IM-184 PROFIBUS DP Slave Module: GSD Configuration and Integration

The Siemens IM-184 is a PROFIBUS DP slave development module that has been in service since the late 1990s as part of the SIMATIC ecosystem. Built around the LSPM2 (Lean Siemens PROFIBUS Master) protocol ASIC, the IM-184 is shipped to OEMs and developers who need to design their own PROFIBUS DP slave devices without licensing a full protocol stack. Because the module is configured entirely by hardware jumpers and ships without a vendor-specific GSD file, integrators must build a device description that matches their chosen I/O mapping before the slave is recognized by a DP master. This reference covers the hardware, the LSPM2 jumper matrix, GSD construction, and integration into STEP 7 / TIA Portal.

1. IM-184 Module Identification and Variants

The IM-184 is a development board, not a catalog I/O module. It is intended for engineers who are prototyping a custom PROFIBUS DP slave and need a working reference design based on the LSPM2 ASIC. The following identifiers apply:

For a definitive device description file, always verify the part number with the SIMATIC catalog or with the Siemens Industry Online Support portal before ordering.

2. Hardware Architecture: LSPM2 ASIC Foundation

The IM-184 is a printed-circuit evaluation board that exposes the LSPM2 protocol controller together with a microcontroller interface, an RS-485 PROFIBUS transceiver, and 32 bits of parallel I/O. The LSPM2 implements the PROFIBUS DP layer-2 state machine in hardware, offloading the host microcontroller from real-time protocol handling. The host is responsible only for cyclic data exchange buffers, parameterization checks, and I/O updates.

2.1 Functional blocks

• RS-485 transceiver: Isolated PROFIBUS segment interface, 9.6 kbit/s to 12 Mbit/s, switchable termination.
• LSPM2 ASIC: Handles FDL (Fieldbus Data Link) layer, token-free slave operation, and SAP handling.
• Host interface: Parallel bus to the user's microcontroller, with shared memory for input and output process images.
• I/O port: 32 digital lines, organized as four 8-bit groups (Port 0, Port 1, Port 2, Port 3).

2.2 Why the IM-184 is developer-oriented

Because the LSPM2 is hard-wired for slave operation, the IM-184 cannot act as a DP master or as a DP-V1/V2 slave with diagnostic interrupts. The user accepts these constraints in exchange for a transparent, low-cost path to a working DP slave on a custom PCB. Siemens positions the module as a reference design rather than a catalog product, and the manual explicitly directs users to write their own GSD file rather than ship one with the board.

3. PROFIBUS DP Development Kit #4 (6ES7 195-3BA00-0YA0)

The IM-184 is not sold as a stand-alone catalog product for production use; it ships as part of PROFIBUS DP Development-Kit #4, which bundles the hardware, firmware example, and the 16-page manual. The kit was historically distributed by Siemens AG, Department ComDeC, in Fürth, Germany, and by the PROFIBUS Interface Center in Johnson City, Tennessee. The kit also includes example host firmware for common microcontrollers, schematics for the IM-184, and the jumper-configuration table reproduced in Section 4.

Current Siemens support for legacy DP development kits is handled through Siemens Industry Online Support. New development targeting PROFIBUS DP or PROFINET should use the current PROFINET IO Development Kit or the PROFIBUS DP-V1 Starter Kit; the IM-184 is documented here primarily for maintenance of installed systems.

4. Jumper Configuration Matrix

Configuration of the IM-184 is performed exclusively by on-board jumpers. There is no parameterization interface. The user must set jumpers to define:

1. The PROFIBUS slave address (0 to 125, set in binary with seven jumpers).
2. The direction of each 8-bit I/O port (input or output).
3. The baud rate (auto-detect, no jumper, or forced baud rate for legacy masters).

4.1 I/O direction combinations

The 32 I/O lines are split into four 8-bit groups. The direction of each group is independent, giving the configurations summarized below. The user's GSD file must match the jumper settings exactly; otherwise the DP master will declare a configuration fault.

