## 5 Discussion
### Realtime Features  
A SICS control system uses IP networks for data transmission, regardless of the solution variation. From the perspective of an automation technician, these networks are a priori neither reliable nor deterministic, and are not within the jurisdiction of the respective technical automation solution. Extensive time measurements for different communication structures were, therefore, performed for both SICS prototypes [19].  
Figure 16: Technological structure of application example 2.  
A practice-oriented method was chosen for the time measurements, which allows direct statements about the reaction time of the described SICS controllers. Figure 17 shows the measurement setup for the examples.  
In the upper part of the measurement setup 1, an HTML page generates a pulse frequency with a JavaScript generator, which is sent to a PLC a digital signal. This digital output is connected by a short circuit bridge to a PLC input, which sends its value back to the HTML page. A time difference measurement is then carried and recorded in a histogram. This gives the reaction time \(\Delta\mathrm{T}_{\mathrm{R1}}\). Using this measurement method, the time characteristic of the process data transmission is obtained over a longer period of time and also detects the variance of the measurements over a probability curve.  
In the second measuring part 2, the short circuit bridge is opened at the PLC and the I/O signal is connected to an automation device (e.g., I/O module), which has a CPS interface and is controlled by a SICS controller. As a result, a histogram is displayed in the browser for the entire reaction time of the measurement setup  
\[\Delta\mathrm{T}=\Delta\mathrm{T}_{\mathrm{R1}}+\Delta\mathrm{T}_{\mathrm{R2}}.\]  
The response time of the SICS controller thus results in  
\[\Delta\mathrm{T}_{\mathrm{R2}}=\Delta\mathrm{T}-\Delta\mathrm{T}_{\mathrm{R1}}.\]  
Figure 18 shows the reaction time of the SICS controller.  
With respect to the real-time features, the following general statement can thus be made:  
With a SICS-SM or SICS-SMM solution, response times of about 80-100 ms at a 95% probability can be achieved by a usual Internet connection.  
If the SICS controller is operated only on the Intranet, response times of under 40 ms can be achieved.  
Figure 17: Measurement setup to determine the reaction time of a SICS controller.  
Figure 18: Determination of the reaction time of a SICS controller.  
Altogether, the statement can be made that technical processes with process times of \(>\)150 ms (simple assembly processes, temperature and mixing processes, climate and energy processes, etc.) can already be performed successfully from the cloud by means of a SICS.  
Compared to a classic PLC, it is currently not possible to guarantee 100% compliance with a specific time requirement for a SISC controller using IP networks and the cloud, but only with a certain probability. This must be taken into account in the respective application.  
The majority of the response time is caused by the run times in the network. The actual cycle time for the execution of the control program in the SISC runtime is less than 1 ms. Considering the use of new real-time networks, e.g., time sensitive networking (TSN), is expected to allow SISC controllers in the local or edge computing networks to control drive motors as well.