JPH04368096A - Multiplex transmitter - Google Patents

Abstract

PURPOSE:To avoid interrupt by a terminal equipment in response to a momentary signal and to prevent malfunction or mis-notice by providing a cancel means cancelling a momentary signal inputted from a load to the terminal equipment. CONSTITUTION:A delay circuit 10 to which an output of an input interface 7 is connected consists of resistors R1, R2 and a capacitor C1 and consists of a discharge circuit to set a delay time and an output transistor (TR) Q1 turned off after the charge in the capacitor C1 of the discharge circuit is discharged. When no fault signal comes from a load monitored by a central controller, since an output transistor(TR) of a photocoupler PC is turned off, the capacitor C1 is charged via a resistor R3 and the Tr Q1 is turned on. When a fault signal is inputted from the load, an output TR of the photocoupler PC is turned on, the discharge of the capacitor C1 is started, the TR Q1 is turned off after a prescribed time and the fault signal is inputted to a control circuit 4.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a multiplex transmission device in which a plurality of terminal devices are connected to a central control device via signal lines, and the central control device controls and monitors the operation of loads via the terminal devices. It is.

0002

2. Description of the Related Art As shown in FIG. 3, this type of multiplex transmission device connects a plurality of terminal devices 2 having unique addresses to a central control device 1 via signal lines L. A transmission signal specifying the address is sent cyclically to each terminal device in sequence, each terminal device 2 is accessed individually to control the operation of the load 3, and when an interrupt occurs from the terminal device 2, central control is performed. The device 1 performs interrupt processing to identify the interrupt request terminal 2, causes the identified interrupt request terminal 2 to return the monitoring contents of the load 3, and the central control device 1 centrally monitors the operating state of the load 3. There is something to do.

FIG. 4 shows an example of a transmission signal transmitted between the central control device 1 and the terminal device 2 in this type of multiplex transmission device. As shown in FIG. 4(a), this transmission signal includes a start pulse ST indicating the start of signal transmission, mode data MD indicating the data transmission mode, address data AD indicating the address of the terminal device 2 to be accessed, and a load 3. Consisting of control data CD indicating control data to be controlled, error detection data CS such as checksum data, and a return standby signal WT that sets a return period for monitoring data from the terminal device 2, the pulse shown in FIG. It is time-division multiplexed and transmitted using a width-modulated bipolar (±24V) signal.

Furthermore, each terminal device 2 operates by rectifying and smoothing the transmission signal transmitted from the central control device 1 via the signal line L to create a power supply. When the data and the own unique address data match, the control data of the transmission signal is taken in and the load 3
Controls the operation of Further, the operating state of the load 3 is monitored by implementing the following interrupt processing. At this time, a dummy transmission signal in which the mode data MD is set to a dummy mode is constantly transmitted from the central control device 1. Then, the terminal device 2 transmits an interrupt signal to the terminal device 2 in synchronization with the start pulse ST of the transmission signal.
An interrupt is generated by sending a message from . When this interrupt occurs, the central control unit 1 specifies the interrupt requesting terminal 2.

[0005] When specifying an interrupt requesting terminal 2, first, interrupt address polling is performed in which the central control unit 1 transmits the upper bits of address data and accesses a predetermined number of multiple terminals 2 at once as a group. mode transmission signal is transmitted, and the terminal device 2 is accessed block by block. Then, the lower bits of the address data are sent back from the interrupt request terminal 2. The central control unit 1 receiving the lower bits specifies the address of the interrupt requesting terminal 2 by combining the upper bits and the lower bits.

[0006] When the interrupt request terminal 2 is specified in this way, the central control unit 1 transmits a transmission signal of the individual access mode to the interrupt request terminal 2, and the specified interrupt request terminal 2 access individually and send back monitoring data. When the monitoring data is received by the central controller 1, the central controller 1 transmits a response mode transmission signal to the interrupt request terminal 2, stops transmitting the interrupt request signal, and interrupts the interrupt request. Finish the loading process.

In order to identify the interrupt requesting terminal 2 even faster, it is preferable to adopt the interrupt processing method proposed in Japanese Patent Publication No. 1-41075 or Japanese Patent Application No. 2-65010.

