1. Problem Overview
The Siemens OP170B operator panel is a compact text/graphics HMI from the 170-series family. It is commonly encountered in legacy installations that are migrated, replaced, or recommissioned on newer engineering PCs. Engineers performing this migration typically use ProTool/Pro CS V6.0 SP3 (or later SPs) on Windows XP/2000 to download a project that was originally created in an earlier ProTool release.
Two distinct failure modes appear during this workflow:
- Version-compatibility prompt at file open or transfer, warning that the project was last saved in an older ProTool version and that a forward save will block re-edit on the original tooling.
- Communication failure between the OP170B and the S7 PLC (for example a CPU 315-2DP behind a CP 343-5), typically producing a Project data being synchronized (Open) cannot be routed to the required communication peer error or a Could not establish connection message during download.
Both symptoms can be caused by mismatched PG/PC interface assignments, wrong MPI node addresses, an inactive serial transfer channel on the panel, or a stale CP5511 PC adapter driver. This reference walks through the diagnostic path and the field-proven corrections.
2. Affected Components and Versions
| Component | Version / Catalog Reference | Notes |
|---|---|---|
| OP170B operator panel | 6AV3 617-1JC20-0AX0 (mono) / -1KC20 (color) | RS-232 on Sub-D, MPI on Sub-D, no USB |
| ProTool/Pro CS | V6.0 SP3 and later SPs up to SP5 | Last release line; superseded by WinCC flexible 2004+ |
| ProSave | bundled with ProTool/WinCC flexible | Required for OS update and backup/restore |
| PC adapter USB | 6ES7 972-0CB20-0XA0 | For MPI/DP transfer when serial is unsuitable |
| PC adapter PCMCIA | CP 5511 / CP 5512 (6GK1 551-1AA00) | Legacy MPI interface, sensitive to driver state |
| PLC family | S7-300 with CPU 315-2DP, CP 343-5 | DP/MPI separation requires correct peer selection |
Confirm the panel firmware and ProTool SP before troubleshooting; the OP170B manual is published at Siemens Support Entry ID 1838350 (Transfer Settings are described on page 3-9 of the device manual).
3. Symptom Matrix
| Symptom | Probable Cause | First Action |
|---|---|---|
| "Configuration edited in an earlier version of ProTool" warning | Project source from older ProTool/Pro | Decide on forward save; back up .pdb/.fwd first |
| "Project data being synchronized cannot be routed to the required communication peer" | Peer (PLC) selection in ProTool does not match the panel's active channel | Verify Channel 2 on OP is enabled and remote-control flag is set |
| "Could not establish connection" after 10-15 s | PG/PC interface address conflict or wrong bus profile | Set PG/PC MPI address to 0, highest station 31, baud 187.5 kbps |
| Diagnostic lists addresses 0, 2, 3 but not 1 (the OP) | OP not yet active on the bus or wrong address set in panel | Re-check OP MPI address in Control Panel > Transfer > MPI |
| CP5511 cannot be installed | Driver stuck in Plug&Play hold or maximum instance count reached | Uninstall CP5511 in Device Manager, reboot, let PnP re-detect |
| Compile error persists after fixing peer | Symbol list bound to wrong MPI network or wrong controller | Re-select "Choose a communication peer/symbol list" |
| OS update over serial works, project transfer fails | Wrong cable (null-modem vs. point-to-point translator) | Use a true MPI cable, not a plain RS-232 null-modem for MPI |
4. Pre-Transfer Checklist
Run this verification list before any project transfer attempt. Each item blocks at least one documented failure mode.
- Back up the existing OP170B image with ProSave (File > Backup > Serial/MPI/USB) to a known-good directory.
- Verify the engineering PC has the latest ProTool/Pro SP for the installed base version. A mixed environment (for example ProTool V6.0 SP2 source + SP3 target) is the most common trigger for the version warning.
- Open Control Panel > PG/PC Interface and confirm the access point of the S7ONLINE interface. The same access point must be referenced by the ProTool transfer dialog.
- Inspect the physical cabling: serial transfer uses a point-to-point RS-232 cable (PC COM ↔ OP COM), while MPI/DP transfer uses a Profibus cable with Profibus connectors (for example 6ES7 972-0BA12-0XA0) and terminating resistors ON at both ends only if the OP and PLC are the bus terminators.
