Configuring Multiple ET 200M Stations on S7-300 CPU 317-2 PN/DP

ET 200M Distributed I/O Architecture Overview

The Siemens ET 200M is a modular distributed I/O system built on the S7-300 module catalog. Each ET 200M station is anchored by one IM 153 interface module that converts the S7-300 parallel backplane into a serial fieldbus (PROFIBUS DP or PROFINET). The IM 153 appears to the controller as a logical DP slave or PROFINET IO device, while every signal module plugged behind it behaves as if it were slotted in the central rack. The S7-300 program therefore accesses remote I/O through the same I/Q address space it would use for local racks; the fieldbus is transparent to the cycle.

The CPU 317-2 PN/DP (typical MLFB 6ES7317-2EK14-0AB0, firmware V3.3) carries both a PROFINET interface with an integrated 2-port switch and a PROFIBUS DP master/slave interface. The PN interface as PROFINET IO controller supports up to 256 IO devices, the PROFIBUS DP master supports up to 32 slaves per electrical segment (extendable to 124 with up to 9 RS-485 repeaters). A single CPU can run mixed ET 200M stations on both networks from the same STEP 7 / TIA Portal project, and the choice between PROFIBUS and PROFINET is driven by physical distance, EMI environment, existing cable plant, and whether deterministic PROFINET IRT is required.

Each ET 200M station may be addressed in the S7-300 program through three paths:

• Direct I/O addresses – process image, automatic update on each OB1 scan; fastest path for digital I/O.
• Process image partition (PIP) – I/O updated only on a selected OB, used to keep deterministic I/O with the cycle of a fast OB (e.g. OB35).
• SFC 14 / SFC 15 (DPRD_DAT / DPWR_DAT) – consistent read/write of data blocks larger than 4 bytes; required for most analog modules and for PROFINET submodules with more than 4 bytes.

See the official TIA Portal V20 ET 200M configuration documentation for the architecture summary used by Siemens tooling.

Selecting the Correct IM 153 Interface Module

The IM 153 family is the head of every ET 200M station. The correct variant is decided by fieldbus (PROFIBUS or PROFINET), maximum slot count, hot-swap requirement, and functional safety. There is no "one size fits all" IM 153; getting the order number right is the first practical step.

Active backplane bus modules (6ES7195-7HA00-0XA0 or 6ES7195-7HB00-0XA0) are required between the IM 153-2/-2FO/-4 PN and any module that may be hot-swapped. The IM 153-1 cannot hot-swap regardless of the backplane.

Mechanical Assembly on the S7-300 DIN Rail

ET 200M shares the mechanical footprint of the S7-300, so a standard 35 mm S7-300 profile rail is used. Choose rail length to cover the IM 153 plus every signal module plus a PS 307 power supply with at least 20 mm of spare length for future additions.

1. Snap the DIN rail (e.g. 6ES7390-1AE80-0AA0 530 mm or 6ES7390-1AF30-0AA0 830 mm) to the cabinet backplate and ground it with a low-impedance bond (≤ 1 Ω to cabinet PE).
2. Click the PS 307 onto the leftmost position. Wire L1/N/PE and the 24 V output to the PS 307 L+/M terminals.
3. Connect the S7-300 bus connector between the PS 307 and the IM 153 (mandatory – without it the IM 153 has no backplane power).
4. Click the IM 153 to the right of the PS 307. On the IM 153 set the PROFIBUS address DIP bank (PROFIBUS variant) before applying 24 V.
5. Insert each S7-300 SM/AI/AO/DI/DO/FM/CP module right of the IM 153, in the exact physical order in which they will appear in HW Config / the device view of TIA Portal.
6. Tighten each module's two M4 fixing screws to ≈ 0.8 Nm. Install shielding contact + shield clamp for any analog or encoder cable that uses shielded twisted pair.

