DE10048747A1 - Method for handling processing signals in automated installation process, involves using first processing unit capturing processing signals in processing cycle and generating single messages from these for forwarding on. - Google Patents

Abstract

Independent of the volume of incoming processing signals (P), a maximum number (MP) is preset for single messages (Ex) generated in a processing cycle. Primary signals (P,A) to be adapted to the single messages are formed from the processing signals or from signals branched off from these and are store temporarily in a first memory (12). The MP lies in a range for the time average of the number of processing signals arriving per processing cycle.

Description

The invention relates to a method for processing Pro process signals, in particular for processing process signals len of a plant process.

In a system, for example in an automation plant, a large number of individual components are provided, which communicate with each other in particular via a bus system ren. By means of, for example, a fieldbus Bus systems become the process signals of the individual components transmitted to processing units. In the case of complex layers are usually a variety of such processing units are provided, which are mostly structured hierarchically. In particular, in addition to a large number of decentralized processors processing units a central processing unit hen, for example as part of a central control o the control room. In the decentralized processing units he follows a first processing of the process signals by be prepared for individual reports. For this, the one For example, an identifier is assigned to individual process signals and further processing steps are carried out. In the central processing unit is then the under different individual reports evaluated.

An essential point for this evaluation is in one to see timely evaluation of the individual process signals. This is particularly important if the single mel different processing units be compared and the temporal order of the process signals for the evaluation is essential. This is at for example in the event of an accident of high interest, if of multiple processing units in the shortest possible time to determine where the error is going has just occurred. As an accuracy for such  Precise or time-synchronous evaluation of the process signals is typically less than 10 milliseconds the aimed.

An essential criterion for the time accuracy is the Duration of a processing cycle of the respective dec central processing unit. The processing cycle includes the detection of the process signals, the generation of the pro Individual messages assigned to process signals and their transmission to the central processing unit. The processing cycle thus includes an acquisition period, a processing period and a broadcast period. A process signal, for example during the processing period for decentralized processing processing unit is received only with the next processing processing cycle processed. The time accuracy is therefore ent depending on the duration of the processing cycle Right. A temporal resolution of the individual process signals is not given within a processing cycle.

One problem now is that with fluctuating time accuracy for the individual processing cycles varies, so that a statement about the actual Zeitge accuracy can not be made. In particular thereby the resulting newspaper inaccuracy in a ver from individual reports from several decentralized processors processing units increased. A fluctuation in the length of time Processing cycle is particularly from one fluctuating process signal amount. Because the time Duration of a processing period depends on the number of pro cess signals.

The invention has for its object a processing of To enable process signals with high time accuracy.

The object is achieved according to the invention by a method ren for processing process signals, in particular of a user location process in which a first, especially decentralized  Processing unit in one processing cycle the Pro Process signals recorded, generated from these individual messages and provides the individual messages for forwarding, whereby ei ne maximum number of times during a processing cycle Generable individual messages specified and independent of the Amount of incoming process signals is.

Limiting the number of process signals that occur in the course of a processing cycle processed into individual messages ensures a constant processing period and thus an essentially constant process of the same length processing cycle, regardless of the amount of incoming pro zesssignalen. Using this method is therefore more advantageous Way a variable or fluctuating input load on one Signal input of the first processing unit to a con constant processing load or constant output load det.

Primary signals, which are derived from the process signals len or are formed from signals derived from these, and which are prepared for the individual reports in one cached first memory. This ensures represents that even with a fluctuating process signal quantity all process signals recorded and no information lost go. The use of the first memory enables that Processing of incoming during a processing cycle process signals over several processing cycles divide. This design is based on the idea at ei high load, i.e. a high number of process signals, store them temporarily and then successively in the Ver Process from low-load periods to individual reports and thereby dismantling. Will be under light load periods here processing cycles with a small accumulating Process signal quantity understood.

To achieve the highest possible time accuracy, the Processing period kept as short as possible and in particular  on the to the respective first processing unit waiting process signal volume adjusted. For this lies the maximum number of times during a processing cycle producible single messages in the area of the time average value of the number of pro received per processing cycle process signals. This ensures that at the same time tel all process signals are processed and none Information is lost.

