DE102022126354B3 - Method for automatic address assignment in an AS-I master-slave bus system - Google Patents

Abstract

In an AS-I master-slave bus system, the method according to the invention uses randomly controlled mechanisms in the slave to check in the addressing phase whether there is double addressing and, if this is the case, a new address is generated on the slave side.

Description

The invention relates to a method for automatic address assignment in an AS-I master-slave bus system.

Bus systems are often used in automation technology, both in production automation and in process automation. They are used to forward information from sensors to controllers or to control actuators via controllers. In certain cases, the controllers are still connected to higher-level bus systems, some of which are connected to company networks (TCP/IP protocol family).

From the DE19733906A1 a method for automatic address assignment in a general master-slave bus system is known, which is based on a complex distance measurement.

From the DE 102014117797 A1 Dynamic addressing of slave units in a master-slave bus system is known.

From the documents DE10206657A1 , DE10253566A1 , DE102006050135A1 , DE102007025852B3 , DE102009033229A1 , DE102011101172A1 , DE102013216564A1 , EP2348374A1 and WO2013013710A1 Various bus systems and methods for double address recognition are known.

Examples of master-slave bus systems are Profibus, Interbus and especially the AS-i bus system. AS-i stands for actuator-sensor interface. Further information about this bus system can be found in “AS-i the actuator-sensor interface for automation”, Professor Dr. W. Kriesel and Dr. O. W. Madelung, Hanser-Verlag Munich Vienna 1994 or “AS-Interface: the solution in automation”; published by the AS-International Association 2002. The AS-i bus system in particular is based on the master-slave principle, in which the master cyclically polls the slaves connected to the bus line via a master telegram (cyclic polling) and the slaves with a respond to the corresponding slave telegram. The response time of the bus system is less than 5 milliseconds.

The maximum number of slaves that can be connected to the bus line is 31 in normal mode or 62 in extended mode. An important aspect of the AS-i bus system is that data transmission and power supply to the slaves take place via the same line (two-wire line).

An AS-I bus system is described in more detail in DE50209644D1.

The slaves or the slave units for an AS-I bus system always have the address 0 when delivered and can be controlled by the master or the

Therefore, the master unit cannot be addressed individually. However, a default address other than 0 cannot be used, as the residual risk of double addressing cannot be ruled out.

Known auto-addressing methods (such as DHCP) cannot be used because the individual slaves are only allowed to respond to a master call and cannot send a registration telegram to the master on their own.

In building automation as a sub-area of automation technology, AS-i slaves are often just wired during installation without being addressed.

For addressing, i.e. H. To set the address, access to each individual slave is required when commissioning the AS-I bus system, which can be very problematic under certain circumstances if the slaves are inaccessible, for example. B. are arranged in false ceilings, which requires the use of lifting platforms. The slaves may also be located in restricted access areas.

The object of the invention is therefore to provide a method for automatic address assignment in an AS-I master-slave bus system that does not have the disadvantages mentioned above and that can be implemented easily and inexpensively.

This task is solved by the method specified in the claim.

The method according to the invention is explained in more detail below using a drawing.

• 1: AS-i Bussystem mit einer Mastereinheit und drei Slave-Einheiten Anhand der 1 ist beschrieben, wie der AS-I-Master in der Adressierungsphase durch entsprechende Masteraufrufe einzelne Slave-Adressen überprüft.
  • • Der AS-i Master (Master-Einheit) sendet zyklisch in aufsteigender Reihenfolge an jede AS-i Adresse (Slave-Einheit) Ausgangsdaten. Die physikalische Reihenfolge der Slave-Einheiten auf dem Kabel spielt bei der AS-i Kommunikation keine Rolle. Nur die Adressreihenfolge ist ausschlaggebend.
  • • Das passend adressierte AS-i IC (in der Slave-Einheit) liefert die Daten an seinem Ausgang und signalisiert den Datenaufruf am Ausgang „data strobe“. Die Daten können z. B. an einen µController übergeben werden.
  • • Das AS-i IC sendet die am Daten-Eingang anstehenden Daten als Slave-Antwort an den Master. Die Daten können von einem µController an das Slave IC übergeben werden.
  • • Antwortet ein AS-i Slave nicht auf einen Master-Aufruf, wiederholt der AS-i Master seinen Aufruf unmittelbar. Das kann der µController am Datastrobe-Signal erkennen.

