JPH03216039A - Communication system for multiple terminal devices - Google Patents

Abstract

PURPOSE:To allow the system to cope flexibly with the case such that terminal equipment is tentatively removed from the system by providing a circuit energizing a signal line through which a signal is sent from the terminal equipment to a host computer to a prescribed level to a repeater. CONSTITUTION:A host computer 1 transits a succeeding processing as expiration of time when terminal equipment 5 does not execute the transmission or reply for a prescribed time even in the case of reaching the transmission or response. Moreover, a transmission line for a signal sent from terminal equipment 5 to the host computer 1 connects to a termination resistor 44 of a repeater 3 or a pull-up resistor 46. Since the terminal equipment 5 is energized to a prescribed level even when the terminal equipment 5 is removed due to a fault or adjustment or the like, the job is attained by having only to remove a cable connecting to an input/output circuit of the terminal equipment and no effect is given to other devices.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication system, and more specifically to a communication system for a plurality of terminal devices that communicates parallel data with a plurality of terminal devices via a relay device.

For example, GP-IB is an interface standard for connecting multiple data devices and exchanging data in parallel.
(IEEE-488+ and SCSI If ANSIX3.
There is 131-19861.

GP-18 is an interface standard developed for connecting computers and measuring instruments, and specifies the physical shape, bin arrangement, electrical characteristics, etc. of the connector. G.P.
-IB can connect up to 15 devices in parallel and has 8 bidirectional data lines, 3 handshake bars and 5
I have a book management bus. In GP-IB, there are three basic interface functions: talker, listener, and controller, and each connected device has at least one of these functions.

The toe force has the function of outputting data, the listener has the function of inputting data, and the controller has the function of specifying the talker and listener. In GP-IB, a female connector is provided on the device side, and both ends of a cable connected to this are connectors in which a male type and a female type are placed back to back.

When connecting a plurality of devices in GP-IB, one end 1 of the cable connected to the female connector of the example device is further connected to one end of the cable connected to another device. As a result, an electrically bus-type network is formed.

SCSI is a bus-type interface using parallel transmission for connecting small computers and peripheral devices, and defines the physical shape and logical specifications. S.C.
The SI physical interface consists of nine bidirectional data paths and nine control signals. In SCSI, the concepts of initiator and target are introduced.

Here, the inishek is a host that issues commands to instruct the target to perform operations. Also, the target is
It becomes a controller that receives commands from the inishek and actually implements the functions. Up to eight hosts and controllers can be connected to one SCSI bus. Up to 8 peripheral devices can be connected in a daisy chain manner to one controller, so up to 64 peripheral devices can be connected.

However, in these GP-IB standards or SCSI standards, the transmitting side and the receiving side exchange signals such as communication start and response by handshaking. For this reason,
When specifying a target device by controller or inishake, the specified device must exist.

Therefore, it is not possible to respond flexibly when, for example, a device is temporarily removed from the system. This caused a problem, especially when the specified device was unable to respond due to a malfunction or other reason. Also, even if the receiving device is performing other processing, it must interrupt it and respond to the sending device.
In addition to complicating the communication control process, a problem also occurred in that the process being performed at the time was delayed. Also, in the prior art, once control of the bus is passed to the sender and receiver, it does not return to controller mode or bus-free mode until a certain break occurs. therefore,
Even when the terminal is in the state of transmitting or responding, if it does not execute it, it does not enter controller mode or bus-free mode, resulting in paralysis of the entire system. Furthermore, since the conventional technology is based on the premise of constructing a small-scale system, the number of connected devices is limited, resulting in poor versatility.

Purpose The present invention overcomes the drawbacks of the prior art and provides a host with intelligent functions. ! In a communication system consisting of several terminal devices, it is possible to collect information without any problem even if all the terminal devices are not present, and it is possible to send programs and data to all terminals at once or to each terminal. The purpose of the present invention is to provide a communication system for multiple terminal devices that can perform transmission and that can centrally control all terminals by a host.

According to the present invention, in a communication system for a plurality of terminal devices connected to a host computer to exchange data in parallel, the communication system includes a relay device for driving communication signals. The terminal device and the host computer are connected via this relay device, each terminal device is set with a unique number to distinguish it from other terminal devices, and the signal line in the communication system is used to transfer data from the host computer to the terminal device. a first data line that sends
It has a second data line that sends data from the terminal device to the host computer, a terminal selection signal line that specifies the unique number of the terminal device, and a data transfer line that indicates whether the terminal device is transferring data to the host computer. When a computer sends data to a terminal device, it sends the data on the first data line while sending the unique number of the desired terminal device through the terminal selection signal line, and when the terminal device sends data to the host computer, the host computer When the unique number of the own terminal device is designated, the data transfer line indicates the presence of data transfer to the host computer, and the data is sent via the second data line.