Word and double-word consistency is not guaranteed by the LSPM2 in all operating conditions. If the user requires consistent 16-bit or 32-bit process data, the host application must buffer and re-order bytes. The GSD file must list the I/O length in bytes, never in bits, to avoid misinterpretation by STEP 7.

4.2 Slave address setting

The seven station address jumpers follow the standard PROFIBUS convention: jumper open = 0, jumper closed = 1, weighted 1-2-4-8-16-32-64 from LSB to MSB. Address 126 is reserved for commissioning devices, and address 127 is broadcast; both must not be assigned to a production IM-184. The changed address is recognized only on power-up, not during operation.

5. GSD File Structure and Specification

The Generic Station Description (GSD) file is a plain-text, keyword-driven description of a PROFIBUS slave. The IM-184 is not provided with a vendor GSD; the user must produce one. The structure follows the GSD Specification published by PI (PROFIBUS & PROFINET International), currently at GSD Revision 5.

5.1 File header and identification

Every GSD begins with vendor identification and product family declarations. A minimal valid header for an IM-184-based device is:

#Profibus_DP
GSD_Revision = 2
Vendor_Name = "OEM Company"
Model_Name = "IM184-Slave"
Revision = "1.00"
Ident_Number = 0x0C0C
Protocol_Ident = 0
Station_Type = 0
FMS_supp = 0
Hardware_Release = "1.0"
Software_Release = "1.0"

5.2 Module and slot definitions

The IM-184 is treated as a modular slave with one DP identity (Ident_Number) but multiple possible slot configurations. Each user-defined module describes one combination of inputs and outputs. A configuration that provides 2 bytes IN and 2 bytes OUT is declared as:

Module = "16DI / 16DO mixed" 0x10, 0x21
EndModule

Where 0x10 declares 2 bytes of input (hex 0x10 = 16 bits) and 0x21 declares 2 bytes of output (hex 0x21 = 16 bits + output bit). The full set of module identifiers is defined in the GSD specification, and any module order that the user intends to support must be added to the GSD.

5.3 Supported baud rates

The IM-184, like all DP-V0 slaves, advertises the baud rates it can detect. The default declaration is:

9.6_supp = 1
19.2_supp = 1
45.45_supp = 1
93.75_supp = 1
187.5_supp = 1
500_supp = 1
1.5M_supp = 1
3M_supp = 1
6M_supp = 1
12M_supp = 1

5.4 Diagnostic and user parameters

The IM-184 supports the standard DP-V0 diagnostic frame (6-byte station diagnostic) but not DP-V1 alarms. If the user needs extended diagnostics, the LSPM2 must be queried through the host interface and the standard 6-byte frame stuffed with the user-defined identifier 0x0A and the corresponding status bytes.

6. Building the GSD with GSDEdit.exe and GSDcheck.exe

The two utilities historically shipped with the kit are GSDEdit.exe (graphical GSD editor) and GSDcheck.exe (validator). The validator is the more important of the two: a syntactically invalid GSD will be silently rejected by STEP 7 or TIA Portal, often with the unhelpful message "The GSD file is inconsistent". The workflow is:

1. Edit the GSD in any text editor (GSDEdit.exe is optional but helps with the keyword table).
2. Run GSDcheck.exe IM184slave.GSD and resolve every warning it reports.
3. Confirm that the file encoding is Windows ANSI (CP1252); UTF-8 BOM is acceptable, but UTF-8 without BOM will fail older STEP 7 versions.
4. Confirm line endings are CRLF; LF-only line endings are rejected by some Siemens tools.

