Resolving Siemens DP/PA Link GSD Errors in Omron CX-Profibus

1. Problem Overview

When integrating a Siemens DP/PA Link (6ES7 153-2BA01-0XA0 or 6ES7 152-2BA02) as a third-party gateway on an Omron CS1/CJ1 series PLC equipped with a CS1W-PRM21 or CJ1W-PRM21 PROFIBUS DP master, engineers commonly encounter a GSD file import failure in Omron CX-Profibus v1.x. The fault appears in two distinct ways:

• Omron's configuration tool rejects the GSD that has already been verified inside SIMATIC STEP 7 / PCS 7.
• The Siemens GSD Tool refuses to regenerate the IM153-2HF DPV1 H description (file IM153-2_HF_DPV1_H_12IO.zip), throwing a parsing or checksum error before any output is written.

The symptom leaves the engineer unable to drag the IM153-2HF into the PROFIBUS DP line of CX-Profibus, which prevents the entire PA segment from being commissioned. Because the same hardware works flawlessly when configured with SIMATIC software, the fault is not in the field wiring, the ET 200S, or the coupler — it is in the GSD-to-CX-Profibus translation pipeline.

2. DP/PA Link Architecture and Components

The DP/PA Link is the standard Siemens gateway that interconnects a high-speed PROFIBUS DP segment (up to 12 Mbit/s) with a lower-speed PROFIBUS PA segment (31.25 kbit/s, intrinsically safe). It performs a baud-rate decoupling and a protocol decoupling between the two physical layers. According to the PROFIBUS & PROFINET International product finder, the link physically consists of:

• One or two IM 153-2 interface modules mounted on a standard DIN rail (ET 200S backplane), acting as the DP-V1 slave side of the link.
• Between one and five DP/PA couplers (6ES7 157-0AC83-0XA0 for non-Ex, FDC 157-0AC83 variants for Ex) mounted to the right of the IM 153-2 modules.
• An optional DP/PA coupler redundancy configuration requiring the second IM 153-2 module.

The link is addressed on the DP side like any other DP slave — its own PROFIBUS address must be unique on the DP segment. The PA slaves hanging off each coupler are transparent to the DP master and appear as I/O slots behind the IM 153-2 module's slot architecture.

Two relevant hardware revisions exist on the IM 153-2 side that the engineer must distinguish:

When working with PCS 7 V7.0 SP1 or newer, only the 6ES7 152-2BA02 and 6ES7 153-2BA10 families are fully supported. For Omron, the 6ES7 153-2BA01-0XA0 (IM 153-2HF) is the most widely tested variant.

3. Identifying the IM 153-2HF Hardware

Before troubleshooting the GSD, confirm what is physically mounted in the panel. Read the label on the front of the module and verify the following three fields:

1. Order number (MLFB): 6ES7 153-2BA01-0XA0 versus -0XB0 (conformal coating) versus -2BA10. The trailing letter and revision number control which GSD is accepted.
2. Firmware version: printed on the side label, e.g. V6.0.4. CX-Profibus v1.x will refuse an IM 153-2HF GSD whose revision level is higher than what its device database has been pre-populated with.
3. PROFIBUS address: the rotary switches on the front of the module. The link is a slave — typical addresses are in the 1-7 range when no DP master diagnostics are required, or 3-12 when diagnostic repeaters are present.

If the device in the panel is a 6ES7 153-2BA00 (legacy IM 153-2, not HF), the GSD IM153-2_HF_DPV1_H_12IO.zip will not work and is, in fact, the wrong file. Use SIEM8150.GSD or the equivalent STEP 7 hardware catalog entry for the non-HF IM 153-2 instead.

4. Root Cause Analysis of GSD Import Failure

Three independent root causes have been observed in the field, in order of frequency:

Root Cause 1 — PCS 7 version mismatch with the GSD_Tool.
The Siemens GSD Tool for PROFIBUS and the IM153-2_HF_DPV1_H_12IO.zip archive contain a converter that re-writes the GSD to add slot-level H_12IO entries. The converter is hard-coded against the PCS 7 version installed alongside it. On PCS 7 V7.0 without SP, or on a stand-alone STEP 7 V5.4, the converter aborts with the dialog "Internal error: revision < X.Y.Z > not supported" or "No valid device description can be generated". The output ZIP is then empty or contains a stub file of 0 bytes.

Root Cause 2 — Archive integrity and CRLF/LF line endings.
When the GSD archive is extracted on a non-Windows workstation or transferred via FTP in ASCII mode, the GSD file (which is a plain text description in the IEC 61784 profile) gets its line endings altered. The Omron GSD importer parses the file strictly and will fail with "Syntax error at line 1" or silently truncate the file at the first 0x0A 0x0D pair. This frequently happens when the file is first downloaded on a Linux engineering laptop and then emailed to the controls team.

