JP2000196630A - Multiplex communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiplex communication system capable of reducing a communication format necessary to input output setting and quickly starting a device operation when the device is started. SOLUTION: A master station unit 101 transmits input output setting data to a slave station unit 102 through a communication line 105. The input output setting data consists of an output setting frame which has a bit width equal to the number of output ports and is composed of codes specifying either of two available modes, an input setting frame which has a bit width equal to the number of input ports and is composed of codes specifying either of two available modes and a communication pause period provided between the output and input setting frames. The slave station unit having received the input output setting data defines input-output ports of the bit width of the output setting frame as output ports among input-output ports, defines input output ports of the bit width of the input setting frame as input ports and decides either of two modes existing in inputs and output for every bit in accordance with the content of the output and input setting frames.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex communication device for performing multiplex communication between a master unit and a slave unit via a communication line, and more particularly to an operation signal of various switches and various actuators in a vehicle. The present invention relates to a multiplex communication device suitable for transmitting a drive signal and the like.

[0002]

2. Description of the Related Art To transmit operation signals of various switches and drive signals of various actuators in a vehicle or the like,
In the past, it was common to connect necessary parts with wiring. Recently, however, signal transmission is performed by performing multiplex communication between a master station unit and a slave station unit via a communication line. Equipment is beginning to be used. In such a multiplex communication device, a plurality of output ports (output drive signals to various actuators) and a plurality of input ports (input of switch operation signals, signals from sensors, etc.) are provided to one slave station unit. And input / output signals via respective output ports and input ports.

In the above configuration, it is necessary to set each input / output port for output or input in advance. In the past, it has been common practice to make hardware settings at each input / output port of each slave station unit. However, in the case of hardware setting, it is necessary to set hardware for each slave unit according to the position of each load and each switch connected to each input / output port. There has been a problem that it takes time to change.

[0004] In order to solve the above problems, the present applicant has
A multiplex communication apparatus for setting the input and output of each input / output port of each slave station unit by communication from the master station unit before starting a normal communication operation (when power is turned on, etc.) has already been filed (Japanese Patent Application No. 10-282222). Issue unpublished). In such an apparatus, the input / output setting data from the master station unit may be transmitted in a communication format as shown in FIG. 5, for example.

[0005] In FIG. 5, the communication format is SOM (Start Of Message) which is a code indicating the start of transmission,
Command frame COM (COMman
d), following an address frame ADR (ADdRess) indicating the address of the slave unit of the transmission destination, an output width setting frame indicating a bit width desired to be set as an output port among the input / output ports, and a mode setting frame specifying the mode of each port It has. In this mode setting frame, the high-side drive or pull-up resistor connection is designated by “1” and the low-side drive or pull-down resistor connection is designated by “0” (details will be described in the embodiments of the invention). Note that the AP (Address
(Parity) is the parity for the COM frame and the ADR frame, DP (Data Parity) is the parity for the Data frame, and EOM (End Of Message) is a code indicating the end of communication.

In FIG. 5, since it is assumed that the slave unit has an 8-bit input / output port (the total number of inputs and outputs is eight), the output width setting frame is used to represent 0-8. A necessary 4 bits and a mode setting frame are provided for a total of 8 bits, one bit for each port, and transmitted from the lower order. For example, when it is desired to output 3 bits and input the remaining 5 bits of the 8-bit input / output port, “3”, that is, 001 is set in the output width setting frame.
1 are transmitted from the lower order. If the output ports are set to low-side drive, low-side drive, and high-side drive in order from the bottom, and the input ports are set to pull-down, pull-up, pull-down, pull-up, and pull-up in order from the bottom, the mode setting frame Contains 0, 0,
The transmission is performed in the order of 1, 0, 1, 0, 1, 1.

The slave unit which has received the above signal sets the lower 3 bits to "1" and the rest to "0" based on the value "3" of the output width setting frame, and sets the value of the mode setting frame to the mode. Hold in a register. As a result, the 8-bit input / output port of the slave unit can be operated for output or input with a desired function, and thereafter, the load drive of the slave unit by the transmission data from the master unit is performed. Also, it is possible to notify the input state to the master station unit by the transmission data from the slave station unit. As can be seen from FIG. 5, the data length required for the input / output setting is 12 bits (4 + 8 = 12) per node of the slave unit having 8 bits input / output.

According to the multiplex communication device of the above-mentioned prior application, the setting of input and output of each input / output port can be arbitrarily changed by the program of the master station unit. Therefore, by using a board of the same configuration as a slave station unit and setting the program of the master station unit according to the organization of the load and switch connected to each slave station unit, arbitrary organization can be performed using the same board. In addition, the cost can be reduced because it is easy to change after assembly.

