JP2003309610A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus by which the configuration of a communication circuit is simplified by the common connection of the output of each LSI to the input part of a line driver without connecting exterior hardware, and also the number of components is reduced. <P>SOLUTION: The communication apparatus includes each LSI comprising a data signal to the line driver, and a signal for controlling the output of the line driver. The data signal output part of the LSI is a tristate form, the signal for controlling the tristate output part is pulled-down by internal resistance, and clamped to a normal L level, and an H level is adopted as an output when the line driver is made to be active. Then an address is designated from a host station, so that the communication apparatus performs response. When the plurality of LSIs are mounted on the same board, the outputs of the LSIs are connected in common to the input part of the line driver. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device such as a servo drive device for transmitting and receiving various signals using a network or the like. The present invention relates to a communication device having a simplified configuration and a reduced number of components. 2. Description of the Related Art Generally, in a servo drive device for transmitting and receiving a signal using a network or the like, when there are a plurality of LSIs for inputting and outputting a signal, a circuit for transmitting the signal is formed by the same module. In many cases, they are collectively configured on a plurality of axes. In this case, in order to share software or components, circuits for sending signals from the LSI are configured by performing a logical OR operation on a part of the circuits while maintaining the single axis, thereby reducing costs. The company is reducing the number of parts by sharing line drivers and receivers. FIG. 3 shows a conventional circuit configuration in a case where the above-mentioned LSI is single and a single-axis circuit is used. Note that FIG.
In, the line driver and the line receiver are integrated and described as a line driver receiver 1. Here, 2 is an LSI (ASIC). [0005] Received data RXD as an input signal is input to an LSI (ASIC) 2 through a line driver receiver 1, and transmission data TXD as an output signal and the line driver receiver 1 are transmitted at the time of transmission.
Is output to the line driver receiver 1. When the signal DT / R goes high, the line driver receiver 1 becomes active, and the transmission data TXD is output to the right half-duplex transmission line via the line driver receiver 1. . On the other hand, FIG. 4 shows a conventional circuit configuration in a case where there are a plurality of LSIs and a multi-axis circuit is used. In this conventional circuit, the slave station LSI2
The transmission data TXD and the signal DT / R output from each LSI 2 are output to the line driver receiver via the logic circuits 3 to 7 as shown in FIG. In order to select the output of the LSI 2 specified by the upper station from the plurality of LSIs 2 and output the selected output to the line driver receiver 1, the target LSI 2 is selected by using the signal DT / R and the above-described logic circuit. Transmission data TXD
Is selected, the transmission data TXD from the LSI 2 is input to the line driver receiver 1, and the logical sum of DT / R is activated to activate the line driver receiver 1, and the transmission data TXD is transmitted to the right half-duplex transmission path. Output. [0010] However, in the above-described servo drive device, not only is the circuit itself for transmitting a signal from the LSI 2 complicated, but also a logic circuit or the like is used as a part of the circuit. There was an inconvenience that the number of parts was large. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and simplifies the configuration of a communication circuit without connecting external hardware to an input of a line driver for an output of an LSI. It is another object of the present invention to provide a communication device capable of reducing the number of components. In order to solve the above problems, the present invention provides an LS having a data signal to a line driver and a signal for controlling an output of the line driver.
I, the data signal output section of the LSI is in a tri-state form, and a signal for controlling the output section of the tri-state is internally pulled down by a resistor and clamped to a normal L level to activate the line driver. A communication device that responds by specifying an address from an upper station by outputting an H level when the LSI is mounted on the same board, and the output of the LSI is sent to a line driver. The common connection is made to the input section. An embodiment of the present invention will be described with reference to the drawings. The features of the present invention are as follows. FIG. 1 shows the individual L of one embodiment of the present invention.
It shows an output section of the SI, and a tri-state buffer is provided in each of the output sections of the transmission data TXD and the signal DT / R. Here, the tri-state means that the output of the digital circuit can take three states, that is, a high level, a low level, and other floating states, and is usually used in a data bus or the like. The output section of the signal DT / R is pulled down by a resistor, and the DT / R output is fixed at a low level except when the DT / Ri signal is at a high level. The tristate control described above is performed by the signal DT / Ri conventionally output directly from the LSI 2 as a DT / R signal. In the figure, a signal DT / Ri takes a binary state of a high level and a low level, and the output state of each tristate buffer is controlled to a floating state by setting the signal DT / Ri to a low level. be able to. That is, when the signal DT / Ri is at a low level, the transmission data TXD is in a floating state, and the signal DT / R is fixed at a low level by pulling down the floating state with a resistor in the figure. On the other hand, when the signal DT / Ri is at a high level, TXDi data is output as it is as the transmission data TXD. FIG. 2 shows a connection state between a plurality of LSIs and a line driver receiver in one embodiment of the present invention. In this embodiment, a case is shown where there are three LSIs 2 as slave stations. DT / Ri of LSI specified by upper station
The signal becomes high level and the TXD output of this LSI is TX
Di data is output as it is. The TD / Ri of the other LSIs 2 not specified by the upper station has a low level, and the respective TXD outputs are in a floating state. When these three TXD outputs are simply connected on a printed circuit board, LSI data specified by a higher-level station whose output is clearly determined becomes valid and is input to the line driver receiver 1. On the other hand, by simply connecting the DT / R on the printed circuit board, it becomes a wired OR of active high, outputs a high level, and activates the line driver. By configuring the output section of each LSI 2 as described above, all outputs from each LSI 2 can be simply wired common connection on a printed circuit board, and the transmission data output from each LSI 2 TXD
The signal DT / R does not need to be passed through a logic circuit or the like as in the related art. As described above, according to the present invention, the LSI 2 having the data signal to the line driver 1 and the signal for controlling the output of the line driver 1 is provided. In the form of a state, a signal for controlling the output section of the tri-state is internally pulled down by a resistor and clamped to a normal L level. This is a communication device that responds by specifying an address. When a plurality of LSIs 2 are mounted on the same board, the output of the LSI 2 is commonly connected to the input unit to the line driver 1. The configuration of the communication circuit without connecting external hardware to the input of the line driver to the input of the line driver And a communication device capable of reducing the number of parts can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration of an output unit of an LSI according to an embodiment of the present invention. FIG. 2 is a circuit configuration of an embodiment of the present invention in which the LSI has a plurality of communication circuits. Conventional circuit configuration having a single LSI and a single-axis communication circuit [FIG. 4] Conventional circuit configuration having a plurality of LSIs and a multi-axis communication circuit [Description of References] 1: Line driver receiver 2: LSI 3- 7: Logic circuit

Claims (1)

Claims: 1. An LS having a data signal to a line driver and a signal for controlling an output of the line driver.
I, the data signal output section of the LSI is in a tri-state form, and a signal for controlling the output section of the tri-state is internally pulled down by a resistor and clamped to a normal L level to activate the line driver. A communication device that responds by specifying an address from an upper station by outputting an H level when the LSI is mounted on the same board, and the output of the LSI is sent to a line driver. A communication device having a common connection to an input unit.