Select the PS 307 rating (5 A or 10 A) by summing the backplane currents of every module. The IM 153-2/-2FO/-4 PN draws up to 0.65 A from the backplane, an SM 321 DI 32×DC24V draws 0.03 A, an SM 322 DO 32×DC24V draws 0.08 A, an SM 331 AI 8×AI draws 0.06 A. The PS 307 also feeds the sensor supply (24 V on the front connector of the I/O modules), so leave 25 % headroom for field-side current.

PROFIBUS DP Station Addressing (DIP Switches)

On PROFIBUS variants the station address is set on the 8-way DIP switch bank on the back of the IM 153. The address must be unique on the segment, in the range 1 through 125 (DIP switch 8 is MSB, switch 1 is LSB). Address 0 is reserved for master-class devices; address 126 is the "no address" state used by the master to assign a new address; address 127 is broadcast and not usable for slaves.

Example DIP switch settings (ON = 1, OFF = 0):

The address is read only at power-on. If you change a DIP, cycle 24 V on the IM 153 or do an IM 153 power reset, or in HW Config right-click the slave → "PROFIBUS address…" → "Assign". The current address can also be assigned over the bus by the master (HW Config or SFC 12 "D_ACT_DP" + "Set_Address"), but only on IM 153-2/-2FO; the IM 153-1 always requires a manual DIP change.

For each PROFIBUS segment:

• Enable termination on the two physical end nodes only (terminate ON, pull-up/pull-down ON on the active terminator).
• Keep stub length under 1 m per slave at 1.5 Mbit/s; for 12 Mbit/s, the bus should be daisy-chained, not stubbed.
• Select the baud rate in HW Config (9.6 kbit/s to 12 Mbit/s) and verify the cable length budget against the Siemens PROFIBUS table: 1.5 Mbit/s ≈ 200 m, 12 Mbit/s ≈ 100 m, repeaters extend by another segment.
• Use PROFIBUS cable type "violet" (Siemens 6XV1830-0EH10 or successor 6XV1830-0EH20) with a defined shield bond at every cabinet entry.

PROFINET Device Naming and IP Assignment

PROFINET replaces the DIP switch with a station name. The IM 153-4 PN ships with a default name of the form et200m-[MAC-tail]. The CPU 317-2 PN/DP and every other IO controller must learn that name in order to address the device, so the first step after a hardware swap is a name assignment via the engineering tool.

1. Open TIA Portal → "Online & Diagnosis" → "Accessible nodes".
2. Right-click the IM 153-4 PN entry and select "Assign PROFINET device name".
3. Pick the device by matching the MAC address printed on the front (do not pick by visibility alone – two unconfigured devices on the same network can collide).
4. Enter the station name (e.g. et200m-line1-station03) and assign role "IO device".
5. Set the IP address, subnet mask, and (if a router is in use) router address. The PROFINET device name is the only mandatory assignment; the IP is derived from it during controller startup.

Conventions that prevent future confusion:

• Use a name that reflects topology: et200m-line1-station03 rather than io3.
• Stick to lowercase letters, digits, and dashes only (RFC 1123 style). Avoid underscores – some Profinet tools treat them inconsistently.
• Document the name + IP + MAC in the cabinet drawing. A label on the module is not enough; field humidity and solvents lift most stickers in a year.

Installing the GSD / GSDML File

The CPU's hardware catalog only lists modules that ship with the engineering tool. Remote devices must be loaded by a GSD (PROFIBUS) or GSDML (PROFINET) file that matches the IM 153 firmware. For the IM 153 family use the file family SIEM8115.GSD (IM 153-1/-2) or GSDML-Vx.x-Siemens-ET200M-IM153-xPN-YYYYMMDD.xml for PROFINET. The latest GSD/GSDML packages are bundled with STEP 7 / TIA Portal via the Hardware Support Package (HSP) and mirrored in the Siemens support portal at support.industry.siemens.com.

Installation paths:

• STEP 7 V5.x: Start → SIMATIC → STEP 7 → "Install GSD File…" → point to the .gsd / .gsdml directory → OK → restart HW Config.
• TIA Portal V16+: Options → Manage general station description files (GSD) → browse to the .xml → Install.
• TIA Portal via HSP: Options → Support Packages → Install HSP → pick "ET 200M IM 153-4 PN" → restart. HSPs are released with every TIA Portal service pack and include GSDMLs for current IM 153 firmware.

