DE102006034681A1 - Automation system`s cycle time stabilizing method for e.g. nuclear plant, involves forming cyclic process such that additional process is shifted when cyclic process does not disturb cycle start before starting cycle start - Google Patents

Abstract

The method involves releasing starting of a cyclic process (P) by an interrupt, and accessing an additional process e.g. control process, in identical system resources (13). The interrupt is caused by a time signal periodically emitted by a system time transmitter. The cyclic process is formed in such a manner that the additional process is shifted when the cyclic process does not disturb the cycle start before starting the cycle start while the cycle start with the time signal takes place.

Description

The The invention relates to a method for stabilizing the Cycle time of a cyclic process in an automation system as well as an automation system.

One Automation system controls and regulates one or more industrial Processes of an industrial plant. A controlling task is always behind a predetermined scheme executed. A regulatory task, however, detects an operating condition of the Industrial plant and affects this operating condition targeted.

The Detection of an operating state via sensors connected to the industrial plant are arranged. Which also includes for example, measuring physical quantities such as pressure or temperature. The influencing of an operating state is done via actuators. Actuators are, for example, solenoid valves or electric motors.

The Automation system is also set up so that it critical operating condition that may occur during operation of the system results, counteracts. Such a critical operating condition can cause injury or destruction lead the plant, but also a danger the environment. This counteraction can be regulatory or be in a controlled shutdown of the industrial plant. This will damage for the Industrial plant and / or the environment avoided.

One Automation system comprises at least one processor, an operating system, Memory for Data, and other system resources.

The Automation system allows execution of programs, by means of which the operating state of the industrial plant change leaves. One Program is a defined sequence of the automation system, with the help of which a specific destination can be reached, for example the change the operating state of an actuator.

When Process is called the expiration of a program. The processor of the automation system is generally a processing unit for processes. It regulates access of the individual processes to the system resources. Furthermore he assigns the individual processes of computing time and data memory over Process management system too. In this process management system point the processes graduated priorities and are therefore executed with a different preference. Of the In the present case, the term process generally also includes so-called tasks or threads.

system resources are system elements that from a process to its error-free execution needed become. These are the sensors integrated in the industrial plant and actuators, but also communication elements for influencing the actuators, or a memory for Dates.

Also the access of individual processes to the system resources is by means of of the process management system. Here are to avoid used by conflicts semaphores. Semaphores are program elements, the access to their assigned system resource only one or a limited Allow number of processes.

Around to achieve a defined operating state and its maintenance to ensure, run in the processor from various processes. The course of many these processes are cyclic, i. the processes are in one for each Process predetermined time interval, one cycle time, repeated. For example, cyclic processes are processes that are periodic make one or more measurements of physical quantities, but also processes, periodically polling the operating status of the industrial plant and influence.

Become now the measured values for regulation measured by a measuring process predetermined operating conditions used, fluctuations in the cycle time of the measurements especially noticeable with very short cycle times. If a regulation process intrinsically difficult to control and / or it is a measurement safety-critical measured variables, is damage and / or destruction at least parts of the industrial plant with unpredictable consequences for the Environment possible.

A Influencing the cycle time of measurements takes place in particular when system resources are blocked by other processes and for the measurement process not available stand. Thereby can the distances between the individual measurements, resulting in particular at a very high measuring cycle a not negligible Measurement error results.

Cyclic processes in the automation system are usually caused by so-called cyclic interrupts. By interrupt is generally understood a short-term interruption of a first process to execute a second process. With the help of an interrupt, therefore, the processing of a pending cyclic process is initiated and usually another process is interrupted at the same time. The cyclic interrupts themselves are triggered by a clock or system timer. The system timer gives a high accuracy it and periodic time signal (tact time). In today's automation systems, this time signal has a period of a few milliseconds, in particular of 1 ms. In addition to the cyclic interrupts and interrupts for event signaling can be provided, for example, so-called communication interrupts that are not triggered by the clock.

