US 4,546,467 A · Monitor for transmission line

Abstract

A monitoring device for monitoring the status of communication units connected to a common transmission medium. The monitoring device sequentially addresses each communication unit and transmits to the addressed unit an inquiry frame which includes in addition to the destination address, a source address field and a control information field. The addressed communication unit, if operating responds with a reply frame including the destination address of the monitor, its address, and a status information field. The received status information is compared with a previously received status information from the addressed control unit, and a primary fault is indicated when the compared informations do not coincide. A secondary fault is indicated if no reply frame is received from an addressed communication unit within a predetermined time from the transmission of the inquiry frame.

Claims5

Dependent claims

In a network system wherein at least one data communication unit and a transmission line monitoring device are interconnected by a common transmission line, the monitoring device comprising:

means for exchanging data with a specific data communication unit via the common transmission line;
means for receiving status information fed from said data communication unit;
storage means for storing the status information fed from said data communication unit and connected to the receiving means
comparator means for comparing said status information of the data communication unit stored in the storage means with new status information returned from the data communication unit;
display means for displaying the new status information in response to the result of comparison at the comparator means;
and
status information writing means for writing the new status information in the storage means in place of the previously stored status information after said new status information has been compared with the stored status information in said comparator means.

4 more elements

In a local communication network including at least one communication unit connected to a transmission medium, a monitoring device comprising:

processor means for composing an inquiry frame, said inquiry frame containing at least a destination address field identifying a particular one of said at least one communication unit, a source address field and a control information field;
means for transmitting the inquiry frame to said at least one communication unit;
means for receiving a reply frame from the particular one of said at least one communication unit identified by the inquiry frame, said reply frame containing at least a destination address field, a source address field and a status information field containing information on the status of the particular communication unit identified by the inquiry frame;
status information storage means for storing status information relative to the particular communication unit identified by the inquiry frame;
means for comparing the received status information with status information stored in said status information storage means;
means for displaying a fault condition when the received status information does not coincide with the stored status information;
and
means for replacing the stored status information with the received status information in said status information storage means when said received status information does not coincide with the stored status information.

5 more elements

Dependencies are inferred from the claim text.

Monitor for transmission line

Life of this patent

Monitor for transmission line

Life of this patent

Abstract

Claims5