connections and OP connections.

NetPro Configuration

1. Open the S7 project in SIMATIC Manager.
2. Launch Options > NetPro.
3. Verify the topology: PG (MPI, addr 0) → S7-300 MPI subnet → TP177B (MPI, addr 1). The HMI must appear as an "OP" station on the same MPI subnet as the CPU.
4. Open the OP station properties, set MPI address = 1, slot = 3 (TP177B always uses slot 3), and assign it to the S7-300 connection you intend to route through.
5. On the CPU station, double-click the MPI interface and confirm the address (2 by default) and that the subnet is flagged "Activated".
6. Click Save and Compile (NetPro toolbar) and answer Compile and Check All. Resolve any errors (typically a missing slot or an OP without an S7 connection).
7. Click Configure Network (the toolbar button with the download arrow) to push the routing tables down to the S7-300. The CPU must be in STOP or RUN-P; you will be prompted.

WinCC flexible Routing Bit

1. Open the migrated project in WinCC flexible.
2. Go to Project > Transfer > Settings and tick Enable routing.
3. Set the transfer channel: MPI/DP → "S7 routing via PLC".
4. Start the transfer. WinCC flexible will handshake with the S7-300 first, then route the runtime blocks to the TP177B at MPI address 1 over the existing bus.

Verification Procedure

1. Node visibility: In SIMATIC Manager → Accessible Nodes, both the S7-300 (addr 2) and the TP177B (addr 1) must be listed with no warning triangles.
2. Tag test: In WinCC flexible → Project > Compiler > Start Runtime, simulate the project on the PG against the live S7-300. Toggle a known output (e.g. raw-water pump starter) and confirm the HMI button reflects the change within one bus cycle (≤ 1 s at 187.5 kbit/s).
3. Alarm test: Force a low-level digital input and confirm that the configured alarm appears in the HMI message view with timestamp and status text.
4. Recipe test: If the original TP170B used recipes, write a known set, then read it back; the value table must be byte-identical.
5. Restart test: Power-cycle the panel cold. The runtime should boot to the configured start screen in < 25 s and re-establish the MPI connection automatically.
6. Routing rollback: If the panel was originally commissioned with ProTool, confirm the converted project does not contain a leftover "PROFIBUS-DP" master on the wrong subnet — a common source of bus errors after migration.

Troubleshooting Matrix

Edge Cases and Field-Proven Caveats

• TP170B color vs TP170B mono: Confirm the original is the color variant (6AV6 545-0BA15) before migration. The mono variant uses a different color palette and the converter will warn, but may not block the migration.
• CPU 313C integrated I/O: If the project uses the on-board digital and analog I/O, verify the area-pointer configuration in WinCC flexible (default: Inputs 0…7, Outputs 0…7). TP177B does not support area pointers to the integrated counters (slot 0) — only to the standard PII/PIQ ranges.
• Multi-language text: The ProTool → WinCC flexible converter preserves all configured language databases. Confirm font availability on the TP177B (only Siemens fonts: Arial, Tahoma, Courier ship with the runtime).
• Passwords and user administration: TP170B used a 4-digit numeric password; TP177B supports alphanumeric passwords up to 24 characters. Document the original PIN before migration, otherwise you will be locked out of the user admin when commissioning the new panel.
• Time synchronization: TP177B can act as the time master on MPI, but the S7-300 313C does not have a battery-backed clock on all variants. Set the time to "PLC time" in Project > Time Synchronization to avoid a 1970s-timestamp problem on long power-downs.
• OS update compatibility: TP177B 6" color PN/DP images are: V1.0.0, V1.1.0, V1.1.2, V1.1.4. WinCC flexible 2008 SP3 supports images up to V1.1.4. Older WinCC flexible (2005 SP1) caps at V1.1.0. Match your WinCC flexible version with the panel image before commissioning.

Documentation References

• Siemens Support entry 2383206 — "How do you configure routing for an OP connection through an S7-300/400 CPU?" Siemens ID 2383206
• SIMATIC HMI TP177B device manual (6AV6 642-0BA01-1AX0) — Manuals for TP177B
• WinCC flexible migration cookbook — ProTool/Pro to WinCC flexible migration
• SIMATIC S7-300 CPU 313C manual — CPU 313C manual
• ProSave V6.0 SP2 user guide — bundled with ProTool V6.0 and WinCC flexible installations

FAQ