Kärcher equips its gantry and self-service washing systems for cars and commercial vehicles with the Remote Diagnostics System 'RDS I' for remote control, remote queries and the transmission of service and fault messages. Among other things, this enables access to all codes stored in the fault memory of the PLC. These can be sent to one or more recipients as an SMS or as an e-mail via an SMS-to-email gateway. Service staff can also query the daily and total counter readings of the washing system at any time via SMS.

The integration of the IMON-G100 in 'RDS I' as a black box with hardware interfaces: The only thing that needs to be clearly defined is what data is generated, how it is processed and what data is to come out at the end and be transmitted securely.

© Insys icom

These specific requirements initially appeared to be problematic, as at first glance they could not be reconciled with the standard of current modems. For example, in the original design of the RDS with the GSM modem, which was discontinued in 2015, each of the two switching outputs could be used for ten different commands. For this purpose, the AT** commands from the incoming SMS messages in the modem were converted into ten different pulse sequences and output to the PLC.

In the end, however, a suitable solution was found with the GPRS router 'Imon-G100' from Insys icom. Designed as a fault indicator for monitoring and remote maintenance of small controllers such as the Siemens Logo!, the router has an RS232 interface as well as two digital inputs and outputs and can send freely configurable messages by e-mail, SMS or SNMP when definable events or times occur, even without a customer-specific programmed app. Unlike the previously used GSM modem, a LAN interface and security functions such as firewall and VPN are also included as standard. However, the decisive criterion for the Imon-G100 was the so-called 'sandbox', an integrated, programmable Linux environment.

Individual router functions via app

Code 'snippet' from the customer-specific app for handling the AT** commands that are sent from the PLC to the router via the serial interface.

© Alfred Kärcher

In principle, programs can be started, data can be collected and processed and services can be offered in the sandbox, just like on a Linux PC, without affecting or restricting the router functionality. The only condition is that the actions or programs do not require root rights. The sandbox has a fixed memory of 150 MB and up to 64 MB of RAM provided by the router's ARM9 system. Typical applications that can be executed directly on the router include protocol conversion, condition monitoring, visualization or data logging with a web server. The sandbox applications have access to the serial interface of the router, to the Ethernet of the LAN connection and to the respective device-specific WAN connection - in this case GPRS. Incoming SMS messages can also be forwarded to the app in the sandbox and interpreted. Kärcher uses precisely this function for remote retrieval of meter values and error memories.

With the app that Insys icom wrote for Imon use at Kärcher, all the functions of the previous GSM modem were implemented in the sandbox of the new mobile router:

• the interpretation of incoming service and alarm messages from the PLC in AT** format and conversion into message texts;
• Freely definable recipient groups for SMS and e-mail messages, the latter via SMS-to-email gateway;
• Interpretation of incoming SMS control commands and conversion into pulse sequences, which are output to the car wash PLC via the digital outputs of the Imon-G100;
• Detection of emergency stop activations and message dispatch;
• the reception of error codes from the PLC via the RS232 interface.

The new router not only provides Kärcher with a functionally identical solution, but also a solution whose range of functions can be adapted or expanded as required in the future by programming in the sandbox. The device's LAN interface also opens up the possibility of browser-based configuration of the router and app, eliminating the need for the separate configuration software that was previously required. The router can also be configured remotely via secure VPN networks. "We have thus created a future-oriented basis for further developments in order to be able to offer our customers additional added value in the coming years," summarizes Berger.

The routers used can use all cloud-based forms of remote monitoring and central visualization: The monitoring app available for this allows simple, efficient monitoring of the connected controllers and devices - as well as their own inputs.

Convenient monitoring via 'cloud control center'

Display of the functions that the app performs in the integrated Linux environment of the router.

© Insys icom

With a cloud account from Insys icom's Smart IoT platform or with the user's own cloud solutions connected via MQTT, the monitoring app can be used to transfer measured values, events and alarms for visualization and further processing or to use them in other specific infrastructures such as ERP systems.

Logical links in the monitoring app make it easy to combine elements to be monitored, desired actions, people involved or cloud services. Individual monitoring can also be linked in the app in the router to create escalating alerts. In the opposite direction, applications can be controlled directly from the cloud or via automatic actions from the router.

Users can also program more complex and application-specific apps themselves in C or C++. A free sandbox image is available to download online for this purpose. In addition to a demo video, there are various demo images with example functions that even beginners can use to quickly and easily create their own scripts and programs. More extensive programming and compiling of individual applications requires a Linux PC and the Software Development Kit (SDK) from Denx. In addition to C or C++, other programming languages such as Perl or Python can also be used.

Author:
Robert Torscht is an application engineer at Insys icom.

Edge computing on the router

While the sandbox was developed for devices with the Insys OS operating system, the latest routers in the MRO and MRX series run the icom SmartBox with icom OS firmware. Unlike its predecessor, the latter is based on Linux containers (LXC), in which different applications can run independently and completely separately from each other. Each application has its own IP and MAC address and can therefore be addressed directly - like a virtual device behind the router. As a result, the SmartBox differs significantly from the sandbox in terms of performance, flexibility and the number of applications running in parallel. Direct communication between the applications is also possible, so that they can be combined and - protected by the router's firewall - can exchange data securely. The communication parameters for each application can be configured directly via the icom OS or the command line. Encryption is also possible.

(Insys icom at the SPS IPC Drives: Hall 7, Stand 201)