Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus interface architecture
Reexamination Certificate
2001-06-28
2004-05-04
Myers, Paul R. (Department: 2111)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus interface architecture
C710S106000, C710S110000
Reexamination Certificate
active
06732217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control and supervisory signal transmission system, and in particular, to a control and supervisory signal transmission system wherein a parallel control signal from a controller is converted into a serial signal to transmit it to a remote device, serial-parallel conversion is performed in a controlled section of the remote device to drive the device, a parallel supervisory signal in a sensor section to detect the status of the device is converted into a serial signal to transmit it to the controller, serial-parallel conversion is performed on the serial signal to provide it to the controller, the control signal is superimposed on a clock signal, and the supervisory signal is superimposed on these signals.
2. Description of the Related Art
In the technical field of automatic control, it is widely practiced that a control signal is sent from a controller such as a sequence controller, programmable controller, or computer to a number of remote controlled devices (a motor, solenoid, electromagnetic valve, relay, thyristor, and lamp, for example) to drive and control them and a supervisory signal is transmitted from a sensor section to the controller to detect the status of devices (the on/off state of a switch such as a reed switch, micro-switch, and push button switch)
In such a technology, a number of lines such as a power supply line, control signal line, and ground wire are used for the interconnection between the controller and the controlled devices, and between the controller and the sensor section. Therefore a problem has arisen that wiring work becomes difficult, wiring space decreases, and wiring costs increases as packaging density increases because of the recent downsizing of the controlled devices.
There are two approach to solving the problem: a “signal serial-parallel conversion system” (Japanese Patent Application No. 62-229978) and a “serial transmission system of a parallel sensor section signal” (Japanese Patent Application No. 62-247245). According to these systems, wiring in a transmission system between a controller and a controlled device or between the controller and a sensor section can be accomplished with a smaller number of lines because one (one bit) control signal (or sensor signal) corresponding to each clock can be superimposed on a clock signal line including power supply.
According an invention, a “control and supervisory signal transmission method” (Japanese Patent Application No. 1-140826), fast bidirectional signal transmission between a controller and a controlled unit and between the controller and a sensor section can be achieved by a simple configuration by connecting an input unit and an output unit to a parent station and providing a clock signal superimposed on power supply onto a common data signal line from the parent station. That is, the number of lines and the cost of wiring can be reduced, the connection arrangement of units can be simplified, and addresses can be allocated to the units at will, allowing the addition and deletion of a unit to be performed freely at a desired location.
According to the prior-art configuration describe above, fast bidirectional signal transmission between the controller and the controlled unit and between the controller and the sensor section can be achieved. However, a signal (hereinafter called a “control signal”) from the controller to the controlled unit and a signal (hereinafter called a “supervisory signal”) from the sensor section to the controller cannot be transmitted at the same time because they are provided onto the common data signal line. That is, the control signal and supervisory signal can be transmitted only mutually exclusively and cannot be transmitted in two directions at the same time. Therefore a time period during which the control signal is transmitted over the common data signal line and a time period during which the supervisory signal is transmitted must be separately provided.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a control and supervisory signal transmission system, wherein a control signal and supervisory signal are superimposed on a clock signal, the control signal is a binary signal having a predetermined duty ratio, and the supervisory signal as an electric current signal is detected.
It is another object of the present invention to provide a control and supervisory signal transmission system that superimposes a multiplexed control and supervisory signal on a clock signal.
It is still another object of the present invention to provide a control and supervisory signal transmission system that superimposes a first control signal which is a binary signal having a predetermined duty ratio and a second control signal which is a voltage signal on a clock signal and superimposes a supervisory signal which is a electric current signal on those signals.
It is still another object of the present invention to provide a control and supervisory signal transmission system that superimposes a first control signal which is a binary signal having a predetermined duty ratio and a second control signal which is a voltage signal on a clock signal and superimposes a first supervisory signal which is a current signal and a second supervisory signal which is a frequency signal on those signals.
A common configuration of a control and supervisory signal transmission system of the present invention comprises a controller; a plurality of controlled devices each of which includes a controlled section and a sensor section to monitor the controlled section; a parent station connected to the controller and a data signal line common to the plurality of controlled devices; and a plurality of child stations associated with the plurality of controlled devices and connected to the data signal line and the associated controlled devices, in which a control signal from the controller is transmitted to the controlled section and a supervisory signal from the sensor section is transmitted to the controller over the data signal line.
In addition to the components of the common configuration described above, the parent station of a control and supervisory signal transmission system of the present invention comprises timing generation means to generate a predetermined timing signal in synchronization with a clock having predetermined periodicity, a parent station output section, and a parent station input section. The parent station output section converts under the control of the timing signal the control signal into a serial pulse voltage signal by changing the duty ratio between a period of a voltage level other than a predetermined power-supply voltage level and the subsequent period of the power-supply voltage level in every period of the clock according to the data value of the control data signal input from the controller, and provides the converted signal onto the data signal line. The parent station input section detects under the control of the timing signal a supervisory data signal superimposed on a serial pulse voltage signal transmitted over the data signal line, in every period of the clock, as the presence or absence of a current signal generated by contention between the supervisory data signal and the power-supply voltage on the rising edge of the power-supply voltage level to extract each data value of the serial supervisory data signal, converts it into a supervisory signal and inputs it into the controller. Each of the plurality of child stations comprises a child station output section and a child station input section. The child station output section determines the duty ratio between a period of voltage level different from the power-supply voltage level of a serial pulse voltage signal and the subsequent period of the power-supply voltage level to extract the data values of a control data signal and provides data in the data values that corresponds to the child station to the corresponding controlled section. The child station input section constructs under
Harmo-Link Corporation
McGlew and Tuttle , P.C.
Myers Paul R.
Phan Raymond N
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