With Help of the time signal is usually a sufficiently accurate start of the measuring cycle and thus a sufficiently high accuracy of the cycle time it can be reached if the cycle is started with the time signal. However, there are some factors that cause it the interrupt or the actual beginning of the cycle is not in time defined manner offset from the time signal occurs. This results Cycle time fluctuations that can lead to incorrect measurement results. One such factor is, for example, a so-called interrupt lock, which use some processes. The interrupts lock serves to ensure that the particular process does some of its job, especially not interruptible tasks, can still finish defined before going through the interrupt is interrupted. Another factor is in the Use of semaphores to see. Is the semaphore by a occupied by another process, the measuring process must start with its cycle first wait for the semaphore to be released again. The waiting time on the semaphore z. B. be up to 1 ms. The interrupts lock For example, it can be up to 0.5 ms.

such Cycle time fluctuations lead to highly sensitive measurements too undesirable high measurement errors. An example of this is the neutron flux measurement in a nuclear reactor. Here, the neutron flux is through high-precision measuring instruments continuously recorded. Through the cyclical measuring process becomes common the "meter reading" between two consecutive following read-outs recorded and related to a time difference. Can the time difference can not be measured exactly, then the reference cycle time (nominal Cycle time). Varies the time interval between two Readouts, i.e. If it deviates from the nominal cycle time, this leads to wrong measurement results.

So far There was a possibility to reduce the measurement error due to cycle time shifts in periodically recurring measurement processes therein, processes that the Cycle time of critical measuring processes influence, not at all or only with a low priority, that is, depending on the utilization of the Processor may be strong slowed down to expire. This procedure was particularly relevant Cyclical checks on functionality of the automation system. In this way, elements of the Automation system either not at all or in a very rough Time grid on their functionality checked out. This elevated the risk of disturbances the entire automation system or parts thereof. Especially in very safety-critical technologies, such as of nuclear technology, it is therefore desirable, all Components of the automation system in one possible check tight time grid, at the same time but measuring operations, the for the regulation of the industrial plant and thus for the controllability of the industrial process are relevant to perform as precisely as possible.

Of the Invention is based on the object, a constant cycle time for one Process, especially for to ensure a safety-relevant process.

The Task is according to the invention solved by a method for stabilizing the cycle time according to claim 1. In addition to the cyclical process running in the automation system At least one more process based on identical system resources how the cyclic process accesses. The cyclical process is going through triggered an interrupt, which again by a periodically issued by a system timer Time signal is initiated. For cycle time stabilization is the cyclic process in this case designed such that before the beginning of the Cycle start the further process into a cycle start not disturbing State is offset and the beginning of the cycle simultaneously with a Time signal takes place.

This Design is based on the consideration, that the time signal for one possible constant and accurate cycle time determination is sufficient and thus is suitable as the start time of each cycle start. The Cycle time is determined in a simple manner by counting the individual time signals. To ensure that the time signal coincides with the beginning of the cycle is, the cyclical process ensures that at the time known to him the other processes do not disturb the beginning of the cycle, ie they do not delay the time.

The beginning of the cycle is understood to mean the point in time at which the actual time-critical sub-process takes place, in particular the start of a measurement signal read-out. The start of the cycle does not necessarily coincide exactly with the start of the process cycle. It is crucial that the beginning of the cycle is exactly coupled with a time signal and that therefore the cycle time is exactly definable. Compared to the previous procedure, in which the beginning of the cycle was only loosely coupled with the start of the process cycle and thus with the interrupt triggering the process, it becomes This achieves a significantly higher accuracy of the cycle time. Because due to the use of semaphores or interrupts, for example, time shifts between the time signal and the actual beginning of the beginning of the cycle can occur, so that the cycle time varies.

According to one appropriate training is provided that after the start the process first a synchronization sequence is executed while the other processes be put in a state not disturbing the beginning of the cycle. Only then is at a subsequent time signal and thus a subsequent Interrupt the beginning of the cycle made. In this embodiment becomes aware of the beginning of the cycle, with the time-critical sub-process is started, from the actual start of the cyclic process decoupled and it is called a synchronization sequence here Routine preceded by that that particular ensures the next Time signal of the beginning of the cycle take place simultaneously with the time signal can.

