Safety network system and safety slaves and safety controller and communication method and information gathering method and monitoring method in safety network system

• US 20040181296A1
• Filed: 04/30/2004
• Published: 09/16/2004
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Nakamura, Toshiyuki, Nakayama, Teruyuki, Muneta, Yasuo
• Granted Patent: US 7,162,311 B2
• Time in Patent Office: Days
• US Class Current: 700/21
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 2219/14114 Integrity, error detector, switch off controller, fail safe

Abstract

A safety PLC 1 and at least a safety slave unit 2 are connected through a safety network 3. The safety slave unit has the safety information transmission function for transmitting the safety information for determining whether a safe state prevails or not and the unsafety information transmission function for transmitting the unsafety information containing no safety information. The unsafety information transmission function transmits the unsafety information on condition that the safety slave unit is in a safe state. Specifically, in the case where it is determined that no safe state prevails at the timing of transmitting the unsafety information, the unsafety information is not sent but the safety is transmitted. A safety controller, upon receipt of the unsafety information, estimates that the safety slave unit at the transmitting end of the particular unsafety information is in a safe state.

Claims

1. A safety network system constructed by connecting a safety controller and safety slave units through a safety network, characterized in that:

the safety slave units each have the safety information transmission function for transmitting the safety information for determining whether a safe state prevails or not and the unsafety information transmission function for transmitting the unsafety information containing no safety information; and

the unsafety information transmission function transmits the unsafety information on condition that the safety slave units are in a safe state.

2. The safety network system according to claim 1, characterized in that the safety slave units transmit a safety without sending the unsafety information in the case where it is determined that no safe state prevails at the timing of transmitting the unsafety information.

3. The safety network system according to claim 1, characterized in that the safety controller, upon receipt of the unsafety information, estimates that the safety slave unit constituting the transmitter of the unsafety information is in a safe state.

4. A safety slave unit for connecting to a safety network system constructed by connecting a safety controller and the safety slave unit through a safety network, characterized by comprising:

the safety information transmission function for transmitting the safety information for determining whether a safe state prevails or not and the unsafety information transmission function for transmitting the unsafety information containing no safety information; and

characterized in that the unsafety information transmission function transmits the unsafety information on condition that the safety slave unit is in a safe state.

5. The safety slave unit according to claim 4, characterized in that

it is determined whether the request received from the safety controller is a request for the safety information or the unsafety information,

in the case where the received request is a request for the safety information, the safety information is transmitted, and

in the case where the received request is a request for the unsafety information, the unsafety information is transmitted as long as the safety slave unit is in a safe state, and the safety information is transmitted as long as the safety slave unit is not in a safe state.

6. The safety slave unit according to claim 4, comprising unsafety information transmission control means for controlling the timing of transmitting the unsafety information,

characterized in that the unsafety information is sent on condition that a safe state prevails at the timing of transmission.

7. A safety controller adapted to be connected to a safety network system constructed by connecting a safety controller and safety slave units through a safety network, characterized by comprising:

a fail-safe processing function for analyzing the contents of the safety information received from the safety slave units and in the case where it is determined that no safe state prevails, executing a predetermined process; and

a function of estimating that the safety slave unit at the transmitting end is in a safe state in the case where the unsafety information is received.

8. The safety controller according to claim 7, characterized by comprising unsafety information request control means for controlling the timing of issuing a request to transmit the unsafety information.

9. A communication method for a safety network system constructed by connecting a safety controller and a safety slave unit to each other through a safety network, characterized in that:

the safety slave unit executes the process of transmitting one of the safety information for determining whether a safe state prevails or not and the unsafety information containing no safety information toward the safety controller through the safety network at an appropriate timing; and

the process of transmitting the unsafety information is executed on condition that the safety slave unit is in a safe state.

10. An information collecting method for a safety network system constructed by connecting a safety controller and a safety slave unit to each other through a safety network, characterized in that:

the safety slave unit has the safety information transmission function for transmitting the safety information for determining whether a safe state prevails or not and the unsafety information transmission function for transmitting the unsafety information containing no safety information, the unsafety information transmission function transmitting the unsafety information on condition that the safety slave unit is in a safe state;

the safety slave unit, when transmitting information toward the safety controller, determines which of the safety information and the unsafety information is to be transmitted, and transmits the information thus determined through the safety network; and

the safety controller receives the safety information or the unsafety information sent thereto through the safety network, and in the case where the received information is the unsafety information, stores the information based on the unsafety information.

11. A monitor method for a system constructed by connecting a monitor device further to a safety network system constructed by connecting a safety controller and a safety slave unit through a safety network, characterized in that:

the safety slave unit has the safety information transmission function for transmitting the safety function for determining whether a safe state prevails or not and the unsafety information transmission function for transmitting the unsafety information containing no safety information, the unsafety information transmission function transmitting the unsafety information on condition that the safety slave unit is in a safe state;

the monitor device acquires the unsafety information transmitted from the safety slave unit toward the safety controller; and

the acquired unsafety information is analyzed and the information based on the unsafety information is stored.