- On the OP170B itself, navigate to Control Panel > Transfer and confirm that Channel 2 (MPI) or Channel 1 (Serial) is enabled and the Remote Control flag is set.
- Note the OP's MPI address, baudrate, and highest station address. The default MPI address of an OP170B out of the box is 1.
5. Resolving the Version-Compatibility Warning
The prompt "This configuration was edited in an earlier version of ProTool the last time it was edited. If it is saved with the current version it will no longer be possible to open it with the earlier version of ProTool" is informational, not a fault. It is raised by every ProTool version that loads a project whose embedded version stamp is older.
- If the original ProTool version is still required for parallel editing, click Cancel, copy the project, and only forward-save the copy.
- If the engineering workflow is single-tool, accept the prompt, recompile, and store the updated
.fwdin the controlled backup location. - After recompile, transfer with the new
.fwd. The OP170B does not embed the source version, so the panel side has no version lock; only the PC side does.
.pdb on offline storage before confirming the prompt.6. Serial (COM Port) Transfer Configuration
Serial transfer is the simplest path for a single-panel OS update or small project. It is also the most tolerant of MPI/DP wiring issues because it does not use the Profibus stack.
6.1 Cable pinout (OP170B COM to PC COM)
| PC DB-9 male | OP170B DB-9 male | Signal |
|---|---|---|
| 2 | 3 | TxD ↔ RxD |
| 3 | 2 | RxD ↔ TxD |
| 5 | 5 | GND |
| 4 + 6 bridged | 4 + 6 bridged | DTR/DSR loopback |
| 7 + 8 bridged | 7 + 8 bridged | RTS/CTS loopback |
Do not use this cable for MPI/DP transfer. For MPI, a Profibus segment with a Profibus connector on the OP side is required, even when the OP is the only Profibus node.
6.2 ProTool transfer settings
- In ProTool: File > Download > Preferences.
- Select Serial as the transfer channel.
- Set the COM port to match the engineering PC (typically COM1).
- Set baudrate to 115200 bit/s for OP170B (auto-negotiates down to 19200 if needed).
- Tick Remote Control on the OP before pressing the transfer icon.
6.3 OS update over serial
If the panel is new (factory image only), perform the OS update first with ProSave:
- Start ProSave, select OP170B as the target device, Serial as the connection, choose the COM port.
- Under Update OS, browse to the matching
.imgfile shipped on the ProTool installation DVD. - Activate Remote Control on the panel and start the update. A complete OS update typically takes 4-8 minutes.
- After the panel reboots, proceed with the project transfer from ProTool.
7. MPI Transfer Configuration
MPI is the standard production transfer medium. It supports runtime online operation and download, but it requires correct addressing on three actors: the OP170B, the PLC (or CP behind the PLC), and the PG/PC interface.
7.1 OP170B MPI parameters
Open Control Panel > Transfer > MPI on the panel and apply the following baseline:
| Parameter | Value | Comment |
|---|---|---|
| Channel | Channel 2 enabled | Channel 1 reserved for serial |
| Remote Control | Enabled | Allows host-triggered transfer |
| MPI address | 1 | Default for OP170B; must be unique on the bus |
| Highest station address | 31 | Default; matches standard MPI |
| Baudrate | 187.5 kbps | Default MPI baudrate |
| Timeout | 10 s | Used by panel to retry passive tokens |
| Bus master mode | Panel is only master on the bus (or OFF if PLC is master) | Match to PLC configuration |
7.2 PG/PC interface settings
On the engineering PC, open Control Panel > PG/PC Interface and select the access point used by ProTool (default S7ONLINE):
| Parameter | Value |
|---|---|
| Interface parameterization | PC Adapter (MPI) or CP 5511 (MPI) |
| PG/PC is the only master on the bus | Enabled (only if no other master exists) |
| PG/PC MPI address | 0 |
| Timeout | 10 s |
| Baudrate | 187.5 kbps |
| Highest station address | 31 |
Press Diagnostics; a healthy bus lists the active nodes including the OP at address 1 and the PLC/CP at its configured address. If address 1 is missing, the OP is not actively on the segment; check connectors, terminator power, and the panel's Transfer enable.