Configuring the Stations in STEP 7 V5.x (HW Config)

1. Open the S7 project → SIMATIC 300 Station → HW Config.
2. Insert the CPU 317-2 PN/DP from the catalog under SIMATIC 300 → CPU 300 → CPU 317-2 PN/DP → 6ES7317-2EK14-0AB0 → V3.3.
3. Place a PROFIBUS(1) subnet on the DP master interface; set the baud rate (default 1.5 Mbit/s, profile "DP").
4. From the catalog path "PROFIBUS DP → ET 200M" drag the IM 153 onto the PROFIBUS line. Enter the same PROFIBUS address that the DIP switch on the physical module shows.
5. Open the IM 153 station by double-clicking it. Slot 1 is occupied by the IM 153 itself. Drag each SM/AI/AO module from the right-hand catalog into slots 2..N exactly in the order the modules are physically installed.
6. For each slot double-click to set the I/Q address range, diagnostic address, and (for analog modules) the measurement type and channel grouping. Note the diagnostic address (e.g. 8192 for the IM 153) – this is the address reported in OB82, OB84, OB86.
7. Save and compile, then download the HW Config to the CPU.

For PROFINET, the equivalent step is performed in NetPro (PROFIBUS view) and in HW Config (PN view) – the IM 153-4 PN sits under "PROFINET IO → ET 200M" in the catalog and is dragged onto the PN subnet of the CPU. TIA Portal is the preferred tool for PROFINET-heavy installations because STEP 7 V5.x PROFINET support ended with V5.5 + SP8.

Configuring the Stations in TIA Portal (Devices & Networks)

1. Add a new device in the project tree, type "SIMATIC S7-300", order number 6ES7317-2EK14-0AB0.
2. Open "Devices & Networks" and switch the view to "Network view".
3. From the right-hand hardware catalog, expand "Distributed I/O → ET 200M" and drag the appropriate IM 153 (PROFIBUS or PROFINET variant) onto the bus line connected to the CPU.
4. Connect the IM 153 to the CPU's PROFIBUS interface or PROFINET interface; TIA Portal will prompt for a station name and IP if PROFINET is used.
5. Switch to "Device view" of the new IM 153 station. Slot 1 is the IM 153; drag SM/AI/AO modules into slots 2..N. The slot order in software must match the physical slot order – this is the single most common source of "remote I/O not working" tickets.
6. Compile and download to the CPU 317-2 PN/DP. Use "Online → Accessible nodes" to verify the IM 153 is reachable and has the correct diagnostic status.

TIA Portal also exposes the "Topology view" (Online → Topology) which is invaluable when commissioning multi-station installations, because it draws the physical cabling as it sees it from LLDP and highlights differences between configured and actual cabling. Always commission with a topology diagram – hand-drawn cable lists drift out of date within weeks of a panel rework.

Slot Mapping: Matching Software to Physical Hardware

The S7 cannot auto-detect the modules behind an IM 153 – it relies entirely on the order the modules are placed in the project. If physical slot 4 contains an SM 321 DI 32×DC24V but the project has an SM 322 DO 8×DC24V at slot 4, the CPU will not flag a configuration error at startup. Instead, the output module is wired where the input module is, and the program reads inputs from a module that is physically elsewhere. The fault is silent until a field device is wired and a sensor input does not behave as expected.

Procedure to verify slot mapping:

1. Power the IM 153 and observe the ACTIVE LED – if it is solid green, the IM 153 has completed parameterization and the CPU-supplied configuration matches the physically present module set.
2. In TIA Portal, right-click the IM 153 → "Online & Diagnosis" → "Module information" → the "Actual" column shows the module plugged at each slot. Compare to the "Configured" column.
3. In STEP 7 V5.x, use "PLC → Module Information" on the IM 153's diagnostic address and switch to the "Module" tab.
4. When commissioning multiple stations, write the slot number on each module with a permanent marker – 3 minutes of labelling saves hours of fault hunting.
5. Force table test – toggle one DI and one DO per station from the watch table to verify the I/Q address and wiring end-to-end.