Root Cause 3 — Revision drift between STEP 7 hardware catalog and the IM 153-2HF firmware.
If the IM 153-2HF module has been firmware-upgraded in the field but the STEP 7 hardware catalog was never refreshed, the GSD generated by STEP 7 carries an older revision string. Omron's CX-Profibus v1.x compares the GSD revision against its internal device database version. A mismatch produces "Device IM153-2HF not in device database" even though the file parses cleanly.

5. Preparing the Siemens GSD File

The deliverable is a single, valid GSD file that CX-Profibus can ingest. The procedure is:

1. Install or upgrade STEP 7 / PCS 7 to a version that ships the hardware catalog containing the IM 153-2HF revision you have on the panel. Siemens' FAQ "How do you set up the DP/PA Link and how do you configure the DP/PA Link and DP/PA Coupler?" (Siemens Support entry 51678187) is the canonical reference for which PCS 7 version supports which IM 153-2 revision.
2. Open HW Config, drag the IM 153-2HF from the catalog onto a free DP-1 slot of a DP master system, accept the default slot 0, and then export the GSD by right-clicking the module and choosing Object Properties → GSD File → Export. This bypasses the GSD Tool and produces a single, complete file.
3. If the GSD Tool must be used (for example to generate the H_12IO variant), install the matching SIMATIC PCS 7 GSD Tool version. According to Siemens Support, PCS 7 V7.0 SP1 or later is required to generate the 6ES7 152-2BA02-based GSD. Earlier versions produce GSD files with truncated module lists.
4. Validate the file by re-importing it into STEP 7 on a second machine. If STEP 7 also rejects the file, the GSD is corrupt; do not pass it to CX-Profibus.

Hash the file (MD5 or SHA-1) and record it in the project documentation. The same hash should be reproducible on any engineering station that regenerates the GSD from the same hardware catalog revision.

6. Installing the GSD in Omron CX-Profibus

CX-Profibus v1.x is the configuration tool for the CS1W-PRM21 and CJ1W-PRM21 PROFIBUS DP master modules. The master module manual is published by Omron as document W409 — CS/CJ-series CS1W-PRM21/CJ1W-PRM21 PROFIBUS DP Master Operation Manual. The companion software manual CX-Profibus v1.x Operation Manual (W05E-EN-02) contains the GSD import procedure.

Recommended import sequence:

1. Launch CX-Profibus as administrator. The installer registers a per-user device database; an unprivileged first launch can write the import to a sandbox path that the configuration tool will not see on the next run.
2. Open the master configuration for the PRM21 module. From the menu bar, choose Configuration → Master → Import GSD. The dialog expects either an unpacked .GSD file or a ZIP archive that contains the GSD plus its bitmap directory.
3. When CX-Profibus prompts for device class, choose DP-V1 slave. The IM 153-2HF announces itself as a modular DPV1 slave with up to 12 I/O slots, and a wrong class selection will lock the slot configuration dialog.
4. After import, refresh the device catalog. The IM 153-2HF appears in the catalog tree at PROFIBUS DP → Additional Field Devices → IM 153-2HF.
5. Drag the device onto the PROFIBUS line. Assign the PROFIBUS address that matches the rotary switch on the front of the module (1-125, default 3).

For PA slaves that will hang off the IM 153-2HF, configure them as coupler slots rather than DP slaves. CX-Profibus exposes this with a right-click on the IM 153-2HF → Insert PA Device. The PA segment baud rate is forced to 31.25 kbit/s and cannot be overridden.

7. Configuring the CS1W-PRM21 / CJ1W-PRM21 Master

The Omron PROFIBUS DP master is the CS1W-PRM21 for CS1 series PLCs and CJ1W-PRM21 for CJ1 series PLCs. Both modules occupy one slot on the CPU rack (CS1) or expansion rack (CJ1) and are configured as special I/O units. The module is a full PROFIBUS DPV0/DPV1 master and supports up to 125 slaves at 12 Mbit/s.

Key parameters in CX-Profibus v1.x that must be set before the IM 153-2HF will communicate:

After the parameters are written, CX-Profibus generates two artefacts that must be downloaded to the PRM21 module: a binary configuration block (.P2M) and a parameterization block (.P2S). These are pushed to the module through CX-Integrator's I/O Table operation or, on older systems, via the PRM21's serial configuration port.

