Adding Allen-Bradley PLCs to WinCC Flexible V11 SCADA

Adding Allen-Bradley PLCs to a WinCC Flexible V11 SCADA Connected to Mitsubishi PLCs

Problem Definition: Mixed-Vendor PLC Network on a Siemens SCADA

An existing WinCC Flexible Advanced project (TIA Portal V11 SP2, build 11.0.2.0) is polling five Mitsubishi MELSEC PLCs over Ethernet using the built-in Mitsubishi MC TCP/IP channel. The engineer now needs to integrate Allen-Bradley controllers — typically ControlLogix (1756-L8x), CompactLogix (5069-L3x), MicroLogix (1769-L3x), or SLC 500 (1747-L5x) — into the same operator visualization.

The integration fails at the Connections editor because WinCC Flexible V11 SP2 ships without a native Allen-Bradley communication channel for DF1 serial, EtherNet/IP (CIP), or ControlLogix tag access. The only driver slots exposed in the project tree are:

• SIMATIC S7 – MPI / PROFIBUS-DP / ISO-on-TCP (port 102)
• SIMATIC HMI HTTP – port 80, vendor-neutral REST polling
• Mitsubishi MC TCP/IP – port 5000 (1E frame) / 5001 (3E frame)
• Modicon Modbus TCP – port 502, Master / Slave
• OPC DA Client – DCOM-based, vendor-neutral bridge

There is no Allen-Bradley, Rockwell, EtherNet/IP, DF1, ControlLogix, or CompactLogix channel in the Connections editor. Selecting any of these strings returns Connection not possible on this combination. This article documents the five engineering options, the licensing constraints of each, and the commissioning checklist required to put a mixed Mitsubishi + Allen-Bradley network into production.

Native Protocol Support in WinCC Flexible V11 SP2

The Communication manual for WinCC Flexible 2008 SP2 / TIA V11 enumerates every supported PLC driver. The subset relevant to a mixed-vendor migration is shown in Table 1.

Table 1 — WinCC Flexible V11 SP2 PLC connection slots

Allen-Bradley EtherNet/IP (TCP/UDP 44818 for explicit messaging, UDP 2222 for I/O) and DF1 full-duplex serial (RS-232 / RS-422) are not implemented. The OPC DA Client slot is the only vendor-neutral entry point that can bridge to a Rockwell controller if an external OPC server is present on the network.

Why Direct Allen-Bradley Integration Fails in WinCC Flexible

Allen-Bradley EtherNet/IP uses the Common Industrial Protocol (CIP) as defined in ODVA Volume 1. CIP is message-based, object-modeled, and routes through CIP-class/instance/attribute addressing (e.g., class 0xF5 instance 1 attribute 1 = system time). WinCC Flexible tag addressing, by contrast, assumes a flat register-and-coil model:

• Mitsubishi: D0, M100, X10, Y20, W0
• Siemens: DB100.DBW0, M0.0, I0.0, Q0.0

Adding CIP reads would require a new driver stack with CIP routing table parsing, EDS-file interpretation, and connection-class management (class 1 I/O, class 3 explicit). Siemens delivered Allen-Bradley support only in WinCC Professional V13 SP1 and later, channel name Allen-Bradley ControlLogix, and in WinCC V7.4 + AS-OS Engineering via the AllenBradleyEIP third-party channel. WinCC Flexible never received this driver because the product line was declared end-of-life with the TIA Portal V13 rollout.

Architecture Options for Mixed Mitsubishi + Allen-Bradley Networks

Five viable topologies exist. Each is rated in Table 2 on engineering effort, cost, and risk.

Table 2 — Comparison of mixed-vendor SCADA architectures

Option 1: OPC DA Gateway (Recommended Path)

This topology preserves the existing WinCC Flexible V11 SP2 project and inserts a commercial OPC server between the Allen-Bradley PLC and the SCADA.

Allen-Bradley PLC ── EtherNet/IP (TCP 44818) ──> OPC Server (KEPServerEX V6)
                                                          │
                                                          └── OPC DA (DCOM) ──> WinCC Flexible OPC Client
                                                                                       │
Mitsubishi PLCs ── MC TCP/IP (TCP 5001) ──> WinCC Flexible MC TCP/IP channel ─────────┴──> WinCC Flexible Runtime

Figure 1 — OPC DA gateway topology

Supported OPC Servers

Table 3 — OPC servers with Allen-Bradley support

KEPServerEX Configuration (ControlLogix Example)

1. Add Channel → Allen-Bradley ControlLogix Ethernet
2. Set Adapter IP to the ControlLogix CPU (e.g., 192.168.10.20)
3. Slot 0 = CPU module (1756-L85E)
4. Add Device → CPU slot 0; leave slot number blank if rack-mounted
5. Auto-create tags from an L5X export, or browse Controller Tags in the OPC quick client
6. Enable Auto-Demote on Communication Error = 0 to force re-subscribe on transient faults
7. Set the scan rate to 100 ms for control-loop tags, 1000 ms for status tags

WinCC Flexible V11 SP2 OPC Client Configuration

1. In the project tree, right-click Connections → Add new connection
2. Driver: OPC (channel name displays as OPC)
3. OPC Server: click Browse, select Kepware.KEPServerEX.V6 from the OPCEnum list
4. Click Browse tags to open the Allen-Bradley tag namespace
5. Map each OPC tag to an HMI tag (right-click → Link to HMI tag)
6. Compile → RT → Download to WinCC Runtime

Option 2: Dedicated Protocol-Conversion Gateway

A standalone gateway hardware device translates EtherNet/IP on the Allen-Bradley side to Modbus TCP or Mitsubishi MC TCP on the WinCC side. WinCC Flexible V11 then polls the gateway using its existing Modbus TCP or MC TCP driver — no new channel required.

Table 4 — EIP protocol conversion gateways

Configuration Steps for a ProSoft PLX31-EIP-MBTCP

1. Configure the gateway IP (default 192.168.1.1) via the integrated web UI
2. Set the EIP scanner IP to the ControlLogix CPU
3. Map 100 Modbus holding registers (400001–400100) to 100 CIP instance/attribute pairs
4. In WinCC Flexible: Connections → Add → Modicon Modbus TCP → gateway IP
5. Define tags with Modbus address range 400001–400100
6. Set the WinCC poll rate to 250 ms minimum for stable CIP traffic

Advantages: no software change on the SCADA; deterministic latency; galvanic isolation between vendors. Disadvantages: additional hardware cost (USD 800–2500); manual tag mapping; debugging requires gateway log access.

Option 3: Dual-NIC PC with Isolated Subnets

If the WinCC Flexible project can be split, one WinCC Runtime serves the Mitsubishi MC network and a second instance communicates with the Allen-Bradley PLCs through an OPC client. Two network interface cards isolate the broadcast domains.

PC hardware requirement: dual-NIC industrial PC (e.g., Siemens SIMATIC IPC547G or Advantech IPC-610). Each NIC connects to a separate VLAN or physical switch.

NIC1 (192.168.1.x) ──> Mitsubishi PLC subnet ──> WinCC Runtime A (MC TCP driver)
NIC2 (192.168.10.x) ──> Allen-Bradley PLC subnet ──> Local OPC Server ──> WinCC Runtime B (OPC client)

Figure 2 — Dual-NIC isolated subnets

Implementation Steps

1. Install two physical NICs; assign NIC1 to 192.168.1.0/24, NIC2 to 192.168.10.0/24
2. Disable Windows routing between the two NICs to enforce isolation
3. Install the OPC server (KEPServerEX) on the same PC, bound to NIC2
4. Run two instances of WinCC Flexible Runtime on separate Windows services
5. Use a tag-multiplexer (WinCC Flexible internal tag + script, or third-party) to merge tag data into a single HMI screen set
6. Optionally publish WinCC Flexible as an Sm@rtServer so a third operator station pulls screens from either runtime

Option 4: Upgrade to WinCC Professional V13 SP1 with Native EtherNet/IP Driver

WinCC Professional V13 SP1 and later include a native Allen-Bradley EtherNet/IP channel. The migration path from a WinCC Flexible V11 SP2 project is documented below.

