INDUSTRIAL CONTROL COMMUNCATION NETWORK AND METHOD

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.