According to the present invention, the relay device in the communication system described above includes a circuit that energizes to a predetermined level a signal line that sends a signal from the terminal device to the host computer, including the data transfer line and the second data line. have

According to the present invention, the terminal device in the communication system described above further includes terminal number identification means for identifying that the unique number of the terminal device has been sent from the host computer via the terminal selection signal line; Data transfer notifying means in which one input terminal is connected to the output of the terminal number identification means, the other manual terminal is connected to the output of a flag indicating that data is being transferred to the host computer, and the output terminal is connected to a data transfer line indicating that data is being transferred. When the data transfer notification means manually outputs identification indicating that the unique number of the own terminal device has been sent from the terminal number identification means when the flag indicating data transfer is set, the data transfer notification means performs data transfer. Sends a signal indicating presence to the host computer.

DESCRIPTION OF THE EMBODIMENTS Next, reference will be made to the accompanying drawings to explain the present invention. ! An embodiment of a communication system in several terminal devices will be described in detail.

Referring to FIG. 2, as an embodiment of the communication system for multiple terminal devices according to the present invention, 15 relay devices 3 are connected to a host computer 1, and each relay device 3 accommodates 8 terminal devices. The system configuration diagram at the time is shown.

The host computer l connects to the terminal device 5 via the relay device 3.
This is a control device that controls communication when transmitting and receiving parallel data. That is, if the corresponding terminal 5 does not perform the transmission or response for a predetermined period of time even if the host 1 enters the transmission or response state, the host 1 determines that the time has run out and moves on to the next process. Therefore, even if the terminal device 5 is removed from the system in the middle of a series of processes or cannot respond while the process is being executed, communication with other terminal devices 5 can be performed without paralyzing the communication of the entire system. The input/output circuit of the host computer l is connected to the connection cable 100.
It is connected to the relay device 3 by.

The middle device 3 is a device that drives the signals since the input/output circuit of the host computer 1 cannot drive all the terminal devices 5. The relay device 3 also connects the terminal device 5
In addition to the signal drive function of extending the connection distance between the terminal 5 and the host 1, it also serves to avoid collisions of signals from the terminal 5.

By this relay device 3, eight terminal devices 5 are connected to one
It can be treated as one unit. The relay device 3 is connected to the input/output circuit of the terminal device 5 via a connection cable 300.

The terminal device 5 is a device with an intelligent function that performs predetermined processing, and completes one processing by transmitting processing results to the host computer 1. Each terminal device 5 has a unique identification number different from that of other terminals, and performs data communication with the host 1 by selecting this number from the host 1.

One of the features of the communication system in this embodiment is that the terminal numbers of the connectors connecting the host 1 and the relay device 3 and the relay device 3 and the terminal device 5 are all the same. In particular, the data lines include one-way signal lines that send signals to the host 1 measuring terminal 5 side (group) and one-way signal lines that send signals to the terminal 5 side and the host l side. In this method, a large number of terminals 5
This is because the relay device 3 is interposed to connect the signals, so it is necessary to clarify the direction of the signal.

FIG. 3 shows the types of communication signals in this embodiment that correspond to the terminal numbers of the connectors. Terminal number 1
The mode select signals MOD to 3 are sent from the host 1 to the terminal device 5 and are signals that indicate the state of this device 5. The mode select signal NOD consists of 3 bits,
Eight states are sent to the terminal 5 side by mode select signals ll40DO-3. Note that the mode select signal MO
The type and content of D are arbitrarily set according to the processing content of the connected terminal device 5.

Terminal select signal MSEI for terminal numbers 5 to 1l, 0* to
Six signals designate the identification number of the terminal device 5.

This signal output from the host 1 to the terminal device 5 allows the user to select a desired terminal 5 from among a maximum of 120 terminal devices 5.
Host I selects . The upper 4 bits fMsEL6 to MSEI-301 of this signal MSEL specify one relay device 3 from among the connected relay devices 3, and the remaining 3 lower bits fMsEL21 to MSEI-301 specify the relay device 3 among the connected relay devices 3. ．．
0 terminal device 5 connected to this relay device 3 with
is specified. Note that the top 4 of this signal MSEL
If the bit is hexadecimal rFJ (11111), it means host 1 is specified.