According to one expedient embodiment, the further process works with a Interrupt lock and while the synchronization sequence will initially be a synchronization between the Time signal and the interrupt made. This is done after a first interrupt, which starts the cyclic process, a stop call for the rest Process causes, so that at the next time signal the interrupts is not effective. The further process is particular a monitoring process, with the functionality constantly monitored by the automation system becomes. Such a monitoring process usually runs in the background and preferably in an infinite loop. The cycle and thus the cycle time are determined by the Processing time of a loop pass and is for example a few minutes to hours.

By the delivery of a stop or inhibit signal is therefore ensured that the next one Interrupt not delayed due to an interrupts lock Time signal takes place. The beginning of the cycle can therefore start with the next interrupt take place, since this takes place simultaneously with the time signal.

Conveniently, the start of a respective process takes place in the event of an interrupt based on priorities, in each case the process with the highest priority is started if this process is pending. Preferably the time-critical cyclic process has the highest priority. At a Interrupt therefore automatically - after the interrupts have elapsed - the cyclic Process and thus the synchronization sequence started. To the Start cycle start at the same time as the next time signal to be able to It is necessary that the cyclic process is in a wait state until to the next Interrupt goes over. To prevent that during this waiting state of the monitoring process starts again and possibly an interrupts lock takes effect, the stop or inhibit command is issued. It is essential, therefore, that the cyclical process (monitoring process) locked at the time of one or the following (timer) interrupts is, with which the time-critical process is started, and that the lock afterwards is canceled again.

According to one expedient development is provided here that the lock the monitoring process is canceled by a start command, the start command preferably at a fixed time immediately after the beginning of the cycle initiating interrupt occurs. Following the lock can the monitoring process be resumed as soon as no parent processes anymore are active. By this measure becomes the lock of the monitoring process on the shortest potential Limited period, around the available to be able to optimally utilize the outstanding processor processing time. in this connection In particular, it is assumed that the interrupts of the further process (more precisely: the sum of the interrupts, the duration of the lock call and a PAUSE call) is shorter than the time interval between two consecutive time signals, that is with the next time signal the beginning of the cycle can take place, and that after the beginning of the cycle preferably quickly releasing the monitoring process can be done. Once the cyclic process has its individual work steps The monitoring process can therefore resume if no higher-priority processes are to be processed queue.

Preferably is still a semaphore provided, which provides access to the System resources of the cyclic process and another process regulates, wherein the cyclic process is designed such that he occupies the semaphore before the beginning of the cycle.

In this case, the further process is, in particular, an operating process which is triggered by an automatic or manual (indirect) operator request of the automation system or by operating personnel of the automation system. Such operating prompts are, for example, automated control commands for the installation, the setting of variables or also the interrogation of variables and states, in particular in the context of a diagnosis. Such Bedienaufforderungen can also be triggered manually by the operator indirectly. By the assignment of the semaphore right early before the beginning of the cycle, it is ensured that the beginning of the cycle can actually take place with the interrupt correlated with the time signal, and that it is not necessary to wait for release by the semaphore. The assignment of the semaphore takes place in particular during the synchronization sequence. For this purpose, a corresponding call to the semaphore is started and waited until the semaphore is released. As soon as the semaphore is released, the cyclic process occupies the semaphore so that the semaphore does not have to wait for the subsequent interrupt. In order to ensure a synchronization between the subsequent time signal and the beginning of the cycle, after the semaphore has been assigned to the cyclic process, the cyclic process is put into a waiting state until the subsequent interrupt triggers the beginning of the cycle. It is first occupied the semaphore and then waiting for the next interrupt.

at Systems in which at the same time an interrupt lock by a low-priority process, in particular monitoring process, and a Assignment of the semaphore is possible through an operating process, is preferably provided that initially a synchronization between the time signal and the interrupt is made by - as already executed - after one first interrupt a blocking command for the monitoring process becomes. Only with the following interrupt then a signal for the assignment of the semaphore with the cyclic process.

Either the operating process as well as the monitoring process generally form processes that share common data areas read and / or write to the cyclic process. by virtue of the common data areas (shared resources) need these other processes each with the cyclic process via suitable Synchronization means, such as the described semaphore or by other synchronization means such as so-called Critical Sections be coordinated. Due to access to common data areas simultaneous accesses are excluded and waiting times result, which are disadvantageous in the present case. By the procedures described here with semaphore and / or interrupt lock will have the negative impact canceled on the constancy of the cycle time.

