Networked facilities management system with optical coupling of local network devices
First Claim
1. A computerized node controlling at least one slave device connected to a slave device bus having a pair of signal lines, the computerized node communicating with the slave devices over the slave device bus and being optically isolated from the slave device bus, the node having a mode output for providing a mode select signal, a transmit output and a receive input, the node comprising:
- a transmit optical isolator connected between the transmit output of the node and a line driver connected to the pair of signal lines;
a receive optical isolator connected between the receive input of the node and a line receiver connected to the pair of signal lines; and
a mode optical isolator having a mode input coupled to the mode output, the mode optical isolator activating at least one of the line driver or the line receiver in response to the mode select signal, the mode select signal being indicative of a transmit mode or a receive mode, the pair of signal lines receiving signals from the slave device bus in the receive mode and transmitting signals to the slave device bus in the transmit mode.
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Accused Products
Abstract
A networked system having a wide variety of applications and particularly applicable to facilities management systems has multiple levels of software in processing nodes. The levels include a "features" processing level which communicates requests for data to a software object level containing databases of processes and attributes and database managers. The database managers in the software object level operate to provide data to the high level features in the same format. The software object level communicates with a hardware object level which also contains databases and database managers to mask differences between operational hardware units. By categorizing operational units by type, additional units of a known type can be added with only low level hardware object database changes. Adding units of a new type is facilitated by software changes confined to the lower level hardware and software objects, avoiding software changes at high level features. Individual software objects are tailored for typical types of inputs and output devices encountered by facilities management systems. Universal drive circuitry also provides applicability to a broad range of devices. An optical isolator is connected between signal line outputs from a node and a line driver connected to a pair of lines on a bus. Similarly, an optical isolator is connected between signal line receiving inputs and a line receiver. The signal lines can be biased to predetermined levels to reduce node sensitivity to noise.
154 Citations
20 Claims
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1. A computerized node controlling at least one slave device connected to a slave device bus having a pair of signal lines, the computerized node communicating with the slave devices over the slave device bus and being optically isolated from the slave device bus, the node having a mode output for providing a mode select signal, a transmit output and a receive input, the node comprising:
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a transmit optical isolator connected between the transmit output of the node and a line driver connected to the pair of signal lines; a receive optical isolator connected between the receive input of the node and a line receiver connected to the pair of signal lines; and a mode optical isolator having a mode input coupled to the mode output, the mode optical isolator activating at least one of the line driver or the line receiver in response to the mode select signal, the mode select signal being indicative of a transmit mode or a receive mode, the pair of signal lines receiving signals from the slave device bus in the receive mode and transmitting signals to the slave device bus in the transmit mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of reducing sensitivity of a computerized node to noise induced on a bus connected between the node and at least one slave device controlled by the node, the node having a transmit output, mode select output, and a receive input, the method comprising the steps of:
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connecting a transmit optical isolator between the transmit output of the node and a line driver connected to a pair of signal lines of the bus; connecting a receive optical isolator between the receive input of the node and a line receiver connected to the pair of signal lines of the bus; connecting a mode optical isolator between the mode select output and the line receiver and the line driver; and in response to a mode select signal at the mode select output from the node, activating at least one of the line receiver and the line driver with the mode optical isolator, the mode select signal being indicative of a transmit mode or a receive mode, the pair of signal lines receiving transmit signals from the node in the transmit mode and the pair of signal lines providing receive signals to the node in the receive mode. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification