Connecting LOGO! 0BA7 to KTP 900 Basic via S7-200 Driver

Overview

Siemens LOGO! 0BA7 (the so-called "LOGO! 7" generation, 6ED1052-1xx00-0BA7 family) communicates using the S7-200 protocol over its integrated Ethernet port, not the native "LOGO!" driver that appears in TIA Portal V15 for the newer 0BA8 generation. When a KTP 900 Basic (6AV2123-2JB03-0AX0) panel is configured against a 0BA7 CPU, the project must select the SIMATIC S7-200 connection driver — selecting the LOGO! driver in TIA Portal will compile cleanly but will not establish runtime communication. The 0BA8 (LOGO! 8) supports both the dedicated LOGO! driver and the S7-200 driver; 0BA7 only supports the S7-200 driver path.

This reference covers the complete integration path: the physical Ethernet topology, the S7-200 connection block in TIA Portal V15 (and compatible V15.1 / V16 / V17 projects), the LOGO! Variable Memory (VM) mapping that the S7-200 driver expects, tag declarations on the HMI side, and a verification checklist based on diagnostic indicators visible in the panel's connection status.

Prerequisites

Why the LOGO! Driver Fails on 0BA7

The "LOGO!" connection in TIA Portal was introduced specifically for the 0BA8 generation. The 0BA8 firmware exposes a connection service compatible with the LOGO! driver block. The 0BA7 firmware, despite having the same RJ45 footprint, exposes only an S7-200 compatible communication server. When the HMI is configured with a LOGO! connection against a 0BA7 CPU, the panel sends the LOGO! connection-establishment telegram; the 0BA7 replies with a TSAP/port mismatch or no response at all, and the panel reports "Connection interrupted" (Event 140001 / 140002 / 140003 / 140004 in the HMI diagnostic buffer).

The SIMATIC S7-200 driver in TIA Portal issues an S7 communication request to the standard S7 port 102 (ISO-on-TCP / RFC 1006), which the 0BA7 firmware accepts. The same driver is used when a real S7-200 CPU (6ES721x-xxxxx-xxxx) or a compatible S7-200 emulation is the target — the LOGO! 0BA7 is a compatible device from the perspective of this driver.

Network Topology

Both the LOGO! 0BA7 and the KTP 900 Basic expose a single PROFINET (PN) interface. The classic integration is a point-to-point or single-switch Ethernet segment. The IP subnet, gateway, and subnet mask must match.

Direct connection (crossover or auto-MDIX) is acceptable for commissioning. In production, route through a managed switch and assign fixed IPs in the LOGO! 0BA7 web configuration (Tools → Ethernet → IP Address) and in the TIA Portal HMI device configuration (Display → Network settings).

Configuring the LOGO! 0BA7 Network

1. Connect the LOGO! 0BA7 to your engineering PC and open LOGO!Soft Comfort V8.3.
2. Go to Tools → Ethernet Connections (or right-click the device → Properties → Ethernet).
3. Assign a static IP compatible with the HMI's subnet. Example: 192.168.0.10, subnet mask 255.255.255.0, gateway 192.168.0.1.
4. Set the S7 server to enabled (default in 0BA7 firmware). The 0BA7 listens on TSAP 01.00 / local TSAP 02.00 for the S7-200 communication slot — the TIA S7-200 driver uses these by default.
5. Transfer the project to the LOGO! and cycle power if prompted.

Configuring the S7-200 Connection in TIA Portal V15

1. Open the TIA Portal project that contains both the LOGO! 0BA7 station (under "Devices & Networks") and the KTP 900 Basic station.
2. Select the KTP 900 Basic device in the project tree, then double-click Connections.
3. Right-click in the empty connections area and choose Add new connection.
4. From the Communication driver dropdown, select SIMATIC S7-200. Do not select "LOGO!" — that driver is for 0BA8 only.
5. Set the connection partner to the LOGO! 0BA7 station. Configure the partner IP to 192.168.0.10.
6. Leave the rack/slot at the S7-200 defaults (rack 0, slot 0 — LOGO! 0BA7 maps to this logical position for the S7-200 driver).
7. Click Compile and download the HMI project to the KTP 900 Basic.

Connection Block Parameter Summary

Variable Memory (VM) Address Mapping

The LOGO! 0BA7 exposes its internal flags, I/O, and function block parameters in a Variable Memory range that the S7-200 driver can read/write. The S7-200 driver expects the addressing scheme DB1.DBx for byte access (where DB1 is the implicit LOGO! data block) and V<byte>.<bit> for bit access. The complete mapping is:

Example: Reading Output Q1 from the HMI

Q1 in the LOGO! 0BA7 corresponds to bit V1000.0. In TIA Portal, configure an HMI tag as follows:

• Name: LOGO_Q1
• Connection: LOGO_HMI (the S7-200 connection)
• PLC tag / address: %DB1.DBX1000.0 or use the area pointer V syntax if the driver exposes it directly: V 1000.0
• Data type: Bool
• Acquisition mode: Cyclic continuous, 1 s cycle

Example: Writing to Flag M8

• Name: LOGO_M8
• Address: %DB1.DBX4000.7 (byte 4000, bit 7, since M1=V4000.0, M8=V4000.7)
• Data type: Bool

Reading an Analog Input (AI1)

• Name: LOGO_AI1
• Address: %DB1.DBW2000
• Data type: Int (raw 0..1000; convert with HMI scaling if 0..10 V or 4..20 mA is needed)

HMI Tag Configuration in TIA Portal

1. In the project tree, expand KTP 900 Basic → HMI tags.
2. Create a new tag, assign the connection LOGO_HMI.
3. Enter the DB1 address as shown above. The address syntax accepted by the S7-200 driver in TIA Portal V15 is DB1,DBX1000.0 (Bool) or DB1,DBW1000 (Word) — when typed, the compiler converts to the canonical %DB1.DBX1000.0 form.
4. For Word / Int / DWord tags, confirm the byte order is little-endian (S7-200 native). The LOGO! 0BA7 returns words in big-endian for some analog values; if a value reads as 0 or as 256× the expected value, swap the bytes using a "Swap bytes" property on the tag or use a script.
5. Group tags by LOGO! block for easier commissioning: LOGO_I, LOGO_Q, LOGO_AI, LOGO_AQ, LOGO_M.

Verification Procedure

1. Physical layer: Confirm the green link LED on the LOGO! 0BA7 RJ45 and on the KTP 900 Basic PN port are lit.
2. IP layer: From the engineering PC, ping 192.168.0.10 and ping 192.168.0.20. Both must respond before the HMI will connect.
3. LOGO! S7 service: From the PC, run a third-party S7-200 client (e.g. LibNoDave, Snap7) or use the LOGO! web page to confirm the S7-200 server is active.
4. HMI runtime: On the KTP 900 Basic, open Start Center → Settings → Network and confirm the HMI IP and subnet mask.
5. Connection status: Place a status view on a screen that shows the connection state. The "Connected" indicator must change from red to green within ~10 s of HMI startup.
6. Tag live value: Force a digital output in the LOGO! 0BA7 program (e.g. Q1 := TRUE in a test rung) and confirm the HMI tag LOGO_Q1 reflects TRUE within one acquisition cycle.

Troubleshooting Matrix

Communication with Third-Party Gateways

When a non-Siemens gateway sits between the LOGO! 0BA7 and the HMI (for example an HMS Anybus X-gateway or Communicator), the gateway can be configured with the S7-300/400 TCP/IP Master driver on the HMI side, while terminating the LOGO! end as an S7-200 server. The HMS Networks knowledge base article 27220934218642 documents the parameter set required for this topology, including TSAP and slot configuration on the gateway's S7-300/400 master side. This is the documented way to expose LOGO! 0BA7 data to non-S7-200 HMI panels that only support the S7-300/400 driver.

Differences Between 0BA7 and 0BA8 Communication

Performance and Cycle Time

The S7-200 driver on the KTP 900 Basic operates in cyclic acquisition mode. Typical observed values for a 0BA7 → KTP 900 Basic link over a 100 Mbit switch:

• Connection establishment: 2–6 s on cold start
• Single Bool read cycle: 50–150 ms (acquisition cycle dependent)
• Word read of AI1: 80–200 ms
• Multi-tag burst (16 mixed tags): 250–500 ms

For applications requiring faster update, lower the acquisition cycle to 100 ms on critical tags and group slow tags (e.g. parameter words) at 1 s. The LOGO! 0BA7 program cycle is typically 1–10 ms; communication latency is dominated by the HMI polling, not the LOGO! cycle.

Safety and Operational Notes

FAQ