According to one preferred alternative becomes both a blocking command for the monitoring process as well as a call to the semaphore to prove this. Due to this almost simultaneous command output (lock command, call to the semaphore), only one time interval elapses Cycle start and the synchronization sequence only takes a small amount of time, in particular, a maximum of one time interval between two successive ones Time signals.

Prefers the processes are in this case designed such that when carrying out the Operating process, in particular with an assignment of the semaphore with the operating process, the monitoring process Is blocked. As a result, only either the semaphore can be used be occupied or have an interrupt lock.

alternative to the implementation a synchronization sequence at the beginning of the cyclic process is provided in a preferred alternative that the cyclic Process at the end of its cycle time and before the beginning of the subsequent one Cycle causes the monitoring process and / or the operating process in a state not disturbing the beginning of the cycle is offset. This assumes that it is in principle is sufficient to ensure in good time before the start of the cycle that the interrupt starting the cyclic process coincides with the time signal takes place. The cyclic process is usually not over the entire cycle time active. For example, the cycle time is one Measuring process 50 ms, whereby the process for reading the measuring signals only a few milliseconds, for example 7 ms needed. The remaining time during the cycle time, the process is inactive. To the disturbing influences of Switching off further processes on time is expedient provided that the process the remaining time until the end of the cycle determined and in good time before the end of the cycle time the measures initiates the disturbing influences to turn off the further processes, i. an interrupt lock of the monitoring process to prevent or to prove a semaphore.

This can be done in different ways. For example, against End of the cycle time from the cyclic process a blocking signal to the monitoring process delivered, giving an interlock lock to the subsequent cycle triggering Interrupt can not be present. There is also the possibility through the use of so-called flags (event flags) the monitoring process only release at defined times. Such a Markie tion is set, for example, at the end of the active time of the process and canceled in time before the end of the cycle time. In time Before the end, this means that there is still enough time left until the beginning of the new cycle is a possible interrupts lock repealed. This usually ranges from one to a few milliseconds out.

Another preferred possibility is to use an intermediate process initiated by the cyclic process or part of the zy is a higher priority than the monitoring process but has a lower priority than the cyclical process. The intermediate process is started in good time before the end of the cycle time, for example a few milliseconds before, so that the monitoring process is ended due to the higher priority. Due to the higher prioritization of the cyclic process, this is then started exactly at the beginning of the cycle time and the beginning of the cycle begins with the start of the cyclic process.

Finally exists in an alternative embodiment, the possibility, depending on specify predefined time slots for the cyclic process, while of which the monitoring process is released is. This is therefore compared to the blocking of the monitoring process acted opposite and the monitoring process active for defined Time intervals released. It will be a so-called Time slot for the monitoring process established.

The Task is according to the invention still solved by an automation system for carrying out the method according to the features according to claim 15. The advantages mentioned in terms of the method and preferred embodiments are analogous to the automation system transferred to.

In a suitable variant is the cyclic process a neutron flux measurement, in particular in a nuclear fission reactor of a nuclear power plant. The neutron flux is the per unit time and area unit occurring number of neutrons. He determines the temporal for a given place frequency the over a neutron capture caused cleavage and is therefore a determining Measure for the local Performance for the area of the nuclear fission reactor in which the measurement is carried out. About these Measured variable is in the nuclear reactor, the local development of nuclear fission reactions regulated. This is done by means of control rods that are stepper motor controlled between the fuel rods in and out and made of a neutron absorbing material are made. Thus lets the number of thermal neutrons that govern nuclear fission reactions to disposal stand. The further the control rods in interspaces between the fuel rods retract, the more thermal neutrons are absorbed, one complete Retraction of the control rods absorbed so many thermal neutrons that nuclear fission reactions completely be stopped and the nuclear reactor is turned off.

at Neutron flux measurement is a very critical one Measuring process, since the measuring cycle is very short and, for example in an order of magnitude of 50 ms. Accordingly, already affect small temporal Variations in the cycle time of the order of a few ms Measurement result strong. However, this result depends on how controllable regulation of nuclear fission reactions in the nuclear reactor takes place, but also in which situations and how fast a complete shutdown he follows.