To the amount of Da to be processed and forwarded to keep as low as possible per processing cycle, who preferably only changes in the process states of the plant process recorded and evaluated. This is expediently provided the process signals on changes monitoring and when a specific change occurs Process signal a change assigned to this process signal generating signal as the primary signal and only this to process a single message.

A time information is expediently given to the primary signals stamped in the form of a time stamp. This will also regardless of the storage duration of a process signal in the first memory an exact chronological assignment of the primary si enables the occurrence of the process signal.

The same time stamps are advantageously added arranged primary signals, which at the same time the same processing tion cycle are assigned together in a memory block to which the time stamp is assigned. So it is not necessary, each primary signal has its own time stamp assign, but the timestamp is preferably only one times, namely the memory block. In this dish cherblock then only the primary signals are stored, the are assigned to this time stamp. This makes processing processing capacity and thus the processing period kept as short as possible.  

Different process signals are expedient assigned to different channels, and the memory block has a number of individual storage locations, each of which a specific channel is permanently assigned. This has the intent part that the mapping between the channel and the memory is fixed and not only with every processing cycle must be defined. As a result, the processing load in the With regard to the storage of the process signals or the latter assigned primary signals largely independent of the actual signal volume.

In addition, this fixed allocation between memory space and channel advantageously used to the Er testify to the individual message from the position of the storage space derive a signal identifier that is assigned to the individual message will. In addition, the individual message is additional the time stamp and a pro contained in the primary signal assigned process information. The single message therefore contains the complete and evaluable information, what, when, where has happened.

The individual reports are expediently sent before their Forwarding temporarily stored in a second memory. Since the forwarding is usually carried out via a bus, the may have a fluctuating transmission capacity thus independence from the possible data throughput achieved on the bus line. So while the first store buffers a fluctuating input load is the second memory to buffer or compensate for differences provided transmission capacities on the bus line. Overall, this process with the two storage or buffer systems have a constant processing cycle and so that a constant and high time accuracy is achieved.

The individual messages are expediently in the second Memory grouped into message blocks, since these with regard  on forwarding and transmission in the bus advantageous are imprisoned.

To ensure initial value recording in the event of a malfunction, So the acquisition of the first incoming process signals If the storage capacity is exhausted, they remain on the first Processing unit incoming process signals Untitled.

To transmit the individual reports and preferably the Message blocks to a second, preferably central processing unit is connected to this from the first processing a message signal is transmitted as soon as the individual messages are provided for forwarding. This enables that the second processing unit the respective message blocks at a time when it is processing ca has free capacity.

As an alternative to this, it is provided that a constant number of single messages cyclically to the second Processing unit is forwarded.

An embodiment of the invention is described below hand of the figures explained in more detail. It each show in sch mathematical representation:

Fig. 1 is a diagram of a method for processing of process signals and

Fig. 2 shows the time course of frequency of the received process signals relative to the time course of frequency of single messages to be prepared on process signals.

According to Fig. 1 2 process signals P to a first, remote processing unit 4 is transmitted from a system process. In this, the process signals P are processed into individual messages E _X , which are forwarded to a second central processing unit 6 . The index "X" stands for a large number of discrete individual messages, which are numbered consecutively in FIG. 1.

The plant process 2 is, for example, an automation process in which different plant components are provided, each of which transmits process signals P to the first processing unit 4 . Each of these individual components, ie each type of process signal P, is assigned a channel K _n . The index "n" here also stands for a multiplicity of discrete channels K _n numbered consecutively in FIG. 1. These can be implemented in terms of hardware by means of different input channels in the first processing unit or else in terms of software by means of identification information in the process signal P. The different channels K _{n of} the system process 2 are shown schematically by a diagram 8 , on the ordinate of which the channels K _n (indicated by horizontal dashes) and the frequency P _{H of} the process signals P occurring (process signal frequency) are plotted against time t , The process signal frequency P _H is represented by a curve 10 .

The fluctuating process signal volume represented by curve 10 defines a fluctuating input load for the second processing unit 4 . According to the invention it is provided to map this fluctuating input load to a largely constant processing load or output load.

This basic principle is illustrated in FIG. 2, in which the process signal frequency P _H and the frequency of the individual messages E _H (message frequency) are plotted against the time t.

