What is S7 Comm Plus?
S7 Comm Plus is the secured version of the Siemens S7 communication protocol, developed for use with modern Siemens PLCs such as the S7-1200 and S7-1500. It provides encryption, authentication, and integrity checking for data traffic between controllers, SCADA systems, Engineering Stations, and other clients.
Unlike the classic S7 protocol (used with S7-300/400), S7 Comm Plus has been designed with modern Cybersecurity requirements in mind.
🧠 How does S7 Comm Plus work?
- Encryption via TLS
- Traffic between devices is encrypted using Transport Layer Security (TLS)
- Prevents eavesdropping and manipulation of data traffic
- Client authentication with certificates
- Only authorised systems with valid digital certificates are allowed to connect
- Part of Certificate Management within Siemens TIA Portal
- Protocol-specific security
- Ability to restrict commands (e.g. read-only)
- Integrity and origin of data is verified
S7 Comm Plus makes it possible to communicate securely over uncontrolled networks, for instance during Remote Access or integration with IT systems.
🏭 Application in industrial networks
- Secure communication between S7-1500 PLCs and SCADA systems (such as WinCC)
- Secured engineering sessions from Engineering Station via TIA Portal
- Integration with OPC UA servers and Historians without protocol conversion
- Remote access to PLCs via VPN or Industrial Firewall with DPI
Applicable in:
- Critical infrastructure (energy, water, transport)
- High-end production lines with elevated cyber risks
- OT networks with Zero Trust architecture
🔍 S7 Classic vs. S7 Comm Plus
| Characteristic | S7 (classic) | S7 Comm Plus |
|---|---|---|
| Security | No encryption or authentication | TLS encryption, certificate-based access |
| Port used | TCP 102 | TCP 443 or another port via TLS |
| Devices | S7-300, S7-400 | S7-1200, S7-1500 |
| Configuration | STEP 7 (legacy) | TIA Portal (from v15) |
S7 Comm Plus is not backward compatible with classic S7 PLCs.
🔐 Security aspects
- Certificate management is required (Certificate Management)
- Integrate with Firewall and Access Control to restrict traffic to authorised clients
- Monitor TLS handshakes and certificate expiry via SIEM or Monitoring
- Combine with anomaly detection to detect misuse of permitted communication
- Regular firmware and certificate updates are essential for security
Well-implemented S7 Comm Plus configurations significantly increase the resilience of OT networks.
📌 In summary
S7 Comm Plus provides encrypted, authenticated communication for Siemens S7-1200/1500 PLCs. It is an important component of a secure and future-proof OT network and replaces the vulnerable classic S7 protocol.