Programmable logic controller

• US 9,058,294 B2
• Filed: 03/22/2011
• Issued: 06/16/2015
• Est. Priority Date: 03/22/2011
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kono, Takumi
• Primary Examiner(s): TRUONG, LOAN
• Application Number:
  US13/985,366
• Publication Number:
  US 20130326287A1
• Time in Patent Office: 1,547 Days
• US Class Current: 1/1
• CPC Class Codes: G05B 19/054 Input/output
• CPC Class Codes: G05B 2219/1109 Expansion, extension of I-O
• CPC Class Codes: G06F 11/0745 in an input/output transactions management context input/output processing in general G06F13/00
• CPC Class Codes: G06F 11/0751 Error or fault detection not based on redundancy power supply failures G06F1/30; network fault management H04L41/06
• CPC Class Codes: G06F 11/079 Root cause analysis, i.e. error or fault diagnosis in a hardware test environment G06F11/22; in a software test environment G06F11/36
• CPC Class Codes: G06F 11/14 Error detection or correction of the data by redundancy in operation G06F11/16 takes precedence

Abstract

A programmable logic controller of the invention comprises: a CPU unit; various kinds of units controlled by the CPU unit and coupled via common connectors, that is, input/output units, an end cover, a branch unit and an extension unit; an internal bus provided extending through the CPU unit and the various kinds of units to connect the CPU unit and the various kinds of units; and a bus I/F provided in each of the various kinds of units in common and holding anomaly detection data for detecting an anomaly in the internal bus. The CPU unit checks the anomaly detection data read out from the bus I/F of each of the various kinds of units, thereby to detect an anomaly place in the internal bus.

Claims

1. A programmable logic controller that includes a basic block and an extension block coupled to the basic block via an extension cable and has a baseless structure, comprising:

a CPU unit provided in the basic block;

various kinds of units controlled by the CPU unit and coupled via common connectors;

an internal bus provided extending through the CPU unit and the various kinds of units to connect the CPU unit and the various kinds of units; and

a branch unit that is one of the various kinds of units which makes the internal bus divide into some parts, one of which is connectable to the extension cable,

wherein the various kinds of units each comprise a bus interface holding anomaly detection data for detecting an anomaly in the internal bus,

the bus interface of the branch unit further holds extension-cable detachment information for detecting detachment of the extension cable, and

the CPU unit, when determining that a communication anomaly has occurred in the internal bus, detects a connection state of the extension cable from the extension-cable detachment information read out from the bus interface of the branch unit, and when determining that the connection of the extension cable is normal, checks the anomaly detection data read out from the bus interface of each of the various kinds of units, thereby to detect an anomaly place in the internal bus.

2. The programmable logic controller according to claim 1,

wherein the CPU unit determines whether or not an anomaly exists in the internal bus in the branch unit from the anomaly detection data read out from the bus interface of the branch unit before detecting the connection state of the extension cable.

3. The programmable logic controller according to claim 1, wherein when determining that a communication anomaly exists in the internal bus, the CPU unit identifies a unit of the various kinds of units or the extension cable in which the communication anomaly has occurred and makes an error notification.

4. The programmable logic controller according to claim 2, wherein when determining that a communication anomaly exists in the internal bus, the CPU unit identifies a unit of the various kinds of units or the extension cable in which the communication anomaly has occurred and makes an error notification.