Resolving S7-PLCSIM Download Error 33:17090 After Post-Installation in PCS 7

In SIMATIC PCS 7 V7.0 SP1, encountering the error "Download to module (33:17090) A connection between your PC/PG and the automation device cannot be established" after subsequently installing S7-PLCSIM V5.4 occurs because the post-facto installation failed to register virtual communication driver hooks or because an Access Point mismatch exists in "Set PG/PC Interface". Installing S7-PLCSIM on top of an existing PCS 7 installation often leaves the virtual driver (s7wsviax.dll) unbound from the STEP 7 Device Management registry. Resolving this issue requires configuring the PG/PC interface access point S7ONLINE to match the exact simulated interface (PLCSIM.MPI.1, PLCSIM.PROFIBUS.1, or PLCSIM.TCPIP.1), executing driver re-registration via s7wneta.exe, and ensuring version compatibility via the Siemens Kompatool.

Root Causes of S7-PLCSIM Error 33:17090

Engineering teams frequently install S7-PLCSIM onto an existing SIMATIC PCS 7 Engineering Station to perform offline logic testing, alarm validation, and virtual commissioning. In PCS 7 V7.0 SP1, engineers installing S7-PLCSIM V5.4 frequently report that although the simulated CPU starts and displays healthy RUN status in the PLCSIM window, any download attempt from SIMATIC Manager or CFC aborts immediately with:

Download to module (33:17090): A connection between your PC/PG and the automation device cannot be established.

This fault occurs regardless of whether MPI, PROFIBUS, or TCP/IP is selected in PLCSIM, and even affects standard Siemens example projects. The underlying failure is caused by an unlinked virtual communication channel in the Windows communications subsystem: during post-installation, the PLCSIM virtual device driver fails to insert its communication multiplexer into the existing SIMATIC NET communication registry.

Set PG/PC Interface Access Point Alignment

To establish communication with S7-PLCSIM, the active access point must align perfectly with the selected simulation protocol:

S7-PLCSIM Node SettingSTEP 7 Set PG/PC Interface ParameterTarget HW Config SubnetSupported PCS 7 Download TypesMPI (Default Address 2)PLCSIM.MPI.1CPU Onboard MPI PortBasic STEP 7 blocks; limited CFC downloadsPROFIBUS (Address 2 or configured DP)PLCSIM.PROFIBUS.1CPU Onboard DP PortFull CFC Program; hardware configurationTCP/IP (RFC 1006 / IP Subnet)PLCSIM.TCPIP.1CP 443-1 / CPU PN PortFull PCS 7 Multiproject; AS-OS simulationISO Industrial EthernetPLCSIM.ISO.1CP 443-1 Industrial EthernetSupported in specific PLCSIM releases with CP1613

If PLCSIM is set to listen on MPI while the PG/PC interface is configured for PLCSIM.TCPIP.1 (or remains pointing to a physical CP card like CP1613(ISO)), the download engine attempts to reach non-existent hardware, generating error 33:17090.

Post-Installation Driver Re-Registration Procedure

If access points match but error 33:17090 persists, the virtual communication driver must be re-registered:

Close All SIMATIC Applications: Close SIMATIC Manager, CFC, HW Config, and S7-PLCSIM. Open Task Manager and verify that s7tgtopx.exe, s7wsviap.exe, and ccapp.exe are terminated.
Re-Register Network Drivers via Command Line:
- Open Windows Command Prompt as Administrator.
- Navigate to the Siemens Common directory:
cmd cd "C:\Program Files\Common Files\Siemens\S7WNIX\BIN"
(or C:\Program Files (x86)\Common Files\Siemens\S7WNIX\BIN).
- Execute the network driver registration utility:
cmd s7wneta.exe /r
- This command purges stale virtual communication bindings, rebuilds the SIMATIC Device Management database, and binds s7wsviax.dll to the PG/PC interface table.
Re-Apply Service Packs:
- Ensure that the S7-PLCSIM version is fully compatible with PCS 7 V7.0 SP1. According to the Siemens Compatibility Tool (Kompatool), PCS 7 V7.0 SP1 requires S7-PLCSIM V5.4 SP1 or higher. If S7-PLCSIM V5.4 base release was installed, apply S7-PLCSIM V5.4 SP3 or SP5.

CFC Simulation Download Configuration Rules

When downloading a PCS 7 CFC program to S7-PLCSIM:
1. Launch S7-PLCSIM before initiating the download in SIMATIC Manager.
2. In the PLCSIM menu, select the interface: Execute -> Open... or toggle the interface selector in the bottom status bar to PLCSIM(MPI) or PLCSIM(PROFIBUS).
3. In SIMATIC Manager, open Options -> Set PG/PC Interface...; verify that S7ONLINE (STEP 7) is set to the identical PLCSIM parameter.
4. In CFC, click Chart -> Compile -> As Program; then click PLC -> Download. Select Entire program for the initial load into PLCSIM.

Verification

To verify that PLCSIM download capability is fully restored:
1. In S7-PLCSIM, switch the virtual CPU to STOP mode.
2. In SIMATIC Manager, select the S7 Program and click PLC -> Download.
3. Confirm that the download progress bar advances without error 33:17090 and that system blocks transfer cleanly.
4. Switch S7-PLCSIM to RUN-P mode; open a CFC chart and turn on online watch mode; verify that live block values update dynamically.

Limitations and Operational Precautions

S7-PLCSIM V5.4 does not support all hardware features of real S7-400 controllers. Specifically, hardware interrupts (OB40), diagnostic interrupts from real ASIC fieldbus cards (OB82), and high-availability redundant switchover (H-sync) cannot be fully emulated in standard PLCSIM. S7-PLCSIM must not remain active on an Engineering Station that is actively downloading to a physical controller on the Plant Bus.

Engineer FAQ

What does error 33:17090 mean in STEP 7?

Error 33:17090 indicates that STEP 7 cannot establish a logical connection to the target device through the currently selected communication driver and node address.

Why does post-installing PLCSIM break the driver bindings?

Installing PLCSIM after the complete PCS 7 suite can overwrite newer communication DLLs with older versions, or fail to register virtual adapter handles in the Windows registry.

Can PLCSIM simulate an S7-400H redundant CPU pair simultaneously?

Standard S7-PLCSIM V5.4 can only simulate one CPU at a time. Simulating redundant S7-400H pairs requires S7-PLCSIM Advanced or SIMIT Virtual Controller.