[0009]

In the multiplex communication apparatus according to the prior application filed by the applicant of the present invention, the input / output setting for setting the input / output port from the master unit to each slave unit is performed at the time of starting the apparatus. It is necessary to transmit data and write to the register of each slave station unit, but the data length required for input / output setting requires, for example, 12 bits in the case of a slave unit having 8-bit input / output. . Therefore, when the number of slave station units and the number of input / output ports increase, the time required for the input / output setting by communication increases, so that there is a problem that the time required for the initial setting at the time of starting the apparatus becomes longer.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above. It is an object of the present invention to shorten the communication format required for input / output settings, and to start the operation of the device immediately when the device is started. It is an object of the present invention to provide a multiplex communication device that can perform the multiplex communication.

[0011]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as described in the claims. That is, in the invention according to claim 1, a master station unit and a slave station unit having a plurality of input / output ports are connected via a communication line, and the master station unit outputs a drive signal output on the communication line. The slave unit receives and controls a load (e.g., a motor or a lamp) connected to the input / output port set as an output in the slave unit by the drive signal, and is set as an input in the slave unit. The slave station unit outputs a signal from a signal generating means (for example, a switch or a sensor) connected to the input / output port to a communication line, and the master station unit receives the signal.
The input / output of the slave station unit can be selected for input or output, and there are two modes for input and output, respectively. Before starting normal communication operation (for example, at power-on), By transmitting input / output setting data for input / output port setting from the master station unit to the slave station unit, each input / output port of the slave station unit is set to either input or output, and the input / output setting is performed. The data consists of an output setting frame having a bit width corresponding to the number of output ports and consisting of a code designating one of the two modes for each bit, and an output setting frame having a bit width corresponding to the number of input ports for each bit. An input setting frame consisting of a code designating one of the two modes, and a communication pause period provided between the output setting frame and the input setting frame The slave station unit that has received the input / output setting data sets the bit width of the output setting frame as an output port among the input / output ports, and sets the bit width of the input setting frame as the output port. An input port is configured so that one of the two modes existing in each of the input and output is determined for each bit in accordance with the output setting frame and the contents of the input setting frame.

With the above configuration, the total length of data including the output setting frame and the input setting frame is the same as the number of bits of the total number of input / output ports, and the communication suspension period for one bit is reduced. Since it is only added, the length of the input / output setting data can be significantly reduced as compared with the related art.

The two modes existing at the input port of the slave station unit are, for example, a pull-up resistor connection and a pull-down resistor connection.

The two modes present at the output port of the slave station unit are, for example, high-side drive and low-side drive.

[0015]

According to the present invention, the input / output setting can be performed in a short format, and the effect that the input / output setting at the time of starting the apparatus can be completed in a shorter time can be obtained.

[0016]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, a master station unit 1
01 and a plurality of slave units 102 to 104
5 is connected. Each of the slave station units 102 to 104 has a plurality (eight in this case) of input / output ports 119 to 126.
Motor 127, lamps 128-1
Loads such as 29 and signal generating means such as switches 130 to 134 are connected. Note that the above configuration exemplifies the case where the number of input / output ports is eight, and other numbers are of course possible. For example, if there are 16 input / output ports, 8
The bit may be changed to 16 bits. In some cases, a sensor is used instead of a switch.

Hereinafter, the slave unit will be described by taking the slave unit 102 as an example, but the basic configuration of each slave unit is the same. However, input and output settings of each input / output port can be set arbitrarily for each slave unit.
The slave station unit 102 includes a receiving circuit 106 for receiving data from the master station unit 101, a DDR (Data Direction Register) 110 for switching input / output ports 119 to 129 to input or output based on the received data, and a mode for determining a mode. Setting register 109, load ON /
An output data register 108 for determining OFF is provided, and input / output circuits 111 to 118 capable of selecting input, output and various modes are provided for each port.

Each of the above registers is initialized to all bits "0" once when the apparatus is started (when power is turned on). DDR1
As for the output of 10, “1” indicates the output designation, “0” indicates the input designation, and the port whose corresponding bit is “1” is N
The transistors 141 and 142 are both turned off by the operation of the OT gate 146, the NAND gate 137, and the AND gate 138, so that the pull-up resistor 143 and the pull-down resistor 144 are disconnected. Therefore, the port is designated for output. The ports that are “0” are NOT gate 145, NAND gate 135, and A
The output transistor 13 is operated by the function of the ND gate 136.
9 and 140 are prohibited. Therefore, the port is designated for input.