The course of the process signal frequency P _H is characterized by cyclically occurring load peaks, between which there is only a low base load. This course is typical, for example, for a manufacturing process in which a workpiece is machined by a machine (system component) and then passed on to the next system component. Comparatively few process signals P are emitted during the machining of the workpiece. At the end of machining, the workpiece is ejected, the machine may have to reset and a conveyor belt may have to be moved on, so that a large number of actions are necessary at this point in time, which is never reflected in a large amount of process signals.

As can be seen in FIG. 2, this periodic load is mapped to a constant constant load, which is represented by the frequency of reports E _H. The constant value of the message frequency E _H corresponds to a predetermined maximum number N _{max of} the individual messages E _X to be generated per processing cycle. For the shortest possible processing cycle, it is provided that the maximum number N _{max of} the individual messages E _X generated per processing cycle is based on the temporal average M of the process signals P per processing cycle. This measure ei ne largely constant permanent load for the decentralized processing unit 4 is achieved. In order to reserve a certain reserve capacity for unforeseen events, the maximum number N _{max of} the individual messages E _X that can be generated can be set somewhat above the time average M.

Because of this constant constant load, the processing load for the first processing unit 4 is essentially constant. The width of the individual bars at the message frequency E _H corresponds to the duration of a processing cycle of the first processing unit 4 . A constant number of individual messages E _X from the individual process signals P is thus processed per processing cycle. As a result, the load per processing cycle is independent of the quantity of incoming process signals P and largely constant. Due to the uniform load per processing cycle, which is reflected in a constant time duration of the individual processing cycles, high time accuracy is achieved. A high level of time accuracy is particularly necessary in order to be able to analyze the individual messages E _X transmitted from different decentralized processing units 4 to the central processing unit 6 . A prerequisite for a time differentiation of the individual individual messages E _X is high time accuracy.

As already explained, the basic idea for achieving the time accuracy is to map a fluctuating input load to an essentially constant processing load. In order not to lose any information, a buffer system 12 with a first memory 14 and a second memory 16 is provided in the first processing unit 4 . This is shown in FIG. 1, on the basis of which the processing of the process signals P to the individual messages E _{X is} explained: the incoming process signals P are monitored in a comparator 18 for changes, ie the state of the respective process signal P of a channel K _n im previous processing cycle is compared to the current state. If there is a change, a change signal A is generated by the comparator 18 . The information relating to the individual channels K _n is maintained by the comparator 18 in order to ensure that the respective process signal P is assigned to the respective system component.

The change signals A are temporarily stored in the first memory 14 . Namely, the change signals A detected during a processing cycle are stored in a memory block B _m assigned to the respective processing cycle. Each of these memory blocks B _m is assigned time information in the form of a time stamp T _m . The time stamp T _m is generated by an internal clock, not shown, of the first processing unit 4 , namely a time stamp T _{m is} assigned to each processing cycle. The internal clock is synchronized with other clocks in the individual processing units in a manner known per se.

The index “m” here also stands for a multiplicity of individual memory blocks B _m , which are each assigned change signals A at a processing cycle assigned to the time stamp T _m .

During a processing cycle, only one memory block B _{m is written to} . Referring to FIG. 1, this is the memory block B1. Each of the memory blocks B _m in this case has ei ne to the channels K _n corresponding number of storage locations _n to S, wherein a respective space S _n K _n a particular channel is assigned. If a change occurs in a specific channel K _n , this channel K _{n is assigned} a change signal A and this is assigned in an assigned memory location S _n in the memory block B _m . According to the exemplary embodiment, changes have been made to channels K1, K2 and K4, for example, which are stored in the assigned memory locations S1, S2, S4 in memory block B1. This is indicated by crosses. In the first memory 14 , the memory blocks B _{m are represented} by rows and the memory locations S _n by columns.

The memory blocks B _m thus described are temporarily stored in the first memory 14 . A constant number of the change signals A stored in the individual memory blocks B _m is now processed into individual messages E _X per processing cycle.

These single messages are E _X amount sums together in message blocks 22 in which each message block 22 is associated with a fixed number of single messages E _X. The individual messages can be ordered either according to the time stamp T _m or according to the respective channel K _n . That is, in a special message block 22 only individual messages E _X with the same time stamp T _m or only individual messages E _{X of a} specific channel K _{n are} combined.