Data IliilHDO to 7 of terminal numbers 12 to 19 and data strobe HSTRB of terminal number 2I are used to send data from the host 1 to all terminal devices 5 or to a specific terminal device 5 according to the mode indicated by the mode select signal MOD. This is the data line that sends the data. Also, terminal numbers 24 to 3
The data lines MD O to 7 and the data strobe line MSTRB with terminal number 33 are connected from the terminal device 5 to the host l.
This is a signal line that sends data to.

Data transfer flag MTR for terminal number 4, terminal device 5
This is a signal that requests data transfer from the host l to the host l. Note that this transfer flag MTR is output from the terminal device 5 to the host 1 in a predetermined mode. During this signal MTR, the terminal device 5 sets a data transfer request flag, and when the pilgrimage number of the terminal device 5 is sent from the host 1, it is sent to the host 1. The interrupt line MINT with terminal number 23 is a signal output when the terminal 5 interrupts the host l.

Note that the various signals shown in the figure are based on the assumption that the communication system in this embodiment is applied to an IC card inspection system described later, and the present invention is of course not limited to this. . That is, the mode select signal MOD. The terminal select signal MSEL, the number of bits of the data line, etc. can be arbitrarily set depending on the system configuration and its processing contents.

FIG. 1 shows a host computer 1 in this embodiment,
The configurations of a relay device 3 and a terminal device 5 are shown. In this figure, the host computer 1 and the terminal device 5 are input/output circuits that are directly related to this embodiment. The host input/output circuit 10 of the host computer 1 is composed of a plurality of driver groups and resistors, and is connected to various signal lines of the parallel output circuit 12 of the host 1.

That is, the driver group l4 includes 12 drivers 14-
The input side of each driver l4 receives the mode select signal MO of the parallel output circuit l2.
DO~2. It is connected to the data lines HDO-7 from the host 1 and its data strobe HSTRB*. Driver group ■6 includes seven drivers 16-1 to l6.
-7, and the terminal select signal of the parallel input/output circuit 12 is connected to its input side.

Driver group l8 includes eight drivers 18-1-18-8.
The output side is a parallel input/output circuit l2.
connected to the data line from the terminal. Driver group l
8 is also connected to the terminating resistor 22 at its input side. The driver group 20 includes three drivers 20-l to 20-.
3, the output side of which is a parallel output circuit I.
It is connected to the data transfer flag, interrupt line, and data strobe from the second terminal. The driver group 20 also includes:
The human power side is connected to a pull-up resistor 24.

The relay devices 3-1 to 3-15 each include a plurality of driver groups, a matching circuit 36, and a stage number setting section 38.

In each driver group of each relay device 3, driver groups having the same reference numerals are respectively connected to corresponding driver groups of the host input/output circuit 10 via signal lines 10RO. The driver group 3o is a driver that relays mode signals, transmission data, and data strobes from the host l to the terminal device 5, and includes 12 drivers 30-1 to 30-12.
It is made up of. The input side of the driver group 30 is a signal! Drivers 14-1 to 14- through 11110, respectively.
It is connected to the output side of 12.

The driver group 32 and the driver group 34 are drivers that drive a terminal select signal from the host 1 to the terminal device 5. These driver groups are connected in series, and each has seven drivers 32-1 to 32 and 34-1 to 34-.
It consists of 7. The input side of each driver group 32 is connected to the drivers 16-1-16-7 via a signal line 120.
The output sides of the drivers 32-1 to 32 are connected to the input sides of the drivers 34-1 to 34. The output sides of the drivers 32-7 to 32-4 are also connected to a matching circuit 36.

Also connected to the matching circuit 36 is a stage number setting section 38 in which a stage number is set using 4 bits. The matching circuit 36 outputs the output values of the drivers 32-7 to 32-4 and the stage number setting section 38.
If the set values match, the circuit sends an output 360 to the driver 40 and makes it conductive. Note that "0" is set in the stage number setting section 38 of each relay device.
Different unique identification numbers are given from ``E'' to ``E''. Specifically, the relay device 3-1 has the number "0", the relay device 3-2 has the number "l", and so on. , the number rEJ is set for the relay device 3-15.

The driver group 40 is a driver that relays data from the terminal device 5 to the host computer 1.
-1 to 40-8. These are normally in a high impedance state and become conductive when inputting the output 360 from match circuit 36. Driver 40-
The output sides of 1 to 40-8 are connected to the human power side of the driver 18-1-18-8 via a signal line 130, and a terminating resistor 44 is connected to each human power side.

