Safety network system and safety slave

• US 7,472,106 B2
• Filed: 06/21/2002
• Issued: 12/30/2008
• Est. Priority Date: 06/22/2001
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Nakamura, Toshiyuki, Muneta, Yasuo
• Primary Examiner(s): Wong; Don
• Assistant Examiner(s): Black; Linh
• Application Number:
  US10/481,503
• Publication Number:
  US 20040210620A1
• Time in Patent Office: 2,384 Days
• Field of Search: 707 1-1041, 399 8- 9
• US Class Current: 1/1
• 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 2219/14012 Safety integrity level, safety integrated systems, SIL, SIS
• CPC Class Codes: G05B 2219/24137 Non volatile memory to store program on power loss
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A safety PLC 1 serving as a master and a safety slave 2 are connected through a safety network 3 to constitute a network system. The safety slave has non-safety information storing unit 26 for storing individual information and a state information of the connected safety device, the state information monitors a state of the operating safety device and a stored content is updated based on its monitored result. Then, when the non-safety information satisfying a fixed condition, at least the non-safety information satisfied the condition is transmitted to the safety PLC. That processing is performed by an MPU 23. Thus, unnecessary non-safety information is not transmitted.

Claims

1. A safety slave connectable to a safety network, the safety slave comprising:

a safety information transmitting function of transmitting safety information determining whether a safe state corresponding to safety of a human or a dangerous state corresponding to danger to a human exists, corresponding to a demand transmitted from a safety controller through the safety network;

non-safety information storing means for storing non-safety information about the safety slave;

storing means for storing a fixed condition for transmitting the non-safety information;

monitoring means for determining whether the non-safety information stored in the non-safety information storing means satisfies the condition or not;

determining means for determining a transmission timing based on a monitored result of the monitoring means, wherein said fixed condition is corresponding to a life expectancy of a safety device connected to said safety slave; and

a function of transmitting at least the non-safety information at said transmission timing when said monitoring means determines the non-safety information satisfies said fixed condition wherein transmission of the non-safety information is performed in one communication cycle based on the demand after safety slaves other than the safety slave finishes safety response, the safety slaves other than the safety slave being connected to devices other than the devices connected to the safety slave.

2. A safety network system comprising a safety controller and a safety slave according to claim 1, which are connected through a safety network, wherein information of the device output from the slave is transmitted to the controller.

3. The safety network system according to claim 2, wherein one communication cycle managed by the safety controller has a reception period for non-safety information after reception of a safety response from the safety slave.

4. The safety slave according to claim 1, wherein said fixed condition is further corresponding to at least one of an energized time of a safety device connected to said safety slave, a number of ON/OFF operations of relays in said safety slave and a number of retrying communication.