The Cycle time stabilization procedure therefore allows additional performance internal tests to check the operability of the automation system, without doing the measurement cycle for Neutronenflussmessung to influence. This is the reliability of the nuclear fission reactor improved.

following Be exemplary embodiments of Invention explained in more detail with reference to a drawing. In each show in simplified schematic representations:

1 a schematic of an automation system with a cycle time stabilization,

2 a schematic representation of the timing of a measurement process and a monitoring process with a cycle time stabilization using a synchronization sequence,

3 a schematic representation similar 2 additionally showing the sequence of an operating process when using a semaphore,

4 a schematic representation of the time course of the processes as in 3 assuming that only the monitoring process is active and the semaphore is not occupied by the operator process,

5 a schematic representation of the processes according to the 3 and 4 assuming that only the operating process is active, the semaphore is occupied by the operating process and at the same time the cyclic monitoring process is inactive, as well

6 a simplified representation of the timing of various processes with cycle time stabilization, the measures for the cycle time stabilization are initiated towards the end of the cycle of the cyclic process Corresponding elements are provided in all figures with the same reference numerals.

1 schematically shows an automation system 1 with a processor 2 , The processor 2 is set up in such a way that it uses a process engine management system 3 the access of processes P, B, Ü, W to system resources 8th regulates. The system resources 8th communicate with the sensors 9 and the actors 10 ,

The process P is a cyclic process that includes at least one measurement process M or is a measurement process. The measured values for the measuring process M are from a measuring device 12 measured. Process B is an operating process based on the same system resources 13 accesses like the cyclic process P or the measuring process M. A semaphore 14 regulates access to the shared system resources 13 and ensures that only either the cyclic process P, measuring process M or the operating process B to these system resources 13 accesses.

The process Ü is a monitoring process that periodically performs a check of functions of the automation system. Like other processes W, it attacks the shared system resources 8th to.

The automation system 1 also includes a clock or system timer 16 which periodically outputs time signals S at exactly defined time intervals to the processor 2 be transmitted. Initiated by the time signals S are interrupts 1 triggered, which influence the individual processes P, B, Ü, W.

This in 1 illustrated automation system is implemented in particular in a nuclear facility. The measuring process M is used in particular for the acquisition of measurement data of a neutron flux measurement, which with the measuring device 12 was carried out. In the course of the measuring process, this becomes an absolute counter reading of the measuring device 12 determined and in particular the difference of the count between two consecutive queries. In order to be able to derive therefrom an exact count rate as a measure of the neutron flux, it is of decisive importance that the cycle time T between two queries is exactly constant and known and does not fluctuate or can be measured accurately and in a timely manner. The cycle time T is typically in the range of a few tens to a few 100 ms. At the same time, the low priority monitoring process is continuously running. Also with this process Ü individual states, components, subsystems, etc. of the automation system are periodically queried. The duration of a complete monitoring cycle in a nuclear power plant is typically in the range of several minutes to hours. Operators can continue to manually influence the operation of the system, for example by manually requesting measurement data or manually using actuators 10 influence. For each manual intervention, an operating process B is initiated. In addition, a large number of further processes W are available, which are required for the automated operation of the nuclear installation.

In the 2 to 6 the time sequence of the different processes is plotted in bar form. While the 2 to 5 show greatly enlarged temporal sections of a few time signals S1-S3 in the start region of the measuring process M are in 6 the processes over the period of several cycle times T applied. The total cycle time T is 50 milliseconds in the embodiment and is determined by the distance of a total of 50 time signals S, which are each spaced by 1 ms to each other.

For all embodiments, the measuring process is started by a start interrupt Is. After the cycle time T, the next measurement process M is likewise started again with a start interrupt Is. During the cycle time T, the measuring process M is only active for a certain period of time. For example, the measuring process is capable of performing all the work during the cycle within a few milliseconds. During the remaining inactive time, the resources, ie in particular the computing capacity, are available for the further processes B, Ü. The actual time-critical sub-process within the measuring process M, with the example, the query of the count of the measuring device 12 is called, is referred to below as the readout process Ma and starts with a cycle start Za. Starting from the beginning of the cycle Za, therefore, the actual, time-critical measuring process is active. For the highly accurate measurement, therefore, it is necessary that the cycle time T between two consecutive cycle starts Za be constant and known. The beginning of the cycle Za is triggered by a start interrupt Ia. Only in the imple mentation of the 6 the beginning of the cycle Za coincides with the start interrupt Is.

