Electrical computers and digital processing systems: multicomput – Remote data accessing
Reexamination Certificate
1999-10-13
2001-02-27
Geckil, Mehmet B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Remote data accessing
C709S224000
Reexamination Certificate
active
06195690
ABSTRACT:
FIELD OF THE INVENTION
The present invention is in the field of data acquisition systems which measure and control electrical signals. More particularly, the invention is in the field of peripheral equipment for attachment to a computer system, e.g. a personal computer or workstation, whereby the computer and peripheral equipment may be used for data acquisition.
BACKGROUND OF THE INVENTION
The personal computer has proved to be a boon to the field of data acquisition. A personal computer is a general purpose device which may be configured by software programs and by plug-in peripheral equipment to perform a wide variety of special purpose tasks, including data reduction or computation, data acquisition and control. In the particular area of data acquisition, peripheral devices for performing measurements of physical phenomena and converting such measurements to digital signals conventionally are attached to a personal computer through an expansion bus. Messages are transmitted through the expansion bus to issue commands to instruments and to receive data back in return.
One conventional architecture for data acquisition systems includes a computer which communicates over the IEEE-488 bus with one or more processor controlled measurement instruments. The measurement instruments may include such complex devices as spectrum analyzers, as well as simpler devices, such as volt meters. However, each instrument includes a processor for communicating over the IEEE-488 bus and for controlling the instrument. Each instrument is treated in such a system as an intelligent peripheral which executes its own measurement program as directed through communication over the IEEE-488 with the computer. Processors may include microprocessors, microcontrollers, digital signal processors, etc. As a result, the instruments are expensive, consume relatively large amounts of electrical power, are designed for special measurement functions and are complex to program. Each instrument includes a processor as well as associated supporting logic and clocking circuits. The timing of communications over the bus is independent of the timing of measurements (i.e. the communications and measurement processes are asynchronous), thus increasing the exposure of sensitive instruments to digitally created noise from the bus. Therefore, special precautions must be taken in the design of such instruments to avoid electrical noise problems which could affect the measurements produced.
Another conventional approach to data acquisition systems is to attach a general purpose measurement module to a personal computer through an RS-232 or RS-422 serial port. Although such devices tend to be far less sophisticated than IEEE-488 bus based systems, the approach is substantially similar. Each measurement device has a processor within the device, for controlling the measurement components and processing commands and data to be sent or received through the RS-232 or RS-422 serial port. Measurement timing and communication functions are all controlled by the processor within each measurement device. Communication with the personal computer is achieved through the RS-232 or RS-422 serial port.
When a multiwire cable includes a signal wire carrying a signal that quickly transitions from one voltage level to another (e.g. a digital signal), a spike will inductively couple to all other wires in the cable, at each transition. In the case of a digital signal switching between 0V and 5V, 10 mV to 500 mV spikes may appear on the other signals in the cable. This means that the 10 mV to 500 mV spike is added to the other signals, and results in an error equal to the magnitude of the coupled spike. This is called cable cross-talk. Cable cross-talk may be seen in a conventional data acquisition system by grounding the most sensitive input to such a conventional data acquisition system at the sensor, far from the computer. The output of the grounded sensor should then be digitized, and viewed. The spikes discussed above will be seen in the signal viewed. This noise is added to the sensor signal even when it is not grounded, and therefore determines the maximum possible accuracy of the conventional system that has one multi-signal connector, e.g. a standard DB-25 connector, through which multiple I/O signals pass. In addition to cable cross-talk, noise can originate from ground loops, background electromagnetic fields, or the electromagnetic fields and ground noise injection generated by millions of simultaneously switching transistors inside the computer at MHZ rates. This problem of cable cross-talk affects many conventional systems because they route one or more analog and digital signals in the same cable. It should be noted that analog signals characterized by fast transitions can also cause cross-talk and noise to appear in other signals in a cable carrying such signals.
Many conventional systems suffer from one or more of the problems described above.
SUMMARY OF THE INVENTION
The present invention includes aspects which solve the various problems of the prior art indicated above, as well as other problems with conventional systems that would be evident to those skilled in this art, including but not limited to reducing cost and noise of highly accurate data acquisition systems.
In accordance with one aspect of the invention, there is provided a network based data acquisition system, comprising: a host computer having an expansion bus executing a software program to collect measurements from measurement components; a network controller subsystem in communication with the host computer through the expansion bus, the network controller having a controller synchronous serial network I/O port, the network controller including a processor executing a software program to generate control signals at the controller synchronous serial network I/O port that synchronously control the measurement components, responsive to the software program executed by the host computer; and a network device in communication with the controller synchronous serial network I/O port through a first device network I/O port, at least one component controlled through the first device network I/O port by the control signals generated by the network controller. As will be seen, the expansion bus can be a Peripheral Component Interconnect (PCI) bus, and Industry Standard Architecture (ISA) bus, a PCMCIA (PC card) bus, a NUBUS, Ethernet, Universal Serial Bus (USB) or FireWire. Generating control signals at the controller synchronous serial network I/O port at times of events controlled is sometimes referred to as real-time control or synchronous control because the control signals are made to occur at the actual time at which the event indicated by the control signals is intended to occur. Such real-time control or synchronous control is to be distinguished from the form of non-real-time control or asynchronous control where a control signal transmitted to a controlled device merely acts as a command which may be acted upon by the device at a later point in time.
In accordance with another aspect of the invention, there is provided an instrumentation system comprising an instrumentation control subsystem and a measurement subsystem including measurement components. Further in accordance with this aspect of the invention, the control subsystem and the measurement subsystem are interconnected by an instrumentation bus having: in the instrumentation control subsystem a communication device having an output carrying a control signals communicated to the measurement subsystem to synchronously control the measurement components; and in the measurement subsystem a communication device having an input which receives the control signal which synchronously controls the measurement component.
Finally, in accordance with yet another aspect of the invention, there is a method of controlling measurement instruments comprising the steps of: interconnecting a control system with a measurement system through a digital bus; controlling the measurement system through a series of signals sent
Geckil Mehmet B.
GW Instruments, Inc.
Wolf Greenfield & Sacks P.C.
LandOfFree
Network based data acquisition system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Network based data acquisition system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Network based data acquisition system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2582174