Connecting IBH Link S7++ to S7-400: Complete Setup Guide

Overview

The IBH Link S7++ is an industrial protocol converter manufactured by IBH Softec that bridges Ethernet TCP/IP networks to the legacy Siemens MPI, PPI, and PROFIBUS fieldbuses used by the SIMATIC S7-200, S7-300, and S7-400 controller families. For maintenance engineers, it provides a low-cost fallback path when the primary Ethernet CP (for example CP443-1) is unavailable, or when a programming device has only a LAN port and the physical MPI/PROFIBUS connector is unreachable, occupied, or broken. The adapter ships with a configuration CD containing the IBHNet device driver, a Windows configuration utility, and printable PDF manuals.

For redundant S7-400H systems built around two CPU 414-4H controllers synchronized through fiber-optic links and communicating to the plant LAN via CP443-1 modules, the IBH Link S7++ is typically deployed as a permanent engineering access point mounted inside the cabinet. It connects to the MPI/DP port of one or both H-CPUs using a standard PROFIBUS cable with D-sub connectors, and presents itself on the engineering network as a normal Ethernet node. From the programmer's perspective, the laptop sees a virtual MPI/PROFIBUS node, and STEP 7 / SIMATIC Manager behaves exactly as if a real MPI cable were plugged into the PG.

This guide walks through the complete commissioning path: from the first power-on of the adapter, through Windows PG/PC interface setup, to a verified online session against an S7-400 / S7-400H target. It is written for engineers who already know how to work with SIMATIC Manager but need the exact sequence to make the IBH Link S7++ work as the access hardware.

Prerequisites

Before starting, verify the following items are on site and in working order:

• IBH Link S7++ unit with power supply wiring (typically 24 V DC, 2 W maximum). Power is usually tapped from the cabinet 24 V rail.
• IBH installation CD supplied with the unit. The CD contains the IBHNet driver, the IBH Link configuration tool, the S7ONLINE redirector, and PDF manuals.
• PROFIBUS cable with 9-pin D-sub male on the adapter side and the matching connector required by the CPU MPI/DP socket (typically 9-pin D-sub female with terminating resistor switch). Keep the cable under 5 m for reliable MPI operation; PROFIBUS segments up to 1,000 m at lower baudrates are supported by the adapter's DP mode.
• Ethernet patch cable (RJ45, Cat 5e or better) to connect the adapter to the PG laptop or to the engineering switch.
• PG/PC laptop with STEP 7 V5.5 (SIMATIC Manager) and the IBHNet driver installed. Windows 7, Windows 10 (32-bit and 64-bit versions), and Windows Server editions are supported by the driver; verify the installer matches your OS architecture.
• STEP 7 project archive (.zip or .s7p) of the target S7-400 station if you intend to upload from the controller. For S7-400H systems, you need the corresponding H-station project to load the full redundancy software.
• Administrative rights on the Windows laptop to install the IBHNet driver and to modify the PG/PC interface (Set PG/PC Interface) registry entries.
• Network parameters agreed with the plant network administrator: IP address, subnet mask, default gateway for the IBH Link S7++, and a free IP for the laptop in the same subnet if direct crossover is used.

Hardware Topology and Wiring

The IBH Link S7++ sits between the engineering network and the PLC fieldbus port. The two physical interfaces are galvanically isolated from each other and from the 24 V supply. The unit provides a single MPI/DP connector (9-pin D-sub female) and a single 10/100 Mbit Ethernet RJ45 port.

The standard topology for a single-CPU S7-400:

[Inline SVG topology]
PG laptop (Ethernet, RJ45) → engineering switch → IBH Link S7++ (24 V DC powered) → PROFIBUS/MPI D-sub cable → S7-400 CPU MPI/DP port (rack 0, slot 3). Optional parallel path: CP443-1 → plant LAN.

The standard topology for an S7-400H station retains the same access path; only the target PLC changes:

[Inline SVG H-system topology]
Redundant 414-4H pair (rack 0, slots 3 and 4) with two MPI/DP ports. IBH Link S7++ connected to CPU 0 MPI/DP. CPU 1 MPI/DP reserved for an HMI panel or handheld PG. Fiber-optic sync link between H-CPUs remains untouched.