Migration Steps

1. Open the WinCC Flexible V11 SP2 project in TIA Portal V13 SP1 (Siemens provides a migration wizard)
2. Accept the migration report; review warnings about VBScript custom functions and unsupported ActiveX controls
3. Add the Allen-Bradley ControlLogix driver in the Connections editor
4. Configure IP, slot, and CIP path of the Logix controller (e.g., 192.168.10.20,1,0 for backplane slot 0)
5. Browse Logix tags directly into the HMI tag table
6. Re-validate all VBScript functions (WinCC Professional uses a stricter VBScript sandbox)
7. Compile → RT → Download to the new WinCC Professional Runtime

Cost & Risk

WinCC Professional RT is priced per tag count and is approximately 3–5× the cost of WinCC Flexible Advanced. Migration typically requires 2–5 engineering days for a 1,000-tag project. This option is recommended for greenfield projects or when the existing WinCC Flexible project is approaching end-of-life anyway.

Option 5: Replace SCADA with a Multi-Protocol Platform

If long-term multi-vendor support is required, evaluate SCADA platforms with native drivers for both vendor families.

Table 5 — Multi-protocol SCADA platforms

A pilot deployment of Ignition Perspective + EIP driver module + MC TCP driver typically takes 3–5 engineering days for a five-PLC Mitsubishi + multi-PLC Allen-Bradley scope. This is the most flexible long-term option but constitutes a full SCADA replacement.

Licensing Considerations for WinCC Flexible / TIA Portal

WinCC Flexible and TIA Portal are licensed per power pack. The license key encodes:

• Runtime version (e.g., WinCC Flexible 2008 SP2 RT 1024 PowerTags)
• Optional add-ons (S7-300/400 F, Audit, Sm@rtAccess, OPC Server)
• Maximum tag count

The WinCC Flexible OPC client slot is included in every WinCC Flexible Advanced license. Connecting to a third-party OPC server does not require an additional Siemens license — only the OPC server itself must be licensed. For WinCC Professional V13 SP1 and later, the Allen-Bradley EtherNet/IP channel does not require a separate add-on license; it is included in the base RT license. See Licensing STEP 7 and WinCC - TIA Portal for the V20 license matrix.

For KEPServerEX V6, the Allen-Bradley ControlLogix Driver is a separate per-driver license (~$750 standalone, ~$1800 as part of the IoT Gateway bundle). Without that driver enabled, the OPC namespace will not expose any Logix tags.

Verification and Commissioning Checklist

Before declaring the mixed network production-ready, perform the seven steps in Table 6.

Table 6 — Commissioning checklist

Troubleshooting Matrix

Table 7 — Troubleshooting matrix

Engineering Recommendations

For a brownfield installation where the existing WinCC Flexible V11 SP2 project must be preserved and the engineer only needs to expose 50–200 Allen-Bradley tags, the OPC DA gateway (Option 1) delivers the lowest total cost of ownership. KEPServerEX V6 with the Allen-Bradley ControlLogix driver covers ControlLogix, CompactLogix, and MicroLogix tag access through a single OPC namespace.

For greenfield installations with a 5-year lifecycle, the WinCC Professional V13+ upgrade (Option 4) eliminates the OPC bridge entirely and provides native CIP routing, redundancy, and audit — at the cost of re-engineering the project.

For multi-site rollouts where OPC licensing becomes expensive, the protocol conversion gateway (Option 2) at each site delivers deterministic latency at a fixed per-site hardware cost.