US 4,949,299 A · Industrial control communication network and method

Abstract

A network consists of a programmable controller coupled to several sensors by an interface circuit. A common communication protocol is used to exchange messages containing commands and data between the devices coupled to the network. A protocol message packet has a header with fields for a task command, sensor identification, device status information and error codes. The header contains the same fields whether the message packet is for the interface circuit or one of the sensors connected to it. The headers for message packets going to and from the programmable controller and the interface circuit also have the same fields although the contents of the fields may vary depending upon the direction of the message packet. The message packet may also contain several data blocks each specifying a separate operation for the sensor to perform.

Claims11

Dependent claims

In a communications network in which a computer gathers data from different sensor devices over a cable, the improvement comprising an interface circuit coupling a sensor device to the cable, said interface circuit including:

means for receiving a message packet from said computer, said packet containing a plurality of operation commands for the sensor;
means for storing the plurality sensor operation commands received by said means for receiving;
means for sequentially sending data from each stored sensor operation command to the sensor device;
means for storing data from the sensor device in response to each sensor operation command;
and
means for transmitting the response data to the computer.

3 more elements

In a communications network having a programmable controller coupled to the network and at least one sensor coupled to the network by an interface circuit;

a method for controlling the interface circuit and sensor comprising:
(a) transmitting over the network to the interface circuit a message packet which contains a return code field, a command field, a field for sensor status, a field for interface circuit status, a sequence number field and sensor number field;
(b) the interface circuit upon receipt of the message packet, examining the command field to determine if the command is for the interface circuit or a sensor coupled to the interface circuit;
(c) if the examined command is for the sensor, the interface circuit responds by sending an instruction to the sensor regarding a task specified in the command field;
(d) if the examined command is for the interface, the interface circuit responds by performing a task specified in the command field;
(e) thereafter the interface circuit gathering data from either itself or the sensor in response to the performance of the task;
(f) the interface circuit forming a reply message packet containing the gathered data and having a return code field, a command field, a sensor status field, an interface status field, a sequence number field, and a sensor number field;
and
(g) the interface circuit transmitting the reply message packet on the network.

6 more elements

Dependencies are inferred from the claim text.

Industrial control communication network and method

Life of this patent

Industrial control communication network and method

Life of this patent

Abstract

Claims11