In 3 Here, a simplified variant of a cycle time stabilization with a time delay of two time intervals is shown, whereas in 2 . 4 and 5 optimized variants are represented with only one time delay delay.

In the embodiments of the 2 to 4 the start interrupt Is is followed by a synchronization sequence or period Q. The synchronization sequence Q runs in the exemplary embodiments of FIG 2 . 4 and 5 only until the next time signal 52 whereas in the embodiment of the 3 the synchronization sequence Q runs until the time after next time signal S3, as will be explained below. Within the synchronization sequence Q, the measurement is effective Process M to the other processes B, Ü such that at the subsequent time signal S2 ( 2 . 4 . 5 ) or to the next time signal S3 ( 3 ) the initial interrupt Ia takes place at the same time as the respective time signal S2, so that a defined beginning of the time is ensured for the beginning of the cycle Za.

at all embodiments it is assumed that the processes M, B, Ü have different priorities, wherein the measuring process M is the highest priority and the monitoring process Ü the least priority having. If a respective process M, B, Ü is to be carried out, is at a Interrupt I each of those process M, B, Ü is activated, which has the highest priority. Run to this If another process B, U lower priority, so will this interrupted.

In the figures, the states of the processes are represented by different hatchings. If the measuring process M or the operating process B is active, this is indicated by hatching reaching from bottom left to top right. Furthermore, the individual processes, in particular the measuring process M, can assume defined waiting states, which are characterized by "PAUSE." The processes M, B are inactive in the white areas of the bars the other processes M, B are active - also active in the white bar areas In the monitoring process Ü an interrupt lock is available from top left to bottom right hatching 20 and by a vertical hatching a Sperrbereich 22 characterized. The interrupts lock 20 indicates an area where the generation of an interrupt 3 is delayed in the presence of a time signal S1, by the time of the interlock 20 , The restricted area 22 indicates the area within which the monitoring process Ü is blocked, ie must not be active.

In the case, that a process influences another process is a directed one Arrow drawn in the vertical direction, that of the influencing points to the influenced process. An initiated by means of an interrupt defined start of a process is completed with a diamond clarified.

Based on 2 For now, the simplified assumption is assumed that only the monitoring process Ü is active. With the time signal S1, the start interrupt Is is triggered. However, because of the activity of the monitoring process Ü, the interrupts lock 20 is effective, the interrupt is Is delayed with time signal S1. The exact time of the start interrupt Is is therefore not exactly defined and thus not suitable for a constant cycle time T. After completion of the interrupts 20 Therefore, if the interrupt Is is present, the monitoring process Ü is terminated due to its lower priority and the measuring process M starts with its synchronization sequence Q. In this case, the measuring process M first becomes active and initiates a blocking command "stop" for the monitoring process U. With this command the monitoring process Ü is disabled until it is explicitly released again by a command "START". The START call here preferably comes at defined times, in particular shortly after the initial interruption Ia. In contrast, the STOP call comes at relatively undefined times. The duration of the lock is, for example, 1 ms. Thus, the end of the lock is already in the next time interval after the time signal S2. Upon completion of the lock, the monitoring process returns to the active phase as soon as higher priority processes are in inactive states.

After a first activity phase during the synchronization sequence, the measuring process switches to a "PAUSE" wait state in order to start the cycle start Za in a defined manner, in which case the wait state is ended with the next interrupt, the initial interruption Ia At the same time as the time signal S2, the actual time-critical read-out process Ma begins with the chronologically defined start of the cycle Za, during which time all necessary actions are carried out to the measuring device 12 read. In particular, drivers Tr are called, which are necessary to use with the measuring device 12 to communicate.

