The present invention relates to system control, and more particularly, to methods and systems for diagnosing a network having smart or regulated devices in communication with the network.
Smart Distributed System (SDS) is a network technology developed by Honeywell which is a distributed network having interconnected intelligent, regulated and/or controllable devices. Intelligent devices in this context refers to, for example, devices having controllers, microcontrollers or like devices typically with volatile or non-volatile memory retention capabilities. Without limitation, examples of such devices include a sensor means (such as, for example, a photoelectric sensor, electromechanical sensor or a means for controlling an output signal such as a transistor or triactor) adapted to communicate with a system or computer network. While SDS technology has many applications, it was originally designed to simplify network control of automated systems and decrease the complexity of industrial automation. A typical SDS network can include a host controller (such as a controller, microcontroller, processor, computer or like device) in communication with bus structure or architecture, the bus typically comprising a plurality of wires. For example, the bus may comprise a plurality of wires 100a as seen in FIG. 1, two of which are coupled between devices or sensors and two which carry the network communication signals. In turn, each device is able to communicate over the network with other devices coupled to the network and the host controller as required for the process being controlled. While SDS systems are generally accurate, fast and efficient communication between all devices on the SDS network, one of the problems associated with the technology is its limited diagnostic features.
In most controlled processes, one or more sensors are coupled to a controllable apparatus (such as, for example, a material handling conveyor). The type of sensors employed vary depending on the apparatus being controlled, but could include a limit switch, a photoelectric switch or discrete devices. As technology advanced, so has the ability to communicate between the various controlled processes and devices. Thus, while decades ago a sensor could only be controlled to turn off or on (e.g., set/reset, high/low or like state settings), in today""s technology, a device can also communicate with other devices to communicate data relating to the device (such as, for example, the device""s health, the status of the process being sensed, etc.). Further, sensors such as those employed by the SDS technology are typically in communication with microcontrollers having non-volatile or volatile memory, all housed within the same housing or sensor package. As such, network technologies such as the SDS technology have allowed operators not only to control the sensors but also communicate with or configure the sensors through a network. In this regard, communication of information between sensors and the host controller can include communicating diagnostic information between the sensors and the network because the network is not limited to a single bit or a single wire, and further, because such communication can be of asynchronous or synchronous design. This is an important aspect of network design because an operator should be provided with early indications that a device or sensor is malfunctioning or has the potential to malfunction which may result in system failure and/or injury to humans. In the prior art, when one device or sensor malfunctioned, it was difficult to locate which sensor or device malfunctioned or where a problem originated. Moreover, a malfunctioning sensor or device might affect other sensors or devices in the network, thereby jeopardizing the proper completion of the process being monitored. Early determination of system problems or potential failures will allow the operator to take corrective action as deemed necessary to maintain proper system continuation.
For example, in photoelectric sensor technology, it is known that some photoelectric sensors operate by transmitting a beam of light from a source (usually infrared, polarized or coded) and receiving the beam""s reflection. Other such sensors seek reflections from the object being sensed. In any event, all such sensors emit light and seek to receive the emitted light. However, in operation, the lens in such sensors may get dirty or contaminated from a variety of sources, including dust, fingerprints or other debris found in the operating environment. When such sensors fail to detect the transmitted light, the sensors may be programmed to increase the amount of light signal transmitted. However, the power to transmit the light in such sensors can only be increased to a certain level to maintain operation (known as the marginal gain). When the sensor can no longer compensate beyond the marginal gain, the sensing function will likely be lost. The diagnostics built in to the SDS technology handles these situations by allowing the sensor to transmit information over the network to the host controller that it is nearing or at the marginal gain, thereby alerting the operator to take corrective action. However, when the network is down or malfunctioning, such information could not be transmitted to the host controller to notify the operator of the potential problem, thereby making diagnosing the problem difficult. In brief, while diagnostic tools existed at the device (e.g., sensor) level, such diagnostic tools did not exist at the network level.
Controller Area Network (CAN) technology is a technology originally developed to work in the automotive industry, however, it has also found application in other areas. The CAN technology is now found embedded within microcontrollers such as those manufactured by Motorola or Intel. Such CAN-based microcontrollers provide a robust communications capability designed for reliable operation even in environments which may have high levels of potential electrical interference. One of the benefits of the CAN technology is that it reduced the amount of wiring required between controllable devices (such as sensors), which resulted in cost savings. One of the other advantages of the CAN technology is that it incorporates error detection and confinement features into the microcontroller which ensure data integrity at the bit level and at the message level. The main purpose of CAN""s error detection function is to survive temporary communications errors which may be caused by spurious external condition, voltage spikes, etc. as well as permanent failures caused by bad connections, faulty cables, defective transmitters or receivers, or long lasting external disturbances.
What is needed is a CAN-based method for diagnosing potential failures on controllable devices within a network. Methods and systems such as those disclosed in the present invention would provide lower initial and recurring costs and further provide greater safety to operators who work with the controlled process or are in the vicinity of the controlled process.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention, and is not intended to be a full description. A full appreciation of the various aspects of the invention can only be gained by taking the entire specification, claims, drawings, and abstract as a whole.
Several embodiments of the present invention are disclosed for one or more methods for diagnosing potential or impending failures on one or more controllable devices within a network. In one embodiment, the present invention is a network having at least one controllable CAN-based sensor device having a microcontroller. Preferably, the network is a SDS-based network. In this embodiment, each microcontroller communicates with the computer, generating and storing a value in at least one counter when a successful message is transmitted to the computer. When a unsuccessful message is detected by the microcontroller, a counter generates and stores a second or decremental value in the counter. When a counter reaches a marginal critical value, a message is transmitted to the computer while maintaining the microcontroller""s communication with the network. When a counter reaches a critical value, the microcontroller enters a bus off mode and disconnects the sensor device, and thus the microcontroller, from the network.
In another embodiment, the present invention allows each microcontroller to generate and store power cycle information in at least one counter. The information may include the total cumulative number of power cycles, power cycles since last reset, total power-on time and power on time since last reset. The computer communicating with each microcontroller can obtain this information to generate maintenance or operational alerts or notifications to the network operator.
Another embodiment of the present invention is directed towards those microcontrollers controlling a visual indication means (such as a light emitting diode). The microcontroller is configured to control the LED to generate at least one predetermined blink pattern corresponding to either the network communication health or the attached sensing element""s operation.
The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention or can be learned by practice of the present invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the spirit and scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow.