Problem Overview
When WinCC Flexible 2008 Runtime (or a SIMATIC Panel configured in WinCC Flexible) reports "no response" against a Siemens SIMATIC S7-200 PLC while the same PLC responds normally to STEP 7 Micro/WIN, the fault almost always lives at the boundary between the HMI runtime, the PC/PPI cable, and the PG/PC interface (access point) layer in Windows — not in the S7-200 user program. Micro/WIN uses its own dedicated PPI/USS/Freeport driver stack and will communicate even when the runtime channel is broken.
This article enumerates the supported connection paths from WinCC Flexible Runtime to the S7-200, then walks through the cable DIP-switch settings, access point configuration, baud-rate matching, and laptop hardware adapters required to eliminate the no-response fault. Field-proven settings and Siemens Entry ID references are included so the procedure is reproducible on the bench.
The canonical Siemens FAQ for this scenario is Siemens Entry ID 16532946, "What should you watch out for when setting up a connection between S7-200 and SIMATIC Panels or WinCC flexible PC Runtime and what are the options?" The same Entry ID also covers the CP 243-1 Ethernet path and the EM 277 PROFIBUS path. Use it as the primary reference when escalating to Siemens support.
Root Cause Analysis
Five independent layers must agree before WinCC Flexible Runtime can exchange data with an S7-200. A single mismatch produces the silent "no response" symptom (no red LED on the PLC PPI port, no diagnostic event in WinCC).
- Physical layer — cable type, gender, DIP-switch position, USB/serial enumeration, RS-232 to RS-485 conversion.
- Windows device layer — USB-PPI enumerated as a virtual COM port or as a Siemens USB device; serial-PPI mapped to a real COM port.
-
PG/PC interface layer — the Set PG/PC Interface control panel must assign the access point
S7ONLINEto the correct driver. - WinCC Flexible connection layer — protocol selection (PPI / MPI / PROFIBUS / Ethernet), PLC address, and slot/rack parameters must match the PLC.
- CPU parameter layer — the S7-200 system block must allow PPI communication and must use a baud rate the cable supports.
Supported Connection Paths
WinCC Flexible Runtime (and the WinCC Flexible ES that targets a SIMATIC Panel) supports the following physical paths to an S7-200. Confirm one path matches the hardware on hand before any software configuration.
| Path | Cable / Module | Order Number | Notes |
|---|---|---|---|
| PPI (point-to-point) | PC/PPI cable, RS-232 side | 6ES7901-3BF00-0XA0 | 6-position DIP switch; USB serial converter often required for laptops |
| PPI (USB variant) | PC/PPI cable, USB side | 6ES7901-3CB30-0XA0 | Requires Siemens USB driver; not all WinCC Flexible builds enumerate it |
| MPI / PPI multi-master | CP 5611 PCI card | 6GK1561-1AA01 | Up to 187.5 kbps on PPI bus |
| MPI / PROFIBUS | CP 5612 PCI card | 6GK1561-2AA00 | DP-Master capable; needed for PROFIBUS path |
| MPI / PROFIBUS | CP 5512 PCMCIA / ExpressCard | 6GK1551-2AA00 | Laptop solution when CP 5611/5612 is unavailable |
| Ethernet (TCP/IP) | CP 243-1 Ethernet module on S7-200 | 6GK7243-1EX01-0XE0 | PLC becomes a TCP server; WinCC Flexible uses ISO-on-TCP |
| Ethernet (IT) | CP 243-1 IT | 6GK7243-1GX00-0XE0 | Adds e-mail, HTTP, FTP on top of the CP 243-1 base |
| PROFIBUS DP | EM 277 module on S7-200 | 6ES7277-0AA20-0YA0 | WinCC Flexible acts as DP master via CP 5611/5612 |
PC/PPI Cable DIP Switch Configuration
The RS-232 PC/PPI cable (6ES7901-3BF00-0XA0) is a six-position DIP switch that controls baud rate, master/slave behavior, echo mode, and the on-board RS-232/RS-485 converter. The factory default (all OFF) often mismatches the WinCC Flexible configuration.