Multiple ET 200M Stations: Topology and Bandwidth

The CPU 317-2 PN/DP supports up to 124 DP slaves and up to 256 PN IO devices; the practical limit is set by the cycle time budget and by the physical topology. Use the following rules when designing a multi-station network:

Best practice for a multi-station ET 200M installation on a CPU 317-2 PN/DP:

• Reserve PROFIBUS DP for legacy or safety stations; run new stations on PROFINET for higher throughput and simpler cabling.
• Use a managed PROFINET switch (SCALANCE XC208 / XC216 / XB208) between the CPU and more than four PN stations so that the CPU's 2-port switch is not overloaded and so that LLDP topology is supported.
• Group stations physically by their assigned PN subnet and assign non-overlapping IP ranges (e.g. 192.168.10.0/24 for line 1, 192.168.11.0/24 for line 2). Document the subnet and the gateway clearly.
• Always enable "Device replacement without exchangeable medium" (port-statistics-based) so a swapped IM 153-4 PN is recognised by the controller and gets its name reassigned automatically.
• Configure MRP (Media Redundancy Protocol) for ring topologies – every SCALANCE in the ring must be MRP-capable and at least one must be MRP Manager.
• Cycle-time budget rule of thumb: keep the sum of all station update times below 30 % of OB1 to leave headroom for non-cyclic services (PG online, HMI, web server).

Diagnostic LEDs and Error Codes

Each IM 153 carries a front panel with the standard SIMATIC diagnostic LEDs. Always start any field debugging here before opening TIA Portal.

The CPU reports ET 200M faults to specific OBs that the S7 program should implement:

• OB 82 – Diagnostic interrupt: fires when a module in the ET 200M station reports or clears a channel-level diagnostic (broken wire, overflow, underflow). Read SZL 0x0A2A (partial list extract) inside the OB to get the channel and the diagnostic event ID.
• OB 84 – Hardware interrupt (CPU fault): fires on a CPU-detected hardware interrupt; the local-temp OB84_HEADER points to the module base address that raised the interrupt.
• OB 86 – Rack failure: fires when the entire ET 200M station goes away (PROFIBUS cable cut, PN station lost) or returns. Read the OB86_HEADER in the local-temp area: bytes 8-9 contain the logical base address, byte 10 the event type (0x55 rack restored, 0xC4 rack failure, 0xC5 module slot failure, 0xC6 station return).
• OB 122 – I/O access error: fires when the program reads/writes a slot that has gone away. Treat as a watchdog to put outputs in a safe state and log the OB_LOCAL_VAR for diagnostics.

Commissioning Verification Checklist

Use this checklist on the first cold start of a multi-station ET 200M installation. Each item must be ticked before the line is handed over to operations.

1. All 24 V rails (PS 307, IM 153 sensor supply, AO/DO loads) measure 24.0 V ± 5 % under load.
2. DIP switch addresses (PROFIBUS) and PROFINET names + IPs match the cabinet drawing exactly.
3. PROFIBUS terminators ON only at the two end nodes of the segment; PROFINET port interlinks OFF at the device, ON at the managed switch uplinks if loop prevention is required.
4. Shield clamps in place and shield contact strips tight; shield bonded to cabinet PE at the entry, not at the module.
5. HW Config / TIA Portal "Go online" shows the IM 153 with status "OK" and every module with green module status.
6. Slot list under "Module information" matches the physical order; print it and file it in the cabinet.
7. Force table test – one DI and one DO per station toggled to verify the I/Q address and wiring end-to-end.
8. OB 82, OB 86, OB 122 downloaded and proven by deliberately removing one module and unplugging the bus connector.
9. CPU diagnostic buffer cleared and one warm restart executed to record a clean baseline.
10. Topology view (TIA Portal) compared against the as-built drawing; any LLDP port mismatch is investigated before sign-off.

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