In the embodiment of 3 The assumption is that, in addition to the active monitoring process Ü, the operating process B is also active. In this case, in the first interval between the time signals S1 and S2, the time signal is synchronized with the interrupt I, so that the interrupt I takes place simultaneously with the time signal S2. This is how to 2 described procedure. That is, in the first part of the synchronization sequence Q until the time signal S2, the same process is performed as for 2 described. Subsequent to the time signal S2, the measuring process M, in turn, transitions briefly to an active state and calls the semaphore 14 to prove this. However, in the selected exemplary embodiment, this is still occupied by the latter because of the operating process B still active before the interrupt to the time signal S2. The measurement process M must therefore wait until the semaphore 14 free is. Simultaneously with the call to the semaphore 14 Operator B is informed that he can continue. After a certain period of time, the semaphore becomes 14 free and can be occupied by the measuring process M. Here's a signal from the semaphore 14 transmitted to the measuring process, which activates in the short term and then enters a wait state "PAUSE", in order to wait for the next time signal S3 and the initial interruption I. The assignment of the semaphore by the two processes M, B is illustrated by different hatchings ruptsperre 22 is preferably canceled immediately after the interrupt Ia and before the driver calls Tr by the START call again. Alternatively, the release can also be done after the driver calls Tr.

In the embodiments of the 4 and 5 it is now assumed that only either the operating process B or the monitoring process Ü can be active. In the embodiment of 4 First, the operating process B is active. Due to its higher priority, the monitoring process Ü is inactive. As soon as the operating process B has ended, the monitoring process Ü starts. In the exemplary embodiment, this happens shortly before the time signal S1. For the time signal S1 is therefore the interrupts lock 20 active and the start interrupt Is occurs with a time delay to the time signal S1. The synchronization sequence Q begins again at the beginning of which the measurement process M initiates both the blocking of the monitoring process and at the same time the semaphore 14 call to prove this. Subsequently, the process enters a wait state in order to wait for the next time signal S2 and the associated initial interrupt Ia, so that the cycle start Za takes place at a defined time.

Similarly, in the embodiment of the 5 assumed that only the operating process B is active. At the time signal S1 is the semaphore 14 occupied with the operating process B, so that the measuring process M to the semaphore 14 has to wait. Again, the measurement process M is both in terms of the semaphore 14 as well as with regard to the monitoring process Ü, so tries the semaphore 14 and at the same time block the monitoring process Ü. Once the measurement process M from the semaphore 14 the feedback gets that this is no longer occupied by the operating process B, the measuring process M goes back into a waiting state "PAUSE" to wait for the initial interruption Ia.

In the embodiment of 6 Now another way is taken. Namely, no synchronization sequence Q is provided here at the beginning of the measuring process M. Instead, suitable measures are taken in good time before the end of the cycle time T in order to create the semaphore 14 or to block the monitoring process Ü. And that is in the embodiment of 6 provided that the measuring process shortly before the end of the cycle time T, for example, a few milliseconds before the end of the cycle time T, again becomes active and by the previously already to the 2 to 5 firstly tries to use the semaphore 14 on the other hand to block the monitoring process Ü. In this case, the monitoring process Ü is first blocked by a STOP call and then an attempt is made to occupy the semaphore. This ensures that at the beginning of the next cycle of the measuring process M, when the time signal S _X or S _{x + 50} occurs, the semaphore 14 is free or occupied by the measuring process M and no interrupts 20 is present. In this case, there is no time offset between the time signal Sx or S _{x + 50} and the start interrupt Is triggered thereby. The start interrupt Is is therefore also used as the initial interrupt Ia and the beginning of the cycle Za coincides with the start of the measurement process M. Again, a time-defined cycle start Za is obtained.