| DIP Switch | ON position | OFF position | Recommended for WinCC Flexible + S7-200 |
|---|---|---|---|
| 1 — Mode select | PPI / Freeport | PPI only | OFF (PPI only) for clean WinCC link |
| 2 — Echo | Local / Remote echo | No echo | OFF (no echo) unless troubleshooting with terminal |
| 3 — Baud bit 1 | — | — | Per baud rate table below |
| 4 — Baud bit 2 | — | — | Per baud rate table below |
| 5 — Baud bit 3 | — | — | Per baud rate table below |
| 6 — Converter | PPI / RS-232 converter | RS-485 / RS-232 converter | OFF (RS-485 converter) — required for S7-200 PPI port |
Baud rate DIP map (switches 3-4-5). Set all three switches the same way as shown:
| DIP 3 | DIP 4 | DIP 5 | Baud rate (bps) |
|---|---|---|---|
| OFF | OFF | OFF | 1 200 (PC/PPI default) |
| ON | OFF | OFF | 2 400 |
| OFF | ON | OFF | 4 800 |
| ON | ON | OFF | 9 600 (S7-200 default) |
| OFF | OFF | ON | 19 200 |
| ON | OFF | ON | 38 400 |
| OFF | ON | ON | 57 600 |
| ON | ON | ON | 115 200 |
WinCC Flexible Connection Configuration
In the WinCC Flexible project, open Project → Communication → Connections and create a new connection with these parameters:
| Field | PPI path | MPI path | Ethernet path |
|---|---|---|---|
| Communication driver | SIMATIC S7-200 PPI | SIMATIC S7-200 MPI | SIMATIC S7-200 Ethernet (CP 243-1) |
| Online / Offline | Online | Online | Online |
| PLC address (HMI side) | 1 (default HMI station) | 1 | — |
| PLC address (CPU side) | 2 (S7-200 default) | 2 | — |
| Slot / Rack | 0 / 0 | 0 / 0 | 0 / 0 |
| Network profile | PPI | MPI | Ethernet |
| TSAP / Port | — | — | 10.00 (local) / 10.00 (remote) — CP 243-1 wizard default |
The CPU address must match the address assigned in Micro/WIN (Tools → System Block → Communication Ports). If Micro/WIN was used as the programming tool, the CPU address is typically 2 and the baud rate is 9 600 bps.
PG/PC Interface and Access Point Setup
This is the layer most engineers miss. WinCC Flexible does not talk to the COM port directly — it talks to the access point S7ONLINE, which in turn is bound to a specific driver. Misbinding S7ONLINE is a silent fault: WinCC starts, but no frames reach the bus.
- Open Start → Control Panel → Set PG/PC Interface (32-bit) or Start → Siemens Automation → Set PG/PC Interface (after installation of SIMATIC software).
- In the Access Point of the Application dropdown, select
S7ONLINE. - In the Interface Parameter Assignment Used list, choose the appropriate driver:
- For RS-232 PC/PPI cable:
PC/PPI cable (PPI) - For USB-PPI cable:
PC USB cable (PPI) - For CP 5611/CP 5612/CP 5512 on PPI:
CP xxxx (PPI) - For PROFIBUS DP:
CP xxxx (PROFIBUS) - For Ethernet (CP 243-1):
TCP/IP → CP xxxxorTCP/IP → Local Area Connection
- For RS-232 PC/PPI cable:
- Click Properties and confirm the baud rate matches the cable DIP switches and the PLC system block.
- Click OK, then OK again to commit.
Addressing and Baud Rate Matching
The three baud rates in the chain must match exactly:
- Cable DIP switches (PC/PPI cable)
- S7-200 system block (Micro/WIN → System Block → Communication Port 0)
- PG/PC interface driver properties
WinCC Flexible does not let you enter the baud rate directly in the connection dialog — it inherits the baud rate from the PG/PC interface. If the cable and the PLC are both set to 9 600 bps but the PG/PC interface was left at 19 200 bps, the S7-200 ignores the request silently.
Standard baud rates supported on the S7-200 PPI port: 1 200, 2 400, 4 800, 9 600, 19 200, 38 400, 57 600, 115 200 bps. The PC/PPI cable supports all eight. CP 5611/CP 5612/CP 5512 cap at 187 500 bps when configured as PPI master.
Laptops without Serial Port: Adapters and CP Cards
Modern laptops drop the DB-9 RS-232 port. Three remedies, in order of preference:
- USB-PPI cable (6ES7901-3CB30-0XA0) — Siemens-validated. Install the Siemens USB driver that ships with the cable. Avoid generic USB-to-RS232 converters behind a PC/PPI cable: the PC/PPI cable draws +5 V from the serial handshake lines for the RS-485 transceiver, and a generic USB-serial adapter often cannot source the required current, producing intermittent "no response" faults.