Wiring checklist before powering the adapter:

1. Mount the IBH Link S7++ on a 35 mm DIN rail inside the cabinet. Allow at least 30 mm clearance above and below for ventilation.
2. Apply 24 V DC to the power terminals. The PWR LED on the front should illuminate solid green within two seconds.
3. Connect the PROFIBUS cable between the adapter's 9-pin D-sub port (MPI/DP) and the CPU's MPI/DP socket. If the IBH Link is the only device at the end of the segment, leave the adapter's terminating resistor engaged (most units have a slide switch next to the D-sub).
4. Connect the RJ45 patch cable from the adapter's LAN port to the engineering switch or directly to the PG laptop (use a crossover cable for direct connection if the laptop NIC does not support Auto-MDIX).
5. Verify link LEDs: the LAN LED on the adapter should be lit or flashing, indicating Ethernet physical layer is up.

The PROFIBUS connector pinout that the adapter exposes is the standard PROFIBUS RS-485 pin assignment on a 9-pin D-sub female:

IBH Link S7++ Initial Configuration

The adapter ships with a default IP address. Document the address printed on the CD sleeve or on the side label of the unit, then proceed as follows.

1. Power the adapter and wait until the SYS LED shows steady operation (a healthy unit typically shows a slow heartbeat or steady green; refer to the unit front-panel legend for the exact pattern).
2. Configure the laptop NIC with a static IP in the same subnet as the adapter (for example, if the adapter default is in 192.168.1.xxx, set the laptop to 192.168.1.100, mask 255.255.255.0). Disable any other active network adapters to avoid routing conflicts during commissioning.
3. Browse to the adapter's web interface by entering the default IP into a web browser. The web UI prompts for a username and password; the defaults are printed in the unit manual (commonly admin / admin on older firmware, or blank on first-login units that force a password change). Replace these credentials before connecting to a production network.
4. Set the fieldbus mode on the configuration page: choose MPI for the CPU 414-4H MPI port (default baudrate 187.5 kbit/s) or PROFIBUS-DP Master if you want to use higher baudrates (up to 12 Mbit/s) for S7-400 stations. For redundant S7-400H stations, leave the fieldbus type set to MPI unless your project specifically enables PROFIBUS on the H-CPU MPI/DP port.
5. Assign a permanent IP, subnet mask, and (if required) default gateway. Save and apply; the adapter reboots within ~10 seconds.
6. Update firmware if the CD or the manufacturer site ships a newer revision. The web UI typically exposes an "Upload firmware" button under the System menu. Record the firmware version in your asset register.
7. Disable unused services (for example, the integrated web server on the public side, FTP, or Telnet) if your security policy prohibits them. The IBH Link S7++ supports only the services required for S7 routing by default; remove what you do not need.

PG/PC Interface Configuration in Windows

STEP 7 / SIMATIC Manager accesses the IBH Link S7++ through a logical access point called S7ONLINE. The Windows-side driver (IBHNet) registers itself as a new PG/PC interface; you must select it once and bind it to S7ONLINE. The procedure is documented in the manufacturer-supplied IBH S7++ Link configuration note and the IBH Softec operation manual.

1. Open the Windows Control Panel and launch Set PG/PC Interface (German: PG/PC-Schnittstelle einstellen). On 64-bit Windows the program is typically located under Control Panel → Siemens Automation → Set PG/PC Interface.
2. In the Access Point of the Application dropdown, select S7ONLINE.
3. In the Interface Parameter Assignment Used dropdown, the IBHNet driver appears with a name such as IBHNet (MPI) or IBHNet (Ethernet). Choose the entry that matches the fieldbus mode you selected on the adapter. For MPI access to the S7-400 CPU, pick IBHNet (MPI).
4. Click Properties. The IBHNet driver dialog opens. Enter the IP address of the IBH Link S7++ (the static address assigned in the previous section). Confirm the MPI address of the laptop virtual PG node — 0 is the standard; do not duplicate the CPU MPI address (default 2 for an S7-400, configurable per HW Config).
5. Set the highest MPI station address (HSA) to 31 (the IBHNet driver default), or to the maximum address configured on the bus.
6. Click OK to apply. Windows may prompt you to confirm the change of the S7ONLINE access point — confirm.

The relationship between access points and physical interfaces is summarized below:

Default MPI timing parameters the driver uses when scanning through the adapter:

Simatic Manager Online Connection

With the driver bound, the SIMATIC Manager can reach the S7-400 station through the IBH Link as if a native MPI cable were attached. The steps below assume the standard STEP 7 V5.5 / Siemens Industry Online Support project flow.