[0008]

By the way, when the load 3 is a fan unit or the like, for example, the above interrupt processing may be used to monitor a failure of the load 3. However, in conventional multiplex transmission equipment, when receiving a failure signal from load 3, terminal device 2 immediately interrupts, so for example, a momentary noise or signal from load 3 is input to terminal device 2. When such noise occurs, an interrupt is issued to the central control unit 1 in response to such noise, which causes problems such as the entire apparatus malfunctioning or generating false alarms.

The present invention has been made in view of the above points, and its purpose is to provide a multiplex transmission device that does not cause malfunctions or false alarms due to momentary noise or signals from the load. .

0010

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a terminal device with canceling means for canceling instantaneous signals input from a load.

[0011]

[Operation] By configuring the present invention as described above,
This prevents the terminal from issuing an interrupt in response to an instantaneous signal, thereby preventing malfunctions and false alarms.

0012

Embodiment FIGS. 1 and 2 show an embodiment of the present invention. As shown in FIG. 1, the terminal device 2 of this embodiment includes an output interface 6 that outputs a control signal for controlling the load 3;
An input interface 7 that inputs a monitoring signal for monitoring the operating state of the load 3, a transmission interface 5 that inputs and outputs transmission signals between the central control device 1, an address switch 8 that sets an address, and a transmission interface 5. It is formed of a dedicated LSI, etc. that performs signal processing such as controlling the operation of the load 3 in accordance with the control data CD that follows the address data AD when the address of the transmission signal received by the controller matches its own address. The control section 4 is composed of a CPU, a peripheral circuit 9 such as an oscillator for the control section 4, and a delay circuit 10 as a canceling means for delaying the output of the input interface 7.

Delay circuit 10 and input interface 7
A specific circuit is shown in Fig. 2. Here, the output of the input interface 7 is insulated and connected to the delay circuit 10 via a photocoupler PC. The delay circuit 10 includes a resistor R1
, R2 and a capacitor C1 to set the delay time, and an output transistor Q1 that turns off after the charge in the capacitor C1 of this discharge circuit is discharged.
It is made up of.

Now, when there is no failure signal from load 3, the output transistor of photocoupler PC is off, so capacitor C1 is charged via resistor R3,
Transistor Q1 is in the on state. And load 3
When a failure signal is input from the photocoupler PC, the output transistor of the photocoupler PC is turned on, discharging of the capacitor C1 is started, and after a certain period of time, the transistor Q1 is turned off, and the failure signal is input to the control circuit 4. Note that, for example, if the load 3 is a fan unit or the like, the delay time may be set to about 2 seconds.

When the delay circuit 10 is provided in the terminal device 2 in this way, even if an instantaneous noise or signal other than a failure signal is input, the voltage across the capacitor C1 will be lower than the voltage across the transistor Q1.
Since the voltage does not decrease until the voltage is turned off, it is possible to prevent an erroneous failure signal from being input to the control unit 4. Therefore, it is possible to prevent the terminal device 2 from interrupting the central control device 1 due to instantaneous noise or signals, thereby preventing malfunctions or false alarms.

Note that the interrupt processing performed by the central control device 1 to detect a failure of the load 3 is performed in the same manner as described in the section of the prior art.

[0017]

[Effects of the Invention] As described above, in the present invention, since the terminal device is provided with a canceling means for canceling the instantaneous signal input from the load, the terminal device can issue an interrupt in response to the instantaneous signal. This prevents malfunctions and false alarms from occurring.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a terminal device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of the delay circuit same as the above.

FIG. 3 is a system configuration diagram of a multiplex transmission device.

FIG. 4(a) is a signal format of a transmission signal. (b) is a signal waveform diagram same as the above.

[Explanation of symbols]

1 Central control device 2 Terminal 3 Load 10 Delay circuit L Signal line

Claims (1)

[Claims] Claim 1: A plurality of terminal devices having unique addresses are connected to a central control device via signal lines, and a transmission signal specifying the address is sequentially and cyclically sent from the central control device to each terminal device. The terminals are accessed individually to control the load operation, and when an interrupt is received from a terminal, the central control unit performs interrupt processing to identify the interrupt requesting terminal, and the identified interrupt request is processed. In a multiplex transmission device in which the load monitoring contents are sent back from the terminal device and a central control device centrally monitors the operating status of the load, the terminal device is provided with a canceling means for canceling the instantaneous signal input from the load. A multiplex transmission device characterized by: