Configuring PROFINET Stack Integration on Siemens IoT2000

Overview

The Siemens SIMATIC IoT2000 family — comprising the IoT2020 and IoT2040 gateways — bridges shop-floor PLC networks with higher-level IT/OT applications. Native support for the PROFINET industrial Ethernet protocol on these devices enables direct, deterministic exchange of process data with S7-1200, S7-1500, and ET 200SP controllers. This reference details the architecture, the C/C++ API integration path released by the vendor, the Node-RED compactcom-40-nodes wrapper for high-level languages, the Modbus TCP fallback, and the recovery interfaces required when SSH is lost during package installation.

PROFINET is defined in IEC 61158 and IEC 61784-2 and uses a layered stack that maps onto standard IEEE 802.3 Ethernet with real-time extensions (RT and IRT). Implementing the stack on an embedded Linux gateway requires both a real-time capable Ethernet MAC driver and a userspace protocol library that handles the PROFINET IO Device Finite State Machine, AR (Application Relationship) establishment, and cyclic data exchange.

Siemens IoT2000 Hardware Architecture

The IoT2020 and IoT2040 share the Arduino-format shield layout and an Intel Quark x1000 / x1020 SoC class architecture. The functional differences relevant to PROFINET integration are summarized below.

The second Ethernet port on the IoT2040 is the most relevant feature for PROFINET integration: it enables a physical separation between the PROFINET field network and the corporate IT network, allowing the gateway to terminate PROFINET frames on one port while publishing data to the cloud on the other.

PROFINET Protocol Stack Fundamentals

PROFINET follows the ISO/OSI model with two real-time classes:

• PROFINET RT (Real-Time) — cycle times from 1 ms, no special hardware required, uses standard Ethernet with VLAN priority tagging.
• PROFINET IRT (Isochronous Real-Time) — cycle times from 250 µs, requires hardware-accelerated switching (ERTEC) for cut-through and time-slot reservation.

For PROFINET IO Device implementation on a Linux gateway, the stack components are typically:

1. NDIS / Linux socket layer — raw Ethernet frame access via AF_PACKET or libpcap.
2. DCP (Discovery and Configuration Protocol) — handles station name assignment and IP configuration.
3. RPC / PN-DCP — device discovery and parameterization.
4. IO Device State Machine — handles AR establishment, data exchange, and watchdog.
5. Alarm handling — process, diagnostic, and upload-retrieval alarms.
6. GSD file — XML descriptor of the device's IO modules and slots.

The Siemens-proprietary C/C++ API released for the IoT2000 family targets Conformance Class A (CC-A) and CC-B devices. Conformance class capability must be declared in the GSDML file and verified with PROFINET certification tools from the PROFIBUS Nutzerorganisation (PI).

C/C++ API Integration Path

Siemens provides a C/C++ API for PROFINET on the IoT2000 series. The development workflow uses SWIG to generate bindings for higher-level languages, avoiding a per-language rewrite of the protocol state machine.

Typical directory layout after the SDK install:

/opt/siemens/profinet/
├── include/
│   ├── pn_device.h
│   ├── pn_alarm.h
│   └── pn_dcp.h
├── lib/
│   ├── libpn_device.so
│   └── libpn_rt.a
├── gsdml/
│   └── GSDML-V2.3-Siemens-IOT2000-YYYYMMDD.xml
└── samples/
    └── simple_io_device/
        ├── simple_io_device.c
        └── Makefile

A minimal PROFINET IO device loop skeleton in C:

#include "pn_device.h"
#include "pn_dcp.h"
#include 
#include 

static volatile int run = 1;
static void on_sig(int s){ (void)s; run = 0; }

int main(int argc, char **argv){
    signal(SIGINT, on_sig);

    pn_device_cfg_t cfg = {
        .station_name = "iot2000-1",
        .vendor_id    = 0x002A,        /* Siemens vendor ID */
        .device_id    = 0x0101,
        .max_ars      = 1,
        .interface    = "eth0",
    };

    if(pn_device_init(&cfg) != PN_OK){
        fprintf(stderr, "PN init failed\n");
        return 1;
    }
    pn_dcp_start();                  /* accept station name + IP */

    uint8_t inputs[64]  = {0};
    uint8_t outputs[64] = {0};

    while(run){
        pn_device_poll(1000);        /* 1 ms slot, RT cycle */
        if(pn_device_io_state() == PN_IO_RUN){
            pn_device_read_outputs(outputs, sizeof(outputs));
            /* user logic — fill inputs[] */
            inputs[0] = 0x01;        /* example: digital input word */
            pn_device_write_inputs(inputs, sizeof(inputs));
        }
    }
    pn_device_shutdown();
    return 0;
}

Compilation against the SDK:

gcc simple_io_device.c -o simple_io_device \
    -I/opt/siemens/profinet/include \
    -L/opt/siemens/profinet/lib -lpn_device -lpthread

SWIG Binding Generation for Education

To make the C API usable from C#, Java, and Python for educational deployments, generate SWIG wrappers:

// pn.i — SWIG interface
%module pn
%{
#include "pn_device.h"
%}

%include "cpointer.i"
%pointer_functions(int, intp);
int  pn_device_init(int device_id);
int  pn_device_poll(int timeout_ms);
int  pn_device_io_state();
int  pn_device_read_outputs(void *buf, int len);
int  pn_device_write_inputs(void *buf, int len);
int  pn_device_shutdown();

Generate wrappers for the target language:

swig -python -c++ pn.i        # Python
swig -csharp  -c++ pn.i        # C#
swig -java    -c++ pn.i        # Java
swig -tcl     pn.i             # optional Tcl/Tk teaching demos

Node-RED and compactcom-40-nodes Integration

For deployments that do not require PROFINET CC-B conformance certification, the Node-RED package compactcom-40-nodes installed via npm exposes industrial-protocol flows without writing C code. The package wraps HMS Anybus CompactCom 40 modules (PROFIBUS, PROFINET, EtherNet/IP, Modbus TCP, EtherCAT, CC-Link) into Node-RED nodes.