It shows:

• 1 : AS-i bus system with one master unit and three slave units Based on the 1 describes how the AS-I master checks individual slave addresses in the addressing phase using appropriate master calls.
  • • The AS-i master (master unit) cyclically sends output data to each AS-i address (slave unit) in ascending order. The physical order of the slave units on the cable plays a role in AS-i communication tion doesn't matter. Only the address order is important.
  • • The appropriately addressed AS-i IC (in the slave unit) supplies the data at its output and signals the data call at the “data strobe” output. The data can e.g. B. be transferred to a µController.
  • • The AS-i IC sends the data present at the data input to the master as a slave response. The data can be transferred from a µController to the slave IC.
  • • If an AS-i slave does not respond to a master call, the AS-i master repeats its call immediately. The µController can recognize this from the data strobe signal.

• In der Ausgangslage sind mehrere AS-i-Slaves mit der Adresse 0 angeschlossen. Der Master ist im Projektierungsmodus und fragt alle möglichen Slave-Adressen ab. Antwortet kein Slave auf den Aufruf, wiederholt der Master den Aufruf einmal sofort. In bis zu zwei weiteren Master-Zyklen versucht der Master den Slave zu erreichen (In Summe 3 mal 2 Aufrufe). Danach wird der Slave als fehlend gekennzeichnet.

The essential process steps are explained in more detail below:

• In the initial situation, several AS-i slaves with address 0 are connected. The master is in configuration mode and queries all possible slave addresses. If no slave responds to the call, the master repeats the call once immediately. The master tries to reach the slave in up to two further master cycles (in total 3 times 2 calls). The slave is then marked as missing.

Step 1: Initial addressing

After the AS-i voltage is switched on, all slave addresses address themselves depending on an identifier (e.g. serial number or AS-i MAC address). This can result in double addresses.

Step 2: Check for duplicate addresses

This sequence described below occurs iteratively until no more duplicate addresses are found.

The slave units themselves recognize whether there are other slaves that use the same address and then look for another address.

The double address can be detected, for example, by the slave with address N not responding to the master call at random intervals and observing whether another slave responds or the call is repeated (monitoring data strobe). If no other slave responds to the first call, slave N answers the repeat call and keeps its address. If, on the other hand, there is no repetition, the address N is assigned elsewhere and the slave N has to choose a new address.

If the slave can decode the calls and not just evaluate the data strobe, it finds possible free target addresses by looking for telegram repetitions.

Step 3: (Final state and normal operation):

For example, various masters enable double address detection by evaluating the signal form of a slave response to a master call.

As soon as the master no longer finds a double address in the network, it ends the addressing mode of the slaves with a command or by setting a defined parameter. The addressing mode can also be ended after a sufficiently long time, assuming that a stable state without double addresses has been established.

The slaves then no longer check their own addresses and respond to every master call to their address.

Now the customer application can use CTT mechanisms via the master to read out individual identifiers (e.g. AS-i-MAC or serial number) and to reassign the addresses if necessary or to compare an address mapping table with the application.

A PC application (e.g. ifm electronic gmbh, moneo) can identify all AS-i masters in the network and list the slaves connected to them. Each slave receives a system address, which consists of the network address of the gateway, the master number within the gateway and the AS-i address of the slave (example 192.168.0.1-0-12A). Alternatively, the use of IPv6 Unique Local Addresses (ULA), described in RFC 4193, is possible and sensible for AS-i slaves. The IPv6 ULA is determined as the system address taking into account the gateway address and the AS-i address. A handheld can connect to the application via a suitable interface (e.g. WLAN and WEB interface) and set each individual slave into flashing mode via a command. The slave identified in this way can then be correctly assigned in the application. For this purpose, a mapping can be carried out between the system address and the logical address.

If a handheld can read the AS-i-MAC from the slave optically (QR code) or via NFC and is connected to the PC application, this information can be combined with the system address to achieve mapping.

The essential idea of the invention is that in AS-i slave units that have a slave IC and a microcontroller, randomly controlled mechanisms are used to check whether there is a double address assignment. If this is the case, the slave unit automatically searches for free addresses in order to re-address the slave unit if necessary. After a certain time in the addressing phase, a stable state should arise in which there is no longer any double addressing in the system and all slaves can be addressed by the master.

Claims (1)

Method for automatic address assignment in an AS-I master-slave bus system characterized by the following process steps: A) Connection of several slave units to an AS-I bus line B) Activation of the power supply of the bus system in order to initiate an addressing phase C) Random Generation of a slave address in the slave units based on an identifier stored in the slave units D) Checking which slave addresses have been assigned by the master unit during the addressing phase through the following intermediate steps: a. Successively sending a master call to the individual slave addresses b. If there is no slave response, repeat the master call to the unanswered slave address c. In order to exclude double address assignment, the slave units carry out the following procedural steps: i. Randomly ignoring master calls by the slave units ii. If the ignoring slave unit detects a slave response from another slave unit that must have the same slave address, the ignoring slave unit increases its address by at least the value 1 E) End the addressing phase if the master no longer finds duplicate addresses in the network. F) Send a command to the slave units to exit addressing mode and respond to all master calls

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