- CP 5512 PCMCIA / ExpressCard (6GK1551-2AA00) — PROFIBUS/MPI card with a 9-pin D-sub. Works at full PPI baud rate and lets the cable and CP coexist on the bus.
- CP 5611 PCI Express (6GK1561-1AA01) — desktop replacement when an ExpressCard slot is unavailable.
A generic USB-to-RS232 adapter (for example FTDI FT232) will enumerate a COM port but typically cannot drive the PC/PPI cable RS-485 converter. The symptom is: Micro/WIN fails to connect first, which is the opposite of what the original poster reports.
DB9 Gender Changer and Null Modem Considerations
The PC/PPI cable is terminated in a female DB-9 on the PC side (it plugs into the male DB-9 of the PC). If the laptop serial port — or a USB-serial adapter — also exposes a male DB-9, a gender changer (M-M) is required. A null modem is not required for the PC/PPI cable because the cable already implements the required cross-over.
Pin reference (PC/PPI cable, DB-9 female to PC):
| Pin | Signal | Direction | Required |
|---|---|---|---|
| 2 | RD (Receive Data) | From cable | Yes |
| 3 | TD (Transmit Data) | To cable | Yes |
| 4 | DTR | To cable | Yes (powers RS-485 driver) |
| 5 | GND | — | Yes |
| 6 | DSR | From cable | Optional |
| 7 | RTS | To cable | Yes (powers RS-485 driver) |
| 8 | CTS | From cable | Optional |
| 1, 9 | DCD, RI | — | Not used |
Ethernet Alternative via CP 243-1
If the laptop does not have a serial port and a CP card is not available, the cleanest solution is to add a CP 243-1 Ethernet module to the S7-200 and use the Ethernet path. This eliminates the RS-232 / RS-485 boundary entirely.
- In Micro/WIN, run the Ethernet Wizard and configure CP 243-1 with a static IP address (for example
192.168.0.10), subnet mask255.255.255.0, and TSAP pair10.00 → 10.00. - Place the CP 243-1 configuration in the S7-200 project data block area (the wizard generates this automatically).
- In WinCC Flexible, add a new connection and select the driver SIMATIC S7-200 Ethernet (CP 243-1).
- Enter the CP 243-1 IP address, the remote TSAP (default
10.00), and confirm the rack/slot pair0 / 0. - Bind
S7ONLINEto the local Ethernet adapter (TCP/IP → Local Area Connection) in Set PG/PC Interface. - Download the WinCC Flexible project to the runtime, start Runtime, and verify a tag read.
The CP 243-1 wizard default TSAP pair is documented in the S7-200 system manual on the Siemens Industry Online Support portal.
PROFIBUS DP Alternative
For sites that already have a PROFIBUS backbone, an EM 277 PROFIBUS DP slave module on the S7-200 plus a CP 5611 / CP 5612 / CP 5512 master on the WinCC Flexible PC keeps the cable plant intact and avoids any RS-232 boundary.
- Mount the EM 277 on the S7-200 bus connector and assign it a PROFIBUS address (1–125, default 2).
- Configure the EM 277 input/output mapping in the S7-200 symbol table.
- In WinCC Flexible, create a PROFIBUS DP connection and select the SIMATIC S7-200 DP driver.
- Bind
S7ONLINEtoCP xxxx (PROFIBUS)in Set PG/PC Interface. - Configure the bus parameters (baud rate up to 12 Mbps) and download.
Driver Installation and Verification
WinCC Flexible 2008 SP5 and earlier rely on the Windows-side drivers shipped with SIMATIC STEP 7 and SIMATIC NET. Verify in Device Manager before assuming the cable is wired correctly:
- Open Device Manager → Ports (COM & LPT) for RS-232 PC/PPI and USB-PPI cables.
- Open Device Manager → Siemens AG → CP 5611 / CP 5612 / CP 5512 for PC cards. A yellow exclamation mark indicates a missing or unsigned driver.
- Open Control Panel → Set PG/PC Interface and confirm the access point
S7ONLINEis mapped to a healthy driver. - Run Start → Programs → Siemens Automation → Communication Settings → Diagnostics (or PC-internal CP diagnostics) to confirm the cable or CP can enter the bus.
WinCC Flexible Runtime Licensing and Components
WinCC Flexible Runtime installs three components on the engineering PC:
- WinCC flexible Runtime — the HMI runtime engine.
- WinCC flexible ES — the configuration software (already present in development).