1. Launch SIMATIC Manager.
2. Open the target STEP 7 project that matches the station. If you only want to upload the current program from the PLC (because the project was lost or never archived), proceed directly to the upload steps in the next section.
3. In the project tree, right-click the SIMATIC 400 station and choose PLC → Download (or PLC → Upload Station to PG).
4. SIMATIC Manager opens the Select Target Station dialog. Because the IBHNet driver is bound to S7ONLINE, the dialog scans the virtual MPI subnet over Ethernet and lists reachable stations.
5. Select the target CPU (the dialog reports the MPI address and rack/slot, e.g. MPI address 2 / Rack 0 / Slot 3 for a CPU 414-4H in slot 3 of rack 0). Confirm.
6. STEP 7 performs an online/offline comparison and prompts you to continue if differences are detected. Accept if you intend to overwrite the offline project.
7. After download completes, the CPU restarts if the download changed the hardware configuration; otherwise it stays in RUN.

For S7-400H stations, the dialog may show two CPUs with consecutive MPI addresses (for example 2 and 3). Pick the one currently serving as master; STEP 7 routes the download to both H-CPUs through the redundancy firmware.

S7-400H Redundancy Considerations

Working through an IBH Link on a redundant S7-400H system introduces a few constraints that do not exist on a single S7-400 station.

Connection target. The IBH Link cable should land on the MPI/DP port of the CPU you want to address. By convention, connect to CPU 0 (rack 0, slot 3) — the master under normal operation. Both H-CPUs are reachable in turn, but only the master actively runs the user program; the standby CPU is in sync and ready for hot take-over.

Link-up to the standby. If the master CPU fails and the standby takes over, the IBH Link connection drops momentarily (MPI/DP port on the failed CPU goes silent) and resumes on the surviving CPU within seconds. To avoid spurious operator messages, run the engineering software in go online mode only when necessary, or use STEP 7 automatic reconnect.

Download to H-system. When you download a modified HW Config or user program to an H-station, STEP 7 performs the download twice — once to each CPU — and verifies the redundancy consistency before activating the change. This means the IBH Link must be reachable from both CPUs. With a single IBH Link connected to CPU 0 only, you must use the H-CPU internal routing to reach CPU 1 (slot 4). STEP 7 handles this automatically once the H-station is online.

Diagnostic buffer. Open PLC → Diagnostics/Settings → Diagnostic Buffer in SIMATIC Manager to read the CPU event log. For H-systems, both CPUs' buffers are accessible from the online view; select the desired CPU from the dropdown.

Redundancy states reported by the H-system that are visible through the IBH Link:

Project Upload and Download Procedures

The IBH Link S7++ is most often used to upload the live project from the PLC when the offline archive is missing or suspected to be out of date. The procedure is identical to that used over a direct MPI cable.

1. In SIMATIC Manager, choose PLC → Upload Station to PG.
2. Select the target CPU in the Select Target Station dialog (the IBHNet scan will list it).
3. STEP 7 reads the system data blocks (SDBs), the hardware configuration, and the user program blocks from the CPU and assembles a new offline project.
4. Save the new project immediately (File → Save As) and back it up to the engineering file server.

To download a known-good project back to the PLC as a fallback when the CP443-1 path is broken:

1. Open the offline project in SIMATIC Manager.
2. Compile the HW Config (Station → Consistency Check → Compile) and the user program (PLC → Compile All).
3. Right-click the station and select PLC → Download. Confirm the target station in the dialog.
4. Monitor the download progress in the status bar. For H-systems, STEP 7 reports Download to CPU 0 — OK followed by Download to CPU 1 — OK.

For a complete station archive, also download the symbolic comments and the source files. STEP 7 keeps these on the engineering laptop; they are not stored in the CPU itself. After upload, re-create the symbol table and the source STL/SCL files from the archive if they were lost.

Verification and Diagnostics

After commissioning, verify that the access path is healthy using the following checks:

1. Ping the adapter from the laptop: ping <adapter-IP>. Sub-millisecond response on a local Ethernet confirms the TCP path.
2. Open the adapter web UI and check the fieldbus status page; the unit should report the connected MPI address, baudrate, and bus error counters.
3. Run SIMATIC Manager → PLC → Diagnostics/Settings → Diagnostics; verify the CPU responds with its order number, firmware version, and module status.
4. Read the diagnostic buffer; the most recent entries should be informational only (cycle time, restart events). Any bus-related entries with error codes SF, BF, or DP fault indicate wiring or termination problems.
5. Test a small block download: add a comment to an existing FC, save, download, and confirm the online view shows the new comment. This round-trip proves the full read/write path through the adapter.
6. Verify redundancy for H-systems by reading PLC → Redundancy information; both CPUs should report role Master and Standby respectively, and link status OK.

The front-panel LEDs on the IBH Link S7++ give a quick at-a-glance health check. Typical meanings:

Troubleshooting Matrix

FAQ