PROGRAMMABLE CONTROLLER

• US 20070282457A1
• Filed: 01/29/2007
• Published: 12/06/2007
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: ELAN Schaltelemente GmbH & Company, Jtekt Corporation (Toyota Motor Corporation)
• Inventors: Araki, Tsutomu, Kramer, Manfred, Nishi, Mitsushi
• Granted Patent: US 7,698,600 B2
• Time in Patent Office: Days
• US Class Current: 700/1
• CPC Class Codes: G05B 19/0428 Safety, monitoring G05B19/0423 takes precedence
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 2219/1181 Detection of I-O faults, shut down of I-O
• CPC Class Codes: G05B 2219/24047 Count certain number of errors, faults before delivering alarm, stop
• CPC Class Codes: G05B 2219/24049 Use of control bits
• CPC Class Codes: G05B 2219/25153 Checking communication
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/0763 by bit configuration check, e.g. of formats or tags
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 1/242 by comparing a transmitted test signal with a locally generated replica

Abstract

A programmable controller having self-diagnosis unit 60 (70) for self-diagnosis, wherein the self-diagnosis unit 60 (70) comprises data storage unit 61 (71) for storing data pertaining to an inspection unit for which the inspection is completed, and inspection start unit 62 (72) for starting the inspection from the next inspection unit of the inspection unit for which the inspection is already completed at the time before the power is turned on, when performing a self-diagnosis that occurs after the power is turned on, based on the data stored in the data storage unit 61 (71).

Claims

1. A safety control device for ensuring safety of an object to be controlled, comprising:

a communication unit that communicates a frame including a test bit string having correlation with a base bit string with another safety control device; and

a detection unit that compares the test bit string included in the frame received from the another safety control device with the base bit string, and detects a number of bit errors in the frame.

2. The safety control device according to claim 1, wherein at least a portion of the test bit string is a copied bit string copied from the base bit string.

3. The safety control device according to either one of claims 1 and 2, wherein at least a portion of the test bit string is a reversed bit string reversed from the base bit string.

4. The safety control device according to claim 1, wherein the test bit string includes:

a copied bit string copied from the base bit string; and

a reversed bit string reversed from the base bit string.

5. The safety control device according to any one of claims 1-4, wherein the base bit string and the test string vary with time while maintaining mutual correlation.

6. The safety control device according to any one of claims 1-5, wherein the frame includes the base bit string and the test bit string.

7. The safety control device according to any one of claims 1-6 further comprising a counting unit that increments a count value every configured cycle, wherein the base bit string indicates the count value.

8. The safety control device according to any one of claims 1-7 further comprising a storage unit that stores an accumulated value of the number of bit errors determined by the detection unit.

9. The safety control device according to claim 8 further comprising a safety-ensuring unit that performs, when the accumulated value within a set period of time exceeds an allowable value, a control for ensuring safety of the object to be controlled.

10. The safety control device according to claim 9, wherein the storage unit updates the accumulated value every the set period of time.

11. A safety control system comprising:

a plurality of safety control devices for ensuring safety of objects to be controlled; and

a communication line that connects the safety control devices with each other,

wherein each of the safety control devices includes;

a communication unit that communicates a frame including a test bit string having correlation with a base bit string with at least another one of the safety control devices through the communication line; and

a detection unit that compares the test bit string included in the frame received from the another safety control device with the base bit string, and determines a number of bit errors in the frame.

12. A method for detecting an error in communication between safety control devices that ensures safety of an object to be controlled, the method comprising:

receiving by one of the safety control devices from another of the safety control devices a frame including a test bit string having correlation with a base bit string; and

detecting a number of bit errors in the frame by comparing the test bit string included in the frame received from the another safety control device with the base bit string.

13. A method for detecting an error in communication between safety control devices that ensures safety of an object to be controlled, the method comprising:

generating, in a first safety control device, a frame including a test bit string having correlation with a base bit string;

transmitting the frame generated from the first safety control device to a second safety control device; and

detecting, in the second safety control device, a number of bit errors in the frame by comparing the base bit string with the test bit string included in the frame.