Wiring S5 CP143 SSV104 to RJ45 SCADA: ITP vs AUI Solutions

Problem Overview

Migrating a SCADA workstation away from legacy SIMATIC NET hardware while leaving an installed base of SIMATIC S5-115U and S5-135U controllers untouched is a recurring brownfield problem. Each PLC terminates Ethernet through a CP143 communications processor that speaks the SIMATIC NET ISO transport protocol (ISO 8073 Class 4) over a 10 Mbit/s H1 (IEEE 802.3 10BASE5/10BASE2) backbone. The H1 fan-out device, the SSV104, is a pure AUI multiport transceiver - it has no twisted-pair MAU and no Layer-2 intelligence. The legacy SCADA PC carried a CP1314 ISA card with an AUI port and the SIMATIC NET ISO stack.

The instinctive workaround on a modern PC is to drop an ITP cable (for example 6XV1 850-2LH10) between the new PC's RJ45 jack and the SSV104's 15-pin Sub-D, then load the SIMATIC NET ISO transport driver on the onboard NIC. That configuration will never bring up a link. The ITP cable assumes Siemens ITP signalling on both ends; the SSV104 only exposes AUI; and the RJ45 NIC only speaks 10BASE-T/100BASE-TX MLT-3. No physical layer is shared. This reference walks through the underlying interface mismatch and then details the two field-proven migration paths that keep the CP143 fleet and the SSV104 in place.

Current vs Proposed SCADA Architecture

The original wiring is fully AUI from the CP143 to the SSV104 to the CP1314 in the SCADA PC. The naive migration replaces only the SCADA PC and substitutes an RJ45 patch for the AUI drop. The corrected options preserve the SSV104 but introduce either a PCIe card with an AUI port on the new PC, or a small media converter at the SSV104 end.

Why a Direct ITP Cord Does Not Work

Three incompatible physical layers are in play. Each fails on its own terms.

The SSV104 is transparent at the MAC layer - it does not encode or decode any line signal. It just relays AUI between its ports. If the SCADA side never presents valid AUI signals, every CP143 in the star sees a dead segment. Likewise, an RJ45 NIC never sees valid 10BASE-T link pulses, so it never declares link up. Both ends assume the other end is faulty. The cable is the least of the problem; it is the absence of a media converter that breaks the chain.

SSV104 Interface Analysis

The SSV104 (catalog 6GK1 104-0AA00) is an AUI multiport transceiver and star hub. Each of its ports is a female 15-pin Sub-D wired per IEEE 802.3 Section 7 (AUI). The four data lines are DO+/-, DI+/-, and the control lines are VC (violation / collision presence) and VP (voltage plus, +12 V to power external transceivers if any). It is electrically transparent and does not contain a TP MAU or a managed Ethernet switch. It cannot auto-negotiate; it cannot bridge between AUI and TP. It simply repeats whatever Manchester signal it sees on one port onto all the others.

The CP143 connects to the SSV104 with a standard AUI drop cable, typically 6XV1 850-0AH10 (or equivalent). The cable carries the four data pairs and the +12 V VP power line. The legacy CP1314 in the old SCADA PC also accepted an AUI drop. The new PC must therefore provide either an AUI port of its own or an AUI-to-TP media converter somewhere on the segment. The original SIMATIC NET manual chapter that documents this media-conversion guidance is the SIMATIC NET Twisted-Pair and Fiber-Optic Networks manual, section 6.5.

Solution Option A - CP1613 A2 in the SCADA PC

The simplest drop-in is the CP1613 A2 (catalog 6GK1 161-3AA01), a PCIe x1 card with both an AUI Sub-D 15 port and an RJ45 (10/100 Mbit/s) port on the bracket. The card is supported by the SIMATIC NET PC Software suite, which loads the ISO transport stack directly onto it. The card appears in Windows as a SIMATIC NET device rather than a generic NIC and is configured through the SIMATIC NET Configuration Console.

Field wiring for Path A:

1. Power down the new SCADA PC. Fit the CP1613 A2 in a free PCIe slot.
2. Connect an AUI drop cable (for example 6XV1 850-0AH10) from the CP1613 A2's AUI port to one of the SSV104's AUI ports.
3. Leave the ten CP143s untouched. Their AUI drops into the remaining SSV104 ports.
4. Boot Windows. Install SIMATIC NET PC Software with SOFTNET IE S7 (the S5/S7 communication component) and the OPC server.
5. In Configuration Console, bind the CP1613 A2 to ISO Transport mode. Set a local MAC address (or accept the card default) and a TSAP - see the software section below.

The CP1613 A2 also has an RJ45 port. If you later migrate the SCADA side to a modern managed switch, the card can be reconfigured as a TP node without removing it. That gives you a clean upgrade path away from the SSV104 when the CP143 fleet is eventually retired.

Solution Option B - MINI UTDE Media Converter

If installing a PCIe card is not an option - for instance because the SCADA PC is a sealed industrial panel without expansion slots, or because the IT department prefers to use the standard onboard NIC - use a MINI UTDE AUI-to-TP media converter. The MINI UTDE is a Siemens SIMATIC NET media converter intended for terminal/drop devices. It is a small in-line box with an AUI Sub-D 15 on one side and an RJ45 (10 Mbit/s) on the other, and it draws its +12 V power from the AUI VP line.

Field wiring for Path B:

1. Connect the MINI UTDE's AUI port to one of the SSV104's AUI ports via a standard AUI drop.
2. Connect the MINI UTDE's RJ45 port to a standard unmanaged or managed Ethernet switch (or directly to the SCADA PC NIC with a patch cable).
3. Connect the ten CP143s to the remaining SSV104 ports as before.
4. On the SCADA PC, install SIMATIC NET PC Software with SOFTNET IE S7 and bind the onboard NIC (or the switch port NIC) to ISO Transport mode.