7. Integrating the IM-184 in STEP 7 / TIA Portal

7.1 STEP 7 V5.x procedure

1. Open HW Config and select the PROFIBUS DP master (for example, a CPU 315-2 DP).
2. Choose Options > Install GSD File and browse to the validated IM184slave.GSD.
3. Insert the device from the catalog under the assigned vendor and PROFIBUS DP path.
4. Drag the desired module (matching the jumper setting) into slot 1 of the slave.
5. Set the PROFIBUS address in HW Config to match the address set by the IM-184 jumpers. The HW Config value and the hardware value must agree exactly.
6. Compile and download the hardware configuration.

7.2 TIA Portal procedure

1. Open the device view and select the DP master.
2. Right-click PROFIBUS DP > Master system and choose Add device > Other field devices > PROFIBUS DP.
3. Browse to the GSD and import. The IM-184 will appear in the catalog under the vendor name declared in the GSD.
4. Place the slave, assign the address, and choose the module that matches the physical jumper setting.
5. Use the device's I/O addresses (for example, IB 0..1 for inputs 0/1 and QB 0..1 for outputs 0/1) in the user program.

8. PROFIBUS DP Address and Bus Parameters

The bus parameters of an IM-184 segment are inherited from the master. The standard DP cycle time for a 12 Mbaud segment with 32 slaves is approximately 1 ms, and the IM-184 contributes roughly 50 µs of processing latency per telegram at that baud rate. The following table summarizes the timing budget:

The IM-184 does not impose a minimum slot time. The host must, however, complete its read/write of the LSPM2 dual-port RAM within one DP cycle to avoid DXB (Data Exchange Broadcast) overruns when the slave is operated behind a Y-link or a DP/PA coupler.

9. Diagnostic Indicators and Troubleshooting

The IM-184 has three on-board LEDs. Their meanings, drawn from the LSPM2 reference firmware shipped with the kit, are summarized below.

9.1 Troubleshooting matrix

For intermittent dropouts similar to those reported on the SIMATIC HMI/PLC boundary, also verify that the DP master's slot time is at least 6 bit times longer than the worst-case IM-184 response, and that the bus is not exceeding the maximum 32-station repeater-segment count (counted on a DP-V0 segment, the limit is 32 per segment, 126 with up to 3 repeaters).

10. Standards Reference: IEC 61158 / EN 50170

The IM-184 implements PROFIBUS DP-V0 as defined in the following standards. The user is responsible for verifying compliance of the final product against the current revision of the applicable standard.

For the GSD specification itself, refer to the PI (PROFIBUS & PROFINET International) document GSD Specification, Revision 5, which supersedes the older Revision 2 used in legacy kits.

11. Replacement and Migration Path

For new designs, the IM-184 has been superseded by:

• SPC3 / SPC4 / SPC56 ASIC family for PROFIBUS DP slaves (Siemens).
• PROFINET IO Development Kit for Ethernet-based designs.
• netX / comX protocol-on-module designs from Hilscher, which implement PROFIBUS DP slave as a loadable firmware.

Migration from a legacy IM-184 design to a modern PROFIBUS DP slave ASIC requires re-validation of the GSD (different Ident_Number) and a slot-layout review, but the DP-V0 bus protocol is unchanged. Existing STEP 7 / TIA Portal configurations can usually be migrated by replacing the device reference in the catalog.

12. Field Commissioning Checklist

1. Verify 24 V supply and 5 V regulator output with a multimeter before power-up.
2. Set the seven address jumpers; cross-check the address in the kit manual.
3. Set the four direction jumpers per the chosen I/O split.
4. Connect the PROFIBUS cable with A on green, B on red, shield bonded to the cabinet ground at the entry point only.
5. Power up the segment and confirm the POWER LED is on.
6. Open HW Config / TIA Portal, install the GSD, and place the slave at the configured address.
7. Download the configuration and verify the BUS LED transitions from flashing to steady on within 5 seconds.
8. Force a test output and read back a test input to validate process-data round-trip.
9. Archive the validated GSD, the kit manual, and the jumper-setting table in the project documentation folder.

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