When the output of the mode setting register 109 is "1", the port specified by the DDR 110 is driven by the power supply side output transistor 139 by the operation of the NAND gate 135 and the AND gate 136 (the port side is driven by the power supply). Connected to a high potential)
Is selected, and when "0", low-side drive by the GND-side output transistor 1 side (the port side is grounded and the load side becomes high potential) is selected.

When the output of the mode setting register 109 is "1", the power supply side transistor 141 of the port specified by the DDR 110 is turned on by the operation of the NAND gate 137 and the AND gate 138.
Then, a pull-up resistor 143 is connected. When it is “0”, the GND-side transistor 142 is turned on, and the pull-down resistor 144 is connected. As described above, high-side driving or low-side driving, pull-up resistor connection, or pull-down resistor connection can be freely set according to the characteristics and use state of the load, switch, and the like.

The port whose output is designated by the DDR 110 performs a load drive in the mode designated by the mode setting register 109 in accordance with the load drive data from the master station unit 101 stored in the output data register 108. Further, the status of the port designated by the DDR 110 is transmitted to the master station unit 101 via the transmission circuit 107 as input data.

The transmission format at the time of input / output setting will be described below. FIG. 2 is a diagram showing an embodiment of a transmission format from the master station unit 101 at the time of input / output setting. In FIG. 2, the communication format is SOM (Start Of Message) which is a code indicating the start of transmission.
e), a command frame COM (COM indicating the type of data)
mand), an address frame ADR (ADdRess) indicating the address of the slave unit of the transmission destination, a COM frame and an ADR
AP (Address Parit) which is the parity for the frame
y), DP (Dat which is a parity for the Data frame)
a Parity), a code EOM (End Of Mes) indicating the end of communication
sage). Then, following the transmission start code SOM, the command frame COM, the destination address ADR, and the parity AP, an output setting frame and an input setting frame are transmitted. In addition, a communication suspension period (in FIG. 2, indicated as “pause”) is provided between the output setting frame and the input setting frame. During this communication suspension period, the communication line is set in the same state as when no data communication is performed. For example, in a device that sets the communication line to the GND level while data communication is not being performed, the communication pause period is also set to the GND level, and in a device that continuously emits a pulse having a specific amplitude, the same pulse is inserted as the communication pause period. I do. However, in such a multiplex communication device, if it is detected that there is no data on the communication line for a predetermined time, the reception is generally terminated. Must be shorter than the detection time or the number of pulses.

The output setting frame and the input setting frame in FIG. 2 are different from the conventional example shown in FIG. That is, the output setting frame has a bit width corresponding to the number of input / output ports to be designated for output, and each bit consists of a code for designating the mode of the output port, and the input setting frame should be designated for input. It has a bit width corresponding to the number of input / output ports, and each bit is composed of a code designating the mode of the input port.

Therefore, the lengths of the output setting frame and the input setting frame change (the entire length is constant) according to the number of bits for output and for input, and communication between the output setting frame and the input setting frame is performed. A pause will be entered. That is, the position of the communication suspension period is located on the boundary between output and input, and the end (DP) from the beginning of the format (immediately after the AP) according to the distribution of output and input of the input / output ports.
Until immediately before).

Each bit in the output setting frame is
The mode designation for the output port indicates that "1" indicates high-side drive and "0" indicates low-side drive. Each bit in the input setting frame indicates the mode designation for the input port, where "1" indicates a pull-up resistor connection and "0" indicates a pull-down resistor connection.

The operation will be described below. When the apparatus is started, the master station unit 101 is connected to each of the slave station units 102 to 10.
4, the input / output setting data is transmitted in the format shown in FIG. Pre-station unit 102 that has received this
Counts the number of bits from the start of the output setting frame until the communication suspension period is detected, and sets the DDR 110 based on the counted number. In the example of FIG. 2, since the bit width of the output setting frame is 3 bits, "1" is set in the lower 3 bits of the DDR 110 and "0" is set in the remaining bits, and the input / output port 119 of the slave unit 102 is set. To 126, the lower three bits (119 to 1)
21) is set for output, and the rest (122 to 126) are set for input.

Each bit in the output setting frame is
The mode designation for the output port indicates that "1" indicates high-side drive and "0" indicates low-side drive. For example, as shown in FIG. 1, when low-side driving, low-side driving, and high-side driving are performed in order from the lower order, 0, 0, and 1 are set in the lower order as shown in the output setting frame in FIG.