8. Communication Peer Configuration in ProTool
The peer selection inside the ProTool project is the single most common source of the cannot be routed to the required communication peer error. The peer must reference the same MPI network and the same logical PLC station the panel can actually reach on the bus.
- In ProTool, open the project and go to Controllers.
- Right-click the controller (for example
PLC_1) and open Properties. - Open the Parameters tab and click Choose a communication peer/symbol list.
- From the dropdown, select the MPI network that physically contains the target PLC. If the S7-300 is on a Profibus segment via a CP 343-5, select the CP 343-5 as the peer, not the CPU 315-2DP directly, because the OP only sees the CP on the bus.
- Confirm peer parameters:
| Field | Typical value (CP 343-5 in slot 2, rack 0) |
|---|---|
| Peer MPI address | 3 |
| Expansion slot | 2 |
| Rack | 0 |
| Cyclic operation | Yes |
| OP address | 1 |
| Bus role | Only master |
- Save, recompile, and retransfer the project.
9. Resolving CP5511 Driver Issues
The CP 5511 (PCMCIA) and its USB sibling, the PC Adapter USB (6ES7 972-0CB20-0XA0), are highly sensitive to the Windows Plug&Play state. After multiple driver updates, hot-unplugs, or a Windows image rollback, the device may refuse to install with: A displayed interface cannot be installed if it is on a Plug&Play module, or the maximum number of interfaces of this type are already installed.
9.1 Clean reinstall procedure
- Shut down the PC and physically remove the CP 5511 (PCMCIA) or unplug the PC Adapter USB.
- Boot into Windows, open Device Manager, and uninstall any instance of PC Adapter (MPI) / CP 5511, including the hidden devices (View > Show hidden devices).
- Delete the lower/upper filter entries under the device properties > Details > Service if present.
- Reboot without the adapter. Confirm that no ghost instance appears.
- Power down, insert the CP 5511 / connect the USB adapter, and let Windows detect and install the driver.
- Re-open PG/PC Interface; the CP 5511 should now be selectable.
9.2 When reinstall fails
If the maximum-instance error returns, the S7DOS drivers (S7DOS / S7OpmDiag / S7EtherS7) are likely corrupted. Repair the ProTool/Step 7 installation from Control Panel > Add or Remove Programs, or run the Step 7 Install Driver routine to re-register the S7 communications services.
For deeper background on the CP5511 driver state, refer to the Siemens FAQ entries: FAQ 9853739, FAQ 12259435, and FAQ 19279714.
10. Cable and Connector Verification
A common confusion is the use of a plain RS-232 null-modem cable for what is expected to be MPI transfer. The OP170B has a single DB-9 port that is software-switchable between serial point-to-point (for OS/project transfer) and MPI. The cable itself, however, is not interchangeable:
- Serial point-to-point (OS update, ProSave backup): a 1:1 null-modem cable with full handshaking loopback is acceptable.
- MPI / Profibus DP (runtime and project transfer): a Profibus cable (purple, twisted pair, foil + braid shield) terminated with 6ES7 972 Profibus connectors is required. The connectors provide the bus terminator resistor and the Profibus signal conditioning. A plain RS-232 cable will not work for MPI even though the connector is the same DB-9 form factor.
If the OP170B sits at the end of the bus, leave the terminator resistor ON on that connector; remove it from any mid-bus connector. With only one OP and one PLC, both end connectors should be ON.
11. Transfer and Verification Procedure
- Power up the PLC and the OP170B. Wait for the PLC to reach run/stop-ready (STOP or RUN with no SF).
- On the OP170B, enable Channel 2 (MPI) and the Remote Control flag.
- On the PC, open PG/PC Interface and run Diagnostics. Confirm that the panel (address 1) and the CP 343-5 (or the CPU, if directly on MPI) are visible.
- Open the ProTool project, recompile, and select File > Download > Preferences > MPI.
- Click the Transfer icon. A second MPI channel should appear in the diagnostic window once the transfer starts.
- Wait for the progress bar to reach 100% and for the panel to reboot automatically.
- After reboot, the panel must show the start screen of the new project and the PLC status indicator on the bottom-right should switch from "no connection" to "connection established".