8. Network Topology and Commissioning

A typical hybrid segment looks like this:

+-------------------+    12 Mbit/s    +-----------------+    31.25 kbit/s    +---------------+
|  CJ1W-PRM21       |================|  IM 153-2HF     | ~~~~~~~~~~~~~~~~  |  PA Slave 1   |
|  (PROFIBUS master)|                |  (DP/PA Link)   |  ~~~~~~~~~~~~~~~~  +---------------+
|  Slot 0, addr 0   |                |  DP addr = 3    |  ~~~~~~~~~~~~~~~~  +---------------+
+-------------------+                +-----------------+  ~~~~~~~~~~~~~~~~  |  PA Slave 2   |
                                     |  DP/PA Coupler 1|                    +---------------+
                                     +-----------------+  ~~~~~~~~~~~~~~~~  +---------------+
                                                                          |  PA Slave 3   |
                                                                          +---------------+

Commissioning sequence:

1. Power up the CJ1W-PRM21 with all DP slaves disconnected. Confirm the PRM21's RDY LED is solid green and the ERR LED is off.
2. Connect the IM 153-2HF only. Confirm DP link is established (the SF and BF LEDs on the IM 153-2HF are off when communication is healthy).
3. Walk through the PRM21's diagnostic screen. The IM 153-2HF should appear with the configured PROFIBUS address and a green status.
4. Hot-attach the first PA coupler. Confirm that the PA segment powers up (typically 24 V DC fieldbus supply through a coupler DP/PA power conditioner).
5. Hot-attach the PA slaves one at a time. Verify that each appears in the coupler slot map of the IM 153-2HF.

9. Verification and Diagnostic Steps

After the link is online, run these checks in order:

1. From CX-Profibus, request the Live List. The IM 153-2HF must appear with its configured address and no diagnostic flag.
2. Read the IM 153-2HF's slave diagnostic buffer (CX-Profibus → right-click slave → Slave Diagnostics). It must return at least 6 bytes of standard DP diagnostic data plus a slot-level diagnostic for the active PA coupler.
3. Read back the process image of a known PA device, e.g. a pressure transmitter. The value must match the value reported by a hand-held calibrator on the same loop.
4. Force a link-down event by removing a PA slave's segment terminator. The IM 153-2HF must report a slot-level diagnostic to the PRM21 within one bus cycle (≤ 1 s at 1.5 Mbit/s).
5. Capture a PROFIBUS trace with a class-2 master tool such as PROFIBUS Diagnostic Repeater (Siemens 6GK1 510-2AA10) or an Amprolyzer. Verify that the master's output data length matches the sum of the configured PA slaves' cyclic I/O sizes.

10. Troubleshooting Matrix

11. Practical Field Notes

Several field-proven tips reduce commissioning time on hybrid Siemens/Omron PROFIBUS networks:

• Always store the GSD, the bitmap directory, and the PRM21 firmware version in the same project folder. When an upgrade happens on one component, the GSD and the CX-Profibus configuration must be revalidated together.
• When the PA segment contains more than eight PA slaves, prefer the redundant 2x IM 153-2 link (two IM 153-2BA01 modules on the same rail) — this prevents the PA segment from being a single point of failure on critical processes.
• The PRM21 supports a maximum of 512 bytes of input and 512 bytes of output per slave. The IM 153-2HF modular layout must therefore fit in this envelope; an over-sized GSD will be rejected at parameterization time.
• If PCS 7 is not available on the engineering site, install a stand-alone STEP 7 V5.5 SP4 with HF1 (or later) — the hardware catalog in that release contains the IM 153-2HF revision 7 GSD and is sufficient to generate a valid file for CX-Profibus.
• For Omron support escalation, have the PRM21's serial number, firmware version, CX-Profibus v1.x build number, and the GSD's revision string ready. Omron support typically does not need the GSD file itself — they will cross-check the revision string against their device database.

12. Related Standards and References

The following international standards govern the components used in a hybrid Siemens/Omron PROFIBUS network. The values cited in the standards are normative, but the actual permitted values in any given product are the manufacturer's published limits.

• IEC 61784-1 — Industrial communication networks — Profiles (defines PROFIBUS DP and PROFIBUS PA profiles).
• IEC 61158-2 — Digital data communications for measurement and control — Fieldbus for use in industrial control systems — Part 2: Physical layer specification and service definition (defines 31.25 kbit/s MAU used by PA).
• IEC 61158-3 / -4 / -5 / -6 — Data-link and application layer for PROFIBUS DP/PA.
• EN 50170 / EN 50170-2 — European adoption of the PROFIBUS standard.
• FISCO model (IEC 60079-11) — applies to intrinsically safe PA segments.

Always verify the standard revision that is legally applicable in your jurisdiction; do not assume the values in the article supersede a national deviation.