Single transmission line interrogated multiple channel data acquisition system
First Claim
1. A single transmission line interrogated multiple channel data acquisition system, comprising:
- a master interrogating station means for generating and transmitting a repeating interrogating signal including individual digital address codes for separately addressing a plurality of data channels and receiving quantitative data valves corresponding to a measured value from each separately addressed channel on a time shared basis;
a plurality of remote station/sensor means corresponding to said plurality of data channels, each remote station/sensor means including means for generating its own digital address code and comparing it with each address code transmitted by said master interrogating station, generating a transmit command signal when the transmittal address matches the address generated by said remote station/sensor, and a measuring and transmitting circuit means responsive to said transmit command signal for measuring and transmitting the corresponding channel quantitative data value in the form of a pulse position coded signal, said measuring and transmitting circuit means including a charge storage means for receiving and storing a charge proportional to said quantitative data value being measured and switching means for subsequently generating said pulse position coded signal at an output thereof corresponding to said stored charge;
a single transmission line coupled between said master interrogating station and each of said plurality of remote station/sensor means in parallel for transmitting said address codes to each of said plurality of remote station/sensor means and said pulse position coded signals from the output of each one of said plurality of remote station/sensor measuring and transmitting circuit means to said master interrogating station; and
a termination diode connected at the remote end of said transmission line.
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Abstract
A single transmission line interrogated multiple channel data acquisition system is provided in which a plurality of remote station/sensor circuits each monitors a specific process variable and each transmits measurement values over a single transmission line to a master interrogating station when addressed by said master interrogating station. Typically, as many as 330 remote stations may be parallel connected to the transmission line which may exceed 7,000 feet. The interrogation rate is typically 330 stations/second. The master interrogating station samples each station according to a shared, charging transmit-receive cycle. All remote station address signals, all data signals from the remote stations/sensors and all power for all of the remote station/sensors are transmitted via a single continuous terminated coaxial cable. A means is provided for periodically and remotely calibrating all remote sensors for zero and span. A provision is available to remotely disconnect any selected sensor station from the main transmission line.
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Citations
5 Claims
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1. A single transmission line interrogated multiple channel data acquisition system, comprising:
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a master interrogating station means for generating and transmitting a repeating interrogating signal including individual digital address codes for separately addressing a plurality of data channels and receiving quantitative data valves corresponding to a measured value from each separately addressed channel on a time shared basis; a plurality of remote station/sensor means corresponding to said plurality of data channels, each remote station/sensor means including means for generating its own digital address code and comparing it with each address code transmitted by said master interrogating station, generating a transmit command signal when the transmittal address matches the address generated by said remote station/sensor, and a measuring and transmitting circuit means responsive to said transmit command signal for measuring and transmitting the corresponding channel quantitative data value in the form of a pulse position coded signal, said measuring and transmitting circuit means including a charge storage means for receiving and storing a charge proportional to said quantitative data value being measured and switching means for subsequently generating said pulse position coded signal at an output thereof corresponding to said stored charge; a single transmission line coupled between said master interrogating station and each of said plurality of remote station/sensor means in parallel for transmitting said address codes to each of said plurality of remote station/sensor means and said pulse position coded signals from the output of each one of said plurality of remote station/sensor measuring and transmitting circuit means to said master interrogating station; and a termination diode connected at the remote end of said transmission line. - View Dependent Claims (2, 3, 4, 5)
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Specification