- SIMATIC S7-200 drivers — PPI, MPI, Ethernet (CP 243-1), and DP. These are selected at installation time under Components → Communication → S7-200.
If the S7-200 PPI/MPI/DP driver component is unchecked during install, the runtime can be started and a project can be loaded but no S7-200 driver appears in the connection dialog. Reinstall WinCC Flexible with the S7-200 communication option enabled.
WinCC Flexible 2008 SP5 is the final service pack for the WinCC Flexible 2008 line. WinCC Flexible 2008 SP1 through SP5 all support the S7-200 drivers. Migration to TIA Portal WinCC (Comfort / Advanced) drops S7-200 support from TIA V13 onward — the S7-200 must be replaced with an S7-1200 or accessed through legacy components.
Step-by-Step Commissioning Procedure
- Verify the PLC responds from Micro/WIN. If Micro/WIN cannot connect, fix the PLC first.
- Read the PLC system block in Micro/WIN: Tools → System Block → Communication Port 0 → confirm baud rate (default 9 600), PPI address (default 2), and that PPI mode is enabled.
- Set the PC/PPI cable DIP switches to match the PLC baud rate (DIP 3-4-5 to ON-ON-OFF for 9 600 bps) and switch 6 to OFF (RS-485 converter).
-
Open Set PG/PC Interface and bind
S7ONLINEtoPC/PPI cable (PPI)at the matching baud rate. -
Open the WinCC Flexible project → Communication → Connections → add a connection using driver
SIMATIC S7-200 PPI, HMI address 1, CPU address 2, slot 0, rack 0. - Compile and download the project to the WinCC Flexible Runtime PC.
- Start Runtime. The HMI tag list should resolve. If "no response" persists, advance to the troubleshooting matrix.
Verification Checklist
| # | Check | Pass criteria |
|---|---|---|
| 1 | S7-200 SF / BF LEDs | Both off at idle |
| 2 | PLC PPI LED (Port 0) | Flickers during request |
| 3 | Device Manager → COM port | PC/PPI cable enumerated without yellow bang |
| 4 | Set PG/PC Interface → S7ONLINE | Bound to PC/PPI cable (PPI)
|
| 5 | Baud rate triangle (cable / PLC / PG-PC) | All three values identical |
| 6 | CPU address uniqueness on bus | Each station 1–31 only once |
| 7 | WinCC Flexible connection dialog | Driver SIMATIC S7-200 PPI selectable |
| 8 | WinCC Flexible Runtime start log | Connection entry shows OK, not Error |
| 9 | Tag read in Runtime | Placed tag displays expected value |
| 10 | CP 243-1 path (if used) — ping | Ping to CP 243-1 IP succeeds |
Troubleshooting Matrix
| Symptom | Likely cause | Fix |
|---|---|---|
| No response, no error message, Micro/WIN works | PG/PC interface not bound to S7ONLINE | Re-bind access point S7ONLINE → PC/PPI cable (PPI) |
| No response, Micro/WIN does not work either | Baud rate mismatch between cable DIP and PLC system block | Set cable DIP 3-5 to match PLC baud rate (default 9 600 bps) |
| COM port missing in Device Manager | Generic Windows HID driver loaded instead of Siemens USB driver | Uninstall HID, force-install Siemens USB-PPI driver |
| CP 5611 / 5612 / 5512 shows yellow bang | SIMATIC NET PC software missing or unsigned driver | Install SIMATIC NET PC and reboot |
| WinCC Flexible connection dialog greyed out for S7-200 PPI | S7-200 communication component unchecked at install | Modify WinCC Flexible installation, enable S7-200 drivers |
| No frames on PPI LED | DTR/RTS not driven by USB-serial adapter | Replace generic USB-serial with Siemens USB-PPI cable or CP card |
| Intermittent communication, restart fixes | DIP switch 6 in wrong position (RS-232 converter mode) | Set DIP 6 OFF for RS-485 conversion to S7-200 |
| DB-9 male-to-male physical fit problem | Both cable and laptop expose male DB-9 | Use a gender changer (M-M); do not add a null modem |
| Runtime starts but tags stay "###" | CPU address wrong (HMI = 1, CPU = 2 default); or duplicate address on bus | Reassign CPU address in System Block; verify bus uniqueness |
| Ethernet path: connection refused | CP 243-1 wizard not downloaded to S7-200; TSAP mismatch | Re-run Ethernet Wizard, download configuration, match TSAP pair 10.00/10.00 |
| USB-PPI cable not detected on Windows 10 / 11 | Driver signature enforcement rejects legacy unsigned driver | Boot with driver-signature enforcement disabled, or install signed Siemens replacement |
| Set PG/PC Interface control panel missing | SIMATIC STEP 7 / SIMATIC NET not installed | Install SIMATIC NET PC software package |
Field-Proven Caveats
- USB-PPI enumeration on Windows 10 / 11: The legacy USB-PPI driver is unsigned. Disable driver signature enforcement or use a signed wrapper when commissioning on a modern OS.
