Networking 12 S7-1200 PLCs with PROFINET and TIA Portal

Overview

Connecting twelve SIMATIC S7-1200 controllers over PROFINET and supervising them from a single engineering station running TIA Portal is a standard machine-builder topology. The architecture consists of three layers:

1. Controller layer — twelve S7-1200 CPUs (e.g. CPU 1214C, CPU 1215C, or CPU 1217C), each with a built-in PROFINET interface on port X1 P1 / X1 P2.
2. Network layer — industrial Ethernet switches that interconnect the CPUs and provide uplink to the engineering station. Suitable devices include the unmanaged CSM 1277 (4 ports), the managed SCALANCE XB-208 (8 ports), and the managed SCALANCE XR-320 (20 ports).
3. Supervisory layer — either a SIMATIC HMI Panel or a PC running WinCC Advanced PC Runtime, both programmed inside TIA Portal.

PROFINET is the only industrial Ethernet protocol the S7-1200 line natively supports. Conformance Class A is sufficient for cyclic I/O and acyclic diagnostics; conformance Class B (LLDP, SNMP, port statistics) is recommended when a managed switch such as SCALANCE is used. PROFINET cabling per IEC 61784-2 and IEC 61918 is required when installing in cabinets with EMC exposure; field installation uses Cat 5e/Cat 6 SF/UTP or FC TP cables (6XV1 8xx series).

Prerequisites

Network Architecture Options

Three topologies are realistic for twelve S7-1200 nodes. Choose by budget, panel-vs-PC preference, and the redundancy requirements of the line.

Option A — Star with CSM 1277 unmanaged switches

Each CSM 1277 provides 4 RJ45 ports. With 12 PLCs the minimum is six switches daisy-chained, or five switches with the engineering PC connected to the sixth port of the central switch.

• Article number: 6GK7277-1AA10-0AA0 (CSM 1277, 4×RJ45 10/100 Mbit/s, unmanaged)
• Manual: SCALANCE / CSM 1277 operating instructions
• Total port count for 12 PLCs + 1 PC = 13 ports » 5×CSM 1277 if the PC is patched into any switch.
• Pros: cheapest, smallest footprint (45 mm wide), no configuration.
• Cons: no diagnostics, no SNMP, no port mirroring — troubleshooting must be done at the PLC.

Option B — SCALANCE XB-208 managed switch

Two SCALANCE XB-208 switches (8 ports each) give 16 ports. Twelve PLCs occupy all twelve ports on switch A; switch B is reserved for the engineering station, an HMI panel, and the uplink to the office network.

• Article number: 6GK5208-0BA10-2AA3 (SCALANCE XB-208, 8×RJ45 10/100 Mbit/s, managed, PROFINET conformance class B)
• Manual: SCALANCE XB-208 operating instructions
• Pros: SNMP, web management, port statistics, LLDP topology discovery, optional C-PLUG memory card.
• Cons: higher unit cost; requires initial IP assignment for management.

Option C — SCALANCE XR-320 managed rack-mount

One SCALANCE XR-320 supplies 20 RJ45 ports, leaving 8 spare ports for spare PLCs, an HMI, an engineering PC, and an uplink. This is the cleanest architecture for new installations.

• Article number: 6GK5320-0BA01-2AA3 (SCALANCE XR-320, 20×RJ45, managed, 19" rack)
• Manual: SCALANCE XR-320 operating instructions
• Pros: 20 ports in one device, full Layer-2 management, optional redundancy (MRP, STP/RSTP), redundant power input 24 V DC.
• Cons: highest unit cost, 19" rack footprint.

Comparison matrix

PC Runtime vs Panel HMI

The S7-1200 line supports both SIMATIC Comfort Panels and external PC-based visualization. When the requirement is to monitor and control twelve CPUs from a single workstation without a physical panel, the standard solution is WinCC Advanced PC Runtime (originally marketed as WinCC V11 Advanced; current name in TIA Portal V17/V18/V19 is "WinCC Advanced" with the "PC Runtime" option).

WinCC Basic does not include PC Runtime. WinCC Comfort and WinCC Advanced do. WinCC Professional additionally supports WinCC Professional RT for server-class projects with redundancy.

WinCC Advanced Licensing

WinCC Advanced Runtime for PC is licensed by PowerTags. A PowerTag is one external process variable (HMI tag). Internal tags are free.

The base WinCC Advanced engineering software for TIA Portal is MLFB 6AV2102-0AA01-0AA5 (or current equivalent). If migrating from an existing WinCC flexible 2008 SP5 license, an upgrade license can be purchased instead of a full new license.