The cycle time stabilization measures described here ensure that influences due to an interrupt inhibit 20 and / or by waiting for the semaphore 14 , which can cause a variation of the cycle time T, are excluded. Overall, this ensures a constant and accurate cycle time T, so that, in particular when evaluating measurement results, no errors are to be expected or that the measurement tolerances which can be caused by further effects are markedly reduced compared to a method without such cycle time stabilization ,

1

automation system

2

processor

3

Process Management System

8th

system resources

9

sensors

10

actuators

12

measuring device

13

together used system resources

14

semaphore

16

System timer

20

interrupt disable

22

stopband

B

operating process

I

interrupt

Ia

Anfangsinterrupt

is

Startinterrupt

M

cyclic Measuring process, time course

Ma

selection process

P

cyclic process

Q

synchronization sequence

S, S1, S2, S3

time signal

T

cycle time

Tr

driver

Ü

cyclic monitoring process

Z

between process

Za

cycle start

Claims (14)

Method for stabilizing the cycle time (T) in an automation system ( 1 ) passing between two consecutive cycle starts (Za) of a cyclic process (P, M), whereby at least one further process (B, Ü) is based on identical system resources ( 8th ) and in which the start of the cyclic process (P, M) is triggered by an interrupt (Is) which is triggered by a system timer ( 17 ) periodically emitted time signal (S2) is initiated, wherein the cyclic process (P, M) is designed such that before the beginning of the cycle start (Za) of the further process (B, Ü) in a cycle start (Za) not disturbing state and the beginning of the cycle (Za) takes place simultaneously with a time signal (S2, S3). The method of claim 1, wherein after starting of the cyclic process (P, M), first a synchronization sequence (Q) executed will, while the further process (B, T) is put into a state which does not disturb the beginning of the cycle (Za), and only afterwards at a subsequent interrupt (Ia) the beginning of the cycle (Za) takes place. Method according to Claim 2, in which the further process is a first further process (Ü) which is interrupted by an interrupt ( 20 ), wherein a synchronization between the time signal (S) and the interrupt (I) takes place by a blocking command (STOP) for the first further process (Ü) is caused after a first interrupt (Is), so that at the next time signal ( S2) the interrupts lock ( 20 ) is not effective. The method of claim 3, wherein the lock is the first one further process (Ü) by a start command (START) in particular to a relative to the interrupt (Ia) fixed time is canceled again. Method according to one of the preceding claims, in which a semaphore ( 14 ) is provided, the access of the cyclic process (P, M) and a second further process (B) on the system resources ( 13 ), whereby the cyclic process (P, M) the semaphore ( 14 ) before the beginning of the cycle (Za). Method according to Claim 3 or 4 and 5, in which the interrupt (Is) contains a lock command (STOP) for the first further process (Ü) and a call to the semaphore ( 14 ) is submitted to prove this. Method according to claim 3 or 4 and 5 or 6, wherein during the occupation of the semaphore ( 14 ) is blocked with the second further process (B) of the first further process (Ü). The method of claim 1, wherein the cyclic Process (P, M) at the end of its cycle time (T) and before the beginning of the subsequent cycle causes the further process (B, Ü) to become one not disturbing the beginning of the cycle (Za) Condition is shifted. Method according to one of the preceding claims, in the cyclic process (P, M) has the highest priority and in the case of an interrupt (I, Is, Ia), the process with the highest priority is started is, if its execution is applied. Method according to one of the preceding claims, in the cyclic process (P, M) a measuring process (M) for detection of measured data, in particular for neutron flux measurement in a nuclear technology Plant includes. Method according to one of the preceding claims, in which the further process is a monitoring process (Ü) with which the functionality of the automation system ( 1 ) is constantly monitored. Method according to one of the preceding claims, in the further process is an operating process (B). Automation system ( 1 ) for carrying out the method according to one of the preceding claims with a processor ( 2 ), a process management system ( 3 ) for controlling processes (P, M, Ü, B, W) and a system timer ( 17 ) for generating a periodically emitted time signal (S1-S3), wherein a cyclic process (P, M) and another process (Ü, B, W) are provided which are based on identical system resources ( 8th ), the process management system ( 3 ) is designed such that the start of the cyclic process (P, M) is triggered by an interrupt (Is) which is triggered by one of the system timers (P, M). 17 ) and wherein the cyclic process (P, M) is designed such that before the start of a cycle start (Za) of the cyclic process (P, M) of the further process (Ü, B) in a the beginning of the cycle (Za) not disturbing state is added and the beginning of the cycle (Za) takes place simultaneously with a time signal (S2, S3). Automation system ( 1 ) according to claim 13 in a nuclear facility.