-
Multiple access points: STEP 7 and WinCC Flexible both default to
S7ONLINE, but Micro/WIN usesMicro/WIN. Do not point Micro/WIN atS7ONLINEor you will lose STEP 7 connectivity. - Siemens Entry ID 16532946 is the canonical Siemens FAQ for WinCC Flexible + S7-200 paths. Always quote this entry ID when escalating to Siemens support.
- End-of-life reminder: S7-200 and WinCC Flexible 2008 are both legacy products. New deployments should target S7-1200 / S7-1500 with TIA Portal WinCC (Comfort / Advanced). The CP 243-1 module, however, is still supported on legacy sites and remains the cleanest Ethernet upgrade.
- MPI cable substitution: A standard MPI cable (for example 6ES7901-0BF00-0AA0) can be used to attach a CP 5611/CP 5612/CP 5512 to the S7-200 PPI port. WinCC Flexible will treat the bus as PPI regardless of the cable type, because the protocol is defined by the access point binding, not by the cable.
- Power-on order: Always power the S7-200 CPU before attaching the PC/PPI cable. Hot-plugging the cable to a powered CPU can corrupt the in-flight PPI frame and produce a transient no-response event in WinCC Flexible.
FAQ
Does WinCC Flexible Runtime require a separate driver installation for the S7-200 PPI path?
Yes. The SIMATIC S7-200 communication option must be selected during WinCC Flexible installation. If unchecked, the S7-200 PPI / MPI / Ethernet / DP drivers do not appear in the connection dialog and Runtime will not communicate with the S7-200. Re-run the WinCC Flexible installer, choose Modify, and enable Communication → S7-200.
Can a USB-PPI cable be used instead of the RS-232 PC/PPI cable?
Yes, order number 6ES7901-3CB30-0XA0. The Siemens USB-PPI driver must be installed; a generic USB-to-serial adapter behind an RS-232 PC/PPI cable usually fails because the PC/PPI cable draws +5 V from the DTR / RTS handshake lines that generic adapters do not drive.
What is the correct access point for the S7-200 PPI driver?
The access point is S7ONLINE. In Control Panel → Set PG/PC Interface, map S7ONLINE to PC/PPI cable (PPI) for the RS-232 cable, PC USB cable (PPI) for the USB cable, or CP xxxx (PPI) for CP 5611/5612/5512. The baud rate in the driver properties must match the PC/PPI cable DIP switches and the S7-200 system block (default 9 600 bps).
Why does Micro/WIN communicate but WinCC Flexible shows "no response"?
Micro/WIN uses its own PPI driver bound to the access point Micro/WIN, not S7ONLINE. WinCC Flexible uses the drivers installed under S7ONLINE. A successful Micro/WIN session proves the S7-200 is alive on the bus; it does not prove that S7ONLINE is bound to the correct driver. Re-bind S7ONLINE to the PC/PPI cable (PPI) at the matching baud rate to resolve the silent no-response fault.
Can the S7-200 be connected over Ethernet instead of PPI?
Yes, by mounting a CP 243-1 Ethernet module (6GK7243-1EX01-0XE0) on the S7-200. Configure the module with the Micro/WIN Ethernet Wizard, assign a static IP, default TSAP pair 10.00 / 10.00, and select the SIMATIC S7-200 Ethernet (CP 243-1) driver in WinCC Flexible. This path eliminates the RS-232 / RS-485 boundary and is recommended for laptops without serial ports.
Do I need a CP 5611 / CP 5612 / CP 5512 to use WinCC Flexible, or is the PC/PPI cable enough?
The PC/PPI cable is sufficient for a single PC / single S7-200 PPI link. CP 5611, CP 5612, or CP 5512 are required if you want a true RS-485 multi-drop PPI/MPI bus, a PROFIBUS DP master, or a higher baud rate (above 115 200 bps up to 187 500 bps) on the PPI bus. For most bench commissioning with one S7-200, the PC/PPI cable is the lowest-friction path.