For 12 PLCs with 50–100 tags each, plan for at least 2048 PowerTags. The upgrade path is to start a project, count actual PowerTags via Project → Runtime → Licensing in TIA Portal, then purchase the matching license.

TIA Portal Configuration Step-by-Step

1. Create the project. Launch TIA Portal V18 (or current). Create new project → SIMATIC S7-1200 station. Add the twelve S7-1200 CPUs by drag-and-drop from the hardware catalog. Match each order number exactly (e.g. 6ES7214-1AG40-0XB0 for CPU 1214C DC/DC/DC).
2. Configure PROFINET interface. For each CPU open Device view → PROFINET interface → Ethernet addresses. Assign a unique IP, e.g. 192.168.0.11…192.168.0.22 with subnet mask 255.255.255.0. Enable "Use IP router" only if a gateway is present.
3. Assign PROFINET device names. In Devices & Networks right-click each CPU → Assign PROFINET device name. Use names plc-01…plc-12. Verify with the "Accessible nodes" function (Online → Accessible nodes) that all twelve names appear.
4. Configure the switch. For SCALANCE switches drag the device into the topology, set the management IP, enable LLDP for topology detection, and confirm the PROFINET device name. For CSM 1277 unmanaged switches no configuration is needed.
5. Add the HMI device. Insert SIMATIC HMI → PC station → WinCC Runtime Advanced. Under Connections add twelve HMI connections — one per CPU — with the protocol set to PROFINET and the partner matching the corresponding PLC IP.
6. Define HMI tags. Each connection can address the entire DB of the partner CPU. Use HMI tags → Add new with a meaningful naming scheme, e.g. PLC01_Motor1_Speed. Enable Acquisition mode: Cyclic continuous with a 1 s update rate.
7. Build the screens. Create a master overview screen with twelve buttons or area indicators, one per PLC. Use Screen navigation to drill into a per-PLC faceplate. Bind each control to a tag from the matching connection.
8. Compile and load. Right-click the S7-1200 CPU → Compile → Hardware (rebuild all). Then Download to device for each CPU. Repeat for the HMI station with the WinCC Runtime Advanced target.
9. Start Runtime. On the PC launch Start → SIMATIC → WinCC Runtime Advanced. The runtime starts with the configured start screen and polls all twelve connections.

PROFINET Configuration & Diagnostics

The S7-1200 PROFINET port supports these services out of the box:

For WinCC Advanced PC Runtime, S7 communication over PROFINET is required. Confirm that "Permit access with PUT/GET from remote partner" is enabled on every CPU, or use the WinCC connection type "S7ONLINE" with the PROFINET interface and the partner IP directly.

Verification Procedure

1. Accessible nodes — TIA Portal → Online → Accessible nodes should list all twelve CPU PROFINET device names with their assigned IPs. If any node is missing, check cable, port LED, and switch port status.
2. PROFINET diagnostics — Right-click each CPU → Online & Diagnostics → PROFINET diagnostics. Confirm port status = "OK", no "Link down" events, no station failure.
3. Connection test — In WinCC Runtime, open Tools → Connection status (or the diagnostic screen). All twelve HMI connections should show status "Connected" with a refresh cycle of 1 s.
4. Tag live update — Force a value in the PLC using a watch table and confirm the value updates in the WinCC screen within two refresh cycles.
5. Load stress test — With all twelve connections live and 50 tags/PLC, confirm WinCC Runtime CPU stays < 60% on a Core-i5 PC and that no connection drops occur over a 24-hour burn-in.

Troubleshooting Matrix

Field-Commissioning Notes

• IP addressing: Reserve the engineering PC IP outside the PLC range (e.g. 192.168.0.250) to prevent accidental clashes.
• Cable management: Keep PROFINET cables separated from VFD power cables by at least 200 mm or use a metallic divider per EN 50174-2.
• Shielding: Use PROFINET connectors with 360° shield termination (6GK1 901-1BB10-2AA0). Floating shields are the most common cause of intermittent PROFINET errors.
• Watchdog: In WinCC Advanced, set the connection timeout to 5 s and the "Behavior on connection failure" to "Show last value" to avoid nuisance alarms during PLC restarts.
• Backup: Export the TIA Portal project archive weekly. The archive includes device names and IP addresses so that a replacement PLC can be commissioned in < 10 minutes.
• Firmware consistency: Keep all twelve CPUs on the same firmware version (e.g. V4.6.0). Mixing V4.4 and V4.6 on the same network can cause subtle PROFINET IO controller behavior differences.

Frequently Asked Questions