Because the MINI UTDE terminates at 10 Mbit/s only, the SCADA side switch and NIC must auto-negotiate down to 10 Mbit/s full or half duplex. Modern NICs auto-negotiate correctly, but some managed switches have the port-speed fixed at 100 Mbit/s by default - verify the port is set to Auto or 10 Mbit/s.

Solution Comparison

For a single SCADA PC and a 10-CP143 fleet, Path A is the lowest-risk and most supportable answer. The CP1613 A2 is documented as a connection endpoint for SSV104-style AUI segments and is officially supported by SIMATIC NET PC Software. Path B is acceptable where the SCADA PC hardware cannot accept a card or where the migration is expected to be temporary.

Software Stack - SIMATIC NET SOFTNET IE S7

Whichever path is chosen, the SCADA PC requires the SIMATIC NET PC Software stack with the S7/S5 communication driver and the OPC server. The relevant component is the SOFTNET IE S7 family of drivers, which includes the ISO transport protocol needed to speak to a CP143. It is not the same product as SOFTNET-IE S7 Lean or SOFTNET-IE PN - those bundles are TCP/IP-only and will not load the ISO transport stack.

Installation order:

1. Install SIMATIC NET PC Software first; this places the Configuration Console, the OPC DA server (ProgID OPC.SimaticNET.DA) and the OPC UA server.
2. Install the SOFTNET IE S7 license (an electronic license key, usually delivered as a License Key Disk or through the Web License Manager).
3. Reboot. Open SIMATIC NET Configuration Console as Administrator.
4. Under Modules, locate the CP1613 A2 (or the NIC used in Path B). Right-click -> Properties -> bind to ISO Transport.
5. Assign a TSAP (Transport Service Access Point). For CP143 connections the convention is 01.01 for the first slot, 02.01 for the second, and so on. Match the CP143's COM 143 configuration exactly.

On the S5 side, open STEP 5 and the COM 143 configuration tool. Each CP143 must have at least one configured ISO transport connection pointing at the SCADA PC's MAC address and TSAP. The standard FETCH active and WRITE active connection types are typical for SCADA poll/command traffic. The same ISO transport handshake pattern that the SCADA PC uses to talk to an S5 CP143 is also documented for the reverse direction (S5 as client, modern controller as server) in the Siemens cross-generation example 109482475 - Ethernet Communication between SIMATIC S5 and a SIMATIC S7-1500.

OPC and SCADA Tag Integration

Once the ISO transport connection is up, expose the S5 data through the SIMATIC NET OPC DA server. Modern SCADA packages - WinCC, WinCC Professional, Ignition, iFIX, Citect, FactoryTalk View - include an OPC DA client. Point the client at ProgID OPC.SimaticNET.DA on the local host. Each S5 data block item is referenced with the SIMATIC NET item syntax:

S5:[ConnectionName]DB100,DBW0
S5:[ConnectionName]DB200,DBB5
S5:[ConnectionName]E0.0
S5:[ConnectionName]A4.7
S5:[ConnectionName]MW100

For SCADA packages that prefer OPC UA, the SIMATIC NET OPC UA server (included with SIMATIC NET V14+) exposes the same data tree as DA. Alternatively a third-party OPC DA-to-UA bridge can be inserted in front of the SIMATIC NET DA server.

When migrating, replace the old CP1314 driver configuration in the SCADA project with the new SIMATIC NET OPC items. Tag names can usually be preserved, but verify that bit-level addresses (for example E0.0) map cleanly between the old CP1314 OPC server and the new SIMATIC NET OPC server; some legacy servers used 1-based numbering, SIMATIC NET uses 0-based.

Migration Procedure

Use this ordered procedure for either path. Steps marked [A] apply only to the CP1613 A2 path, steps marked [B] only to the MINI UTDE path.

1. Inventory the existing SSV104 ports and label each drop cable at both ends. Photograph the SSV104 before any change.
2. Confirm the SCADA PC hardware: PCIe slot available? [A] Onboard NIC free? [B]
3. Order components: CP1613 A2 6GK1 161-3AA01 and SOFTNET IE S7 license [A], or one MINI UTDE media converter and SOFTNET IE S7 license [B].
4. Plan a SCADA outage window. Even though the CP143s keep running, the SCADA loses visibility during the cut.
5. Power down the SCADA PC. Fit the CP1613 A2 [A] or free the onboard NIC port [B].
6. Connect AUI drop from SSV104 to CP1613 A2 [A] or to MINI UTDE [B]. Connect RJ45 patch from MINI UTDE to the switch/NIC [B].
7. Boot Windows. Install SIMATIC NET PC Software and the SOFTNET IE S7 license. Reboot.
8. Open SIMATIC NET Configuration Console. Bind the CP1613 A2 [A] or onboard NIC [B] to ISO Transport. Set local TSAP 01.01.
9. Verify the COM 143 configuration in STEP 5. Each connection must point at the new SCADA PC's MAC and TSAP.
10. Open the SIMATIC NET Connection Diagnostics tool. Confirm all ten CP143 connections report Established.
11. Reconfigure the SCADA project: replace the old CP1314 driver with the SIMATIC NET OPC DA client. Validate tag reads against each of the ten PLCs.
12. Perform a write test from SCADA to a non-critical S5 tag (for example a marker word). Confirm the value changes in STEP 5 online monitor.
13. Place the SCADA back in service and monitor for at least one shift before closing the migration.

Verification and Commissioning

Use this checklist during commissioning:

Troubleshooting Matrix

FAQ