Install Node.js and the package:

root@iot2000:~# opkg update
root@iot2000:~# opkg install nodejs
root@iot2000:~# npm install compactcom-40-nodes
root@iot2000:~# systemctl restart node-red

A flow that polls a PROFINET IO slot and publishes the value to MQTT:

[{"id":"a1","type":"pn-input","z":"f1","name":"PN Slot 1",
  "device":"iot2020-1","slot":1,"byteOffset":0,"bitLength":16,
  "x":140,"y":120,"wires":[["b2"]]},
 {"id":"b2","type":"mqtt out","z":"f1","topic":"plant/iot2020/slot1",
  "qos":1,"retain":false,"broker":"m1","x":340,"y":120}]
]

The PROFINET field-side communication still requires the Anybus CompactCom 40 PROFINET module seated on the IoT2040's D-sub interface, which presents itself as an IO Device to the Siemens PLC. Node-RED here only handles the application-layer bridging, not the PROFINET real-time stack.

Modbus TCP Fallback Architecture

When PROFINET is not yet available on the gateway firmware or for non-Siemens controllers, Modbus TCP provides a viable alternative. The Node-RED modbus package installs cleanly on the IoT2000 series and has been observed running reliably with 100 ms poll cycles to S7-1500 holding registers.

root@iot2000:~# opkg install nodejs
root@iot2000:~# cd ~/.node-red
root@iot2000:~/.node-red# npm install node-red-contrib-modbus

Modbus TCP polling limits on the IoT2020's 256 MB RAM:

Hardware Connection Interfaces

TTL Serial under the Flip Lid

Both IoT2020 and IoT2040 expose a 3.3 V TTL UART beneath the small flip cover on the shield header. Pinout:

Default Linux device is /dev/ttyS0, 115200 baud, 8N1. With a USB-to-TTL adapter and minicom -D /dev/ttyUSB0 -b 115200 the user obtains a root console even when the Ethernet interface is misconfigured.

microUSB Device Port

The micro-USB port enumerates as a USB CDC ACM gadget only when the Yocto image was built with the iot2000-usb-gadget feature. If the host PC does not detect the CDC serial device, install the g_serial kernel module or reflash the gateway image.

Yocto Linux and opkg Package Management

The IoT2000 example image ships with the opkg package manager. Adding repositories and installing software:

root@iot2000:/etc/opkg# echo "src/gz all http://iotdk.intel.com/repos/3.5/iot2000/dynamic" >> /etc/opkg/iot2000-dynamic.conf
root@iot2000:/etc/opkg# opkg update
root@iot2000:/etc/opkg# opkg install nodejs

Educational Deployment Scenarios

The IoT2000 series is positioned for classroom and lab use because of its Arduino shield form factor and open Yocto build. Recommended teaching tiers:

Importing the gateway GSDML into TIA Portal V17 or later:

1. Open the TIA Portal project containing the S7-1200/1500 controller.
2. Options > Manage general station description files (GSD).
3. Browse to the gateway's GSDML XML file supplied by Siemens.
4. Drag the IoT2000 device from the catalog into the Devices & Networks view.
5. Connect the IoT2000 PROFINET port to the PLC PROFINET port; assign the device name matching the station_name in the C code.
6. Download the hardware configuration to the PLC and assign the device name from Online > Accessible devices.

PROFINET vs. PROFINET IRT Stack Footprint

The minimum binary footprint on the IoT2000:

IRT on the Quark SoC requires ERTEC-compatible cut-through switching, which the IoT2000 on-board switch does not provide. IRT is therefore not supported on this gateway family — only RT up to CC-B.

Troubleshooting Matrix

Standards and Conformance References

• IEC 61158 — Industrial communication networks — Fieldbus specifications.
• IEC 61784-2 — Additional profiles for ISO/IEC 8802-3 based communication networks (PROFINET profiles).
• PROFINET Installation Guide (PI, current edition) — cabling, grounding, and shielding requirements for CC-A/B networks.
• GSDML Specification V2.3 — XML schema for PROFINET device descriptors, distributed by PROFIBUS Nutzerorganisation.

Related Stack Alternatives

Outside the Siemens IoT2000 ecosystem, alternative PROFINET stacks are available for design comparisons and migration paths:

• PROFINET Stack Integration — ST partner Codewerk stack for STM32 microcontrollers, used in custom field devices.
• NXP PROFINET Protocol Stack — binary image for the i.MX RT1180 evaluation kit, intended as a reference port for high-performance MCUs.

Both stacks demonstrate that PROFINET IO Device implementations can be ported to constrained Cortex-M/A-class processors, but they do not change the IEC 61784-2 profile or the GSDML descriptor requirements.

Field Commissioning Procedure

1. Verify the gateway boots from SD card and obtains a console on TTL serial (/dev/ttyS0).
2. Configure eth0 with a static IP in the PLC PROFINET subnet (default S7 subnet: 192.168.0.0/16 range used by TIA Portal).
3. Start the PROFINET device binary: ./simple_io_device -n iot2000-1.
4. In TIA Portal, perform Online > Accessible devices; the gateway should appear with MAC and "no name assigned" status.
5. Assign the device name iot2000-1 from the TIA Portal dialog.
6. Download the configuration to the PLC and observe the PROFINET LED on the gateway turning solid green (AR established, IO RUN).
7. Force an output slot to a non-zero value from TIA Portal watch table; verify the value arrives in the gateway's logs at the configured cycle interval.

FAQ