Method and apparatus for safety-related communication in a communication network of an automation system

• US 20110069698A1
• Filed: 09/09/2010
• Published: 03/24/2011
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Phoenix Contact GmbH & Company KG
• Original Assignee: Phoenix Contact GmbH & Company KG
• Inventors: Schmidt, Joachim, Horn, Steffen
• Granted Patent: US 8,923,286 B2
• Time in Patent Office: Days
• US Class Current: 370/351
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/462 LAN interconnection over a bridge based backbone
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00

Abstract

The invention relates to communication between safety-related modules in a communication network of an automation system. The object of the invention is to simplify installation and development of safety-related modules in an automation network. To this end, the safety functions of a system are divided into small, manageable, locally delimitable and simply verifiable groups of modules.

Claims

1. An automation system comprising:

a non-safe communication master; and

a plurality of local modules, the local modules being adapted as network subscribers, and being connected to the communication master via a communication network,

wherein communication between the local modules in the communication network is realized via telegrams, wherein at least two of the local modules are safety modules between which safety-related data are transferred and that form a logical group of modules for performing a safety-related function, and

wherein the non-safe communication master maintains a routing table that stores logical connections between the local safety modules in accordance with the safety-related function, the communication master being adapted to control automatic routing of data from a transmitting safety module to a receiving safety module in function of the routing table, such that each communication among the safety modules of one logical group occurs via two point-to-point connections, namely from the transmitting safety module to the communication master and then from the communication master to the receiving safety module,

wherein the receiving safety module is adapted to perform a safety-related action according to the received data, and

wherein the communication network includes a means to retrieve information from the safety modules for establishing the routing table, and to establish the routing table on the basis of the information.

2. The automation system according to claim 1, wherein the communication master is adapted to perform the following steps to initialize the routing table:

a) determining the configuration of the connected network,

b) determining identification information of the connected safety modules,

c) performing a plausibility check, if applicable,

d) establishing an instruction or copy list for the routing of telegrams in cyclic operation from the information resulting from steps a) and b).

3. The automation system according to claim 1, wherein the communication master is adapted to retrieve information from the safety modules connected to the communication network, and to determine from the retrieved information which safety modules are allocated to a respective logical group, and to realize the connections in the routing table in accordance with the allocation of the safety modules.

4. The automation system according to claim 1, wherein the addresses of the safety modules are configured such that it reflect a collective allocation to a respective logical group.

5. The automation system according to claim 1, wherein the transfer of safety-related data occurs in telegrams via a non-safe channel, and wherein, for error-proof transfer of the safety-related data, the receiving safety module is adapted to detect errors with regard to permutation, corruption, misrouting or deterioration of telegrams.

6. The automation system according to claim 5, wherein the receiving safety module checks a received telegram for at least one of the following characteristics:

the time stamp,

redundancy,

a check sum,

a sequential telegram number,

a transmitter identity

a receiver identity.

7. The automation system according to claim 6, wherein the communication master is adapted to allocate logical groups to specific address spaces.

8. The automation system according to claim 1, wherein among the safety modules of a logical group is at least one safety module that comprises an input module and at least one safety module that comprises an output module wherein the output module is adapted to initiate a safety function in response to a telegram from an input module.

10. The automation system according to claim 5, characterized in that the receiving safety module checks a received telegram for all of the following characteristics:

the time stamp,

redundancy,

a check sum,

a sequential telegram number,

a transmitter identity

a receiver identity.

9. (canceled)

11. A method for monitoring safety functions in an automation system comprising a non-safe communication master and a plurality of local modules, the local modules being adapted as network subscribers and being connected to the communication master via a communication network, and communication between the local modules in the communication network being realized via telegrams, the method comprising:

retrieving information from safety modules for establishing a routing table that stores logical connections between the safety modules in accordance with a safety-related function, wherein at least two of the local modules are the safety modules between which safety-related data are transferred and that form a logical group of modules for performing the safety-related function;

maintaining, at the communication master, the routing table on the basis of the information retrieved;

automatically routing, through the communication master, data from a transmitting safety module to a receiving safety module in function of the routing table, such that each communication among the safety modules of one logical group occurs via two point-to-point connections, namely from the transmitting safety module to the communication master and then from the communication master to the receiving safety module; and

performing, at the receiving safety module, the safety-related action according to the received data.