To generate the single messages E _X of the storage space S is from the position _n of the respective change signal A, a signal identifier and J of the respective memory block B _m assigned to parent timestamp T _m. In addition, the individual message E _X also includes the process information contained in the change signal A about the change in the process state that has taken place.

In the method described here, a substantially constant load and thus high time accuracy is achieved by means of the buffer system 12 per processing cycle of the first processing unit 4 . Due to the two-tier buffer system 12 with the first memory 14 and the second memory 16 , both a variable, fluctuating input load is buffered and a fluctuating transmission capacity on the bus line to the second, central processing unit 6 is taken into account. Overall, it is thereby achieved that a high time resolution of all incoming information is made possible regardless of the amount of incoming process signals P and regardless of the transmission capacity on the bus line.

In the event of a serious disruption in the process flow, there will generally be a large amount of process signals P, which may result in the memory capacity of the first or second memory 12 , 14 being exceeded. In this case, the process signals P arriving later are no longer recorded. This ensures that the process signals arriving first can later be evaluated by the central processing unit 6 (initial value acquisition).

Standard mechanisms are used for the transmission of the individual message blocks 22 to the second processing unit 6 . In particular, a notification signal MS is transmitted to the second processing unit 6 from the first processing unit 4 when a ready-for-dispatch message block 22 is present . The message block 22 is then called up by the second processing unit 6 as soon as it has free capacity here. As an alternative to this transmission mechanism, a predetermined amount of individual messages E _X or message blocks 22 can also be periodically and automatically delivered to the second processing unit 6 per processing cycle. This results in a periodic and constant output load, which corresponds to the individual message frequency E _H , as shown in FIG. 2.

Claims (13)

1. Method for processing process signals (P), in particular a plant process ( 2 ), in which a first processing unit ( 4 ) detects the process signals (P) in a processing cycle, generates these individual messages (E _X ) and generates the individual messages ( E _X ) provides for forwarding, a maximum number (N _max ) of the individual messages (E _X ) that can be generated during a processing cycle being predetermined and being independent of the quantity of incoming process signals (P). 2. The method as claimed in claim 1, in which primary signals (P, A) to be prepared for individual messages (E _X ), which are formed from the process signals (P) or from signals (A) derived therefrom, in a first memory ( 12 ). be stored temporarily. 3. The method as claimed in claim 1 or 2, in which the maximum number (N _max ) of the individual messages (E _X ) which can be generated during a processing cycle is in the range of the time average (M) of the number of incoming process signals (P) per processing cycle , 4. The method according to any one of the preceding claims, in which the process signals (P) are monitored for changes and, when a process signal (P) changes, a change signal (A) is generated as the primary signal and this is further processed into an individual message (E _X ) , 5. The method according to any one of claims 2 to 4, wherein the primary signals (P, A) with a time stamp (T _m ) who the. 6. The method according to any one of claims 2 to S. in which the same time stamp (T _m ) associated primary signals (PA) are stored together in a memory block (B _m ) to which the time stamp (T _m ) is assigned. 7. The method according to claim 6, in which different process signals (P) are assigned to different channels (K _n ), and the memory block (B _m ) has a number of individual memory locations (S _n ), each of which has a specific channel ( K _n ) is permanently assigned. 8. The method according to claim 7, wherein the respective individual message (E _X ) from the assigned primary signal (P, A) is formed by the individual message (E _X ) the time stamp (T _m ), one from the position of the memory location ( S _n ) derived signal identifier (J) and a process information contained in the primary signal (P, A) is assigned. 9. The method according to any one of the preceding claims, wherein the individual messages (E _X ) are temporarily stored in a second memory ( 16 ) before they are forwarded. 10. The method according to claim 9, wherein several of the individual messages (E _X ) are combined in a message block ( 22 ) and temporarily stored in the second memory ( 16 ) 11. The method according to any one of claims 2 to 10, in which Exhausted storage capacity the incoming process signals (P) are disregarded. 12. The method according to any one of the preceding claims, in which a message signal (MS) is transmitted from the first processing unit ( 4 ) to a second processing unit ( 6 ) as soon as the individual messages (E _X ) are ready for forwarding. 13. The method according to any one of claims 1 to 11, in which a substantially constant number of individual messages (E _X ) is cyclically forwarded to a second processing unit ( 6 ).