- Trigger at least one tag from the panel (for example a motor start) and confirm the value is read back in Step 7 with a VAT or a status word monitor.
12. Diagnostic and Troubleshooting Matrix
| Symptom | Check | Resolution |
|---|---|---|
| Diagnostic shows only PG/PC address 0 | OP not yet powered, or Channel 2 disabled | Enable Channel 2 and Remote Control; cycle panel power |
| Diagnostic shows 0, 2, 3, not 1 | OP address in panel set to something other than 1, or duplicate address on bus | Set OP MPI address to 1, confirm no other node uses 1 |
| Compile succeeds, transfer fails after 10-15 s | PG/PC address conflict, wrong bus role | Set PG/PC MPI to 0, set panel to "only master" only if no other master |
| Transfer dialog asks for routing | Peer selection points to a non-bus node (for example CPU behind a CP) | Repoint peer to CP 343-5; recompile |
| CP5511 not selectable | Stale driver / hidden device | Uninstall in Device Manager, reboot, reinsert |
| Intermittent transfer dropouts | Missing terminator, long stub, EMI | Check terminator at both ends, shorten stubs to < 1 m, separate from VFD cables |
| OS update OK, project transfer fails | Wrong cable for transfer type | Use Profibus cable with Profibus connector for MPI transfer |
| Compile error about symbol list | Symbol list bound to wrong network/peer | Re-choose communication peer/symbol list from the MPI network |
13. Field-Proven Caveats
- The OP170B MPI port is not electrically isolated from the panel's 24 V supply. A missing PE connection on the panel can shift the bus reference and cause intermittent bus dropouts. Bond PE before chasing software causes.
- ProTool V6.0 SP3 is the last release that supports the OP170B natively. WinCC flexible 2004 SP1 and later also support the OP170B via the OP170B Migration option; migrating the project to WinCC flexible changes the file format irreversibly.
- When the PLC is a CPU 315-2DP and the operator station is a CP 343-5 connected to a Profibus subnet, the OP and the CPU are on different logical networks. The OP must therefore speak to the CP 343-5, and the CP 343-5 must be configured in Step 7 to forward S7 connections to the CPU. A common commissioning gap is configuring the CP as a DP slave without enabling S7 routing.
- Setting PG/PC is the only master on the bus while the CPU is also master produces token collisions. Enable that option only when the panel/PG is the sole bus master, which is uncommon in a running plant.
- Some PCMCIA slots do not supply enough current for the CP 5511. Use a powered PCMCIA adapter or a PC Adapter USB (6ES7 972-0CB20-0XA0) instead.
14. FAQ
Why does the OP170B show "This configuration was edited in an earlier version of ProTool"?
The project's version stamp is older than the installed ProTool. Confirm the prompt to forward-save, but always keep an offline copy of the original .pdb because the forward save cannot be undone.
What causes "Project data being synchronized (Open) cannot be routed to the required communication peer"?
ProTool is trying to reach a peer that is not on the bus the panel is connected to. Point the peer at the CP 343-5 (or the bus-visible CPU/CP) and select the correct MPI network under Choose a communication peer/symbol list. Save, recompile, and retransfer.
The PG/PC diagnostic lists addresses 0, 2, 3 but not 1 (the OP). What is wrong?
Either Channel 2 is disabled, Remote Control is off, or the OP is not on the bus. Open Control Panel > Transfer on the panel, enable Channel 2 and Remote Control, and confirm the OP's MPI address is set to 1 with a baudrate of 187.5 kbps and a highest station address of 31.
CP5511 driver install fails with "maximum number of interfaces already installed". How do I fix it?
Uninstall all instances of the CP 5511 in Windows Device Manager (including hidden devices), reboot, then reinsert the card so Windows performs a fresh Plug&Play install. If the error persists, repair the Step 7 / ProTool installation to re-register the S7DOS drivers.
Can I use the same RS-232 null-modem cable for both OS update and MPI transfer?
No. OS update and ProSave backup use a serial point-to-point link, which works with a null-modem cable. MPI/DP transfer requires a Profibus cable with Profibus connectors (for example 6ES7 972-0BA12-0XA0) because the signal levels and termination differ.