Each bit in the input setting frame is
A mode designation for an input port is shown, where "1" indicates a pull-up resistor connection and "0" indicates a pull-down resistor connection. For example, as shown in FIG. 1, when pull-down, pull-up, pull-down, pull-up, and pull-up are performed in order from the bottom, 0, 1, 0, 1,. It becomes 1. Slave unit 10
2 sets the received data of the output setting frame and the data of the input setting frame to the lower and upper bits of the mode setting register, respectively.

As described above, according to the communication format of FIG. 2, when setting for output and input as shown in FIG. 1, "0, 0, 1, pause, 0, 1, 0, 1" is performed. , 1 ”may be transmitted and received. That is, the total length of the data including the output setting frame and the input setting frame is only the same number of bits as the total number of input / output ports, and only a 1-bit communication suspension period is added thereto. Data length can be significantly reduced.
For example, in the case of a slave unit having 8-bit input / output as described above, one slave unit has 9 bits. On the other hand, in the case of the slave unit having the same 8-bit input / output in the conventional example shown in FIG. 5, 12 bits are required, and the input / output can be initialized in a shorter format in the present invention.

FIG. 3 is a diagram showing a specific example of the transmission format shown in FIG. 2, and shows an example applied to multiplex communication using a PWM code. In FIG. 3, data "1" and "0" are represented by the magnitude of the pulse width per bit,
When data is not output on the communication line, the communication line is set to the GND level. Therefore, the communication suspension period between the output setting frame and the input setting frame is also set to the GND level for one bit period. Parities AP and DP exemplify odd parity.

FIG. 4 is a diagram showing another specific example of the transmission format shown in FIG. 2, showing an example applied to multiplex communication using a clock superimposed code. In FIG. 4, data "1",
When “0” is indicated and data is not output on the communication line, a pulse having a third amplitude different from the data pulse is continuously transmitted. Therefore, the communication pause period between the output setting frame and the input setting frame is represented by a pulse having the third amplitude. Parities AP and DP exemplify odd parity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of a transmission format from a master station unit 101 at the time of input / output setting.

FIG. 3 is a diagram showing a specific example of the transmission format shown in FIG. 2, which is applied to multiplex communication using a PWM code.

FIG. 4 is a diagram showing another specific example of the transmission format shown in FIG. 2, which is applied to multiplex communication using a clock superimposition code.

FIG. 5 is a diagram showing an example of a communication format of input / output setting data in the prior art of the present invention.

[Explanation of symbols]

101: master station unit 102-10
4 slave unit 105 communication line 106 receiving circuit 107 transmitting circuit 108 output data register 109 mode setting register 110 DD
R 111-118 ... I / O circuit 119-12
6 ... I / O port 127 ... Motor 128-12
9 Lamp 130-134 Switch 135 NA
ND gate 136 ... AND gate 137 ... NA
ND gate 138 ... AND gate 139, 14
0: output transistor 141, 142 ... transistor 143 ... pull-up resistor 144 ... pull-down resistor 145, 14
6… NOT gate

Claims (3)

[Claims] A master unit and a slave unit having a plurality of input / output ports are connected via a communication line, and the slave unit receives a drive signal output from the master unit on the communication line. The load connected to the input / output port set to output in the slave station unit is controlled by the drive signal, and the signal generation means connected to the input / output port set to input in the slave station unit. In the multiplex communication apparatus in which the slave station unit outputs a signal on a communication line and the master station unit receives the signal, the input / output port of the slave station unit can select input or output, and There are two modes for input and output, respectively. Before starting normal communication operation, input / output for input / output port setting from the master station unit to the slave station unit. By transmitting setting data, each input / output port of the slave unit is set to either input or output. The input / output setting data has a bit width corresponding to the number of output ports, and the input / output setting data is set to 2 bits per bit. An output setting frame including a code specifying one of the two modes, an input setting frame including a code having a bit width corresponding to the number of input ports and specifying one of the two modes for each bit; And a communication suspension period provided between the output setting frame and the input setting frame, wherein the slave unit receiving the input / output setting data,
Among the input / output ports, the output setting frame has a bit width equivalent to the output port, the input setting frame has the bit width corresponding to the input port, and the input and output setting frames and the input setting frame have the same contents. A multiplex communication apparatus characterized in that one of the two modes present in each output is determined for each bit. 2. The multiplex communication apparatus according to claim 1, wherein the two modes present at the input ports of the slave station unit are a pull-up resistor connection and a pull-down resistor connection. 3. The multiplex communication apparatus according to claim 1, wherein said two modes present at an output port of said slave unit are a high-side drive and a low-side drive.