The driver group 42 is a driver that drives a signal indicating the presence of data transfer from the terminal device 5, an interrupt signal, and transmission data to the host 1. The driver group 42 includes a single collector gate fO. (1:l), and performs wired OR operation. In other words, driver 42-1
42-3 are connected to the pull-up resistors 24-1 to 24-3 via the signal line 140 at their respective output sides, thereby forming a bus drive. driver 42
-1 to 42-3 are also connected at their respective input sides to pull-up resistors 46-1 to 46-3. These pull-up resistors 46-1 to 46-3 cause collector gate drivers 60 to 64 of the terminal device 5, which will be described later, to similarly perform a wired OR operation.

The terminal device 5 has a terminal device input/output circuit 70, which connects various signal lines of the parallel input/output circuit 72 of the device 5, namely, a mode signal line, a terminal number matching signal line, a data line from the host, and a terminal device input/output circuit 70. It is connected to the data strobe line from the terminal, the data transfer flag line from the terminal, the interrupt line from the terminal, the data strobe line from the terminal, and the data line from the terminal. The terminal device input/output circuit 70 includes a plurality of driver details 50, 56 i5 and 66, drivers 58 to 64,
It is composed of a matching circuit 52, a terminal number setting section 54, and an AND circuit 68.

The driver group 50 is a driver that receives a mode signal from the host 1. The driver group 50 includes drivers 50-
1 to 50-3, and their input side receives the signal f
The i310 is connected to the output sides of the drivers 30-l to 30-3, and these output sides are connected to the mode signal line of the parallel input/output circuit 72.

The matching circuit 52 receives the terminal select signal from the host 1, and when this signal indicates the own terminal device 5, the matching circuit 52 outputs “H”.
” level terminal number match signal to the parallel input/output circuit 72.
This is the circuit that sends it to. The matching circuit 52 is connected to the driver 34-l.
It is connected to the output side of .

The terminal number setting section 54 is an identification number setting section in which the unique number of the terminal device 5 is set in 7 bits. That is,
For example, "00" is set in hexadecimal in the terminal number setting section 54 of the terminal device 5-1-1, "01" is set in the terminal number setting section 54 of the terminal device 5-12, and "01" is set in the terminal number setting section 54 of the terminal device 5-12. "E7" is set in the terminal number setting section 54 of the last connected terminal device 5-15-8.

The driver group 56 is a driver that drives transmission data from the host 1. The driver group 56 includes the driver 5
6-I to 56-8, their input sides are connected to the drivers 30-4 to 30-11 via the signal line 310, and their output sides are connected to the data line from the host of the parallel input/output circuit 72. has been done. The driver 58 is a driver that drives a data strobe for transmission data from the host I. The driver 58 has its human input side connected to the driver 30-12 via a signal line 310, and its output side connected to a data strobe from the host. When the mode set by the mode select signal sent from the host l is the reception mode and the terminal select signal matches the identification number of its own terminal, the terminal device 5 receives the data transmitted from the host l and its data. Receive data strobe.

The driver 60 and the AND gate 68 are circuits that notify the host l of data transfer from the terminal 5.

The AND gate 68 has one input terminal connected to the output side of the matching circuit 52 and the other input terminal connected to the parallel output circuit 72.
are connected to the data transfer flag of rH.
” level, an output signal of “H” level, that is, the presence of data transfer from the terminal, is sent to the input side of the driver 60. The output side of the driver 60 is connected to the input side of the driver 42-1 via a signal line 340.

The driver 62 is a driver that sends an interrupt signal from the terminal 5 to the host l. That is, the driver 62 has its human power II+ connected to the interrupt line of the parallel input/output circuit 72, and its output {l11 is connected to the human power side of the driver 42-2 via the signal line {40.

The driver 64 is a driver that drives a data strobe for transmission data from the terminal 5. The output side of the driver 64 is connected to the input side of the driver 42-3 via a signal line 340.

The driver group 66 is drivers that drive transmission data from the terminal 5. The driver details 66 are the driver 66
-1 to 66-8, each input side is connected to the data line of the parallel human output circuit 72, and each output side is connected to the human power side of the drivers 40-1 to 40-8. These are normally high impedance states,
The parallel input/output circuit 72 becomes conductive due to the data line enable signal.

As shown in the figure, a transmission line for signals sent from the terminal device 5 to the host l is connected to a terminating resistor 44 or a pull-up resistor 46 of the relay device 3. Therefore, even if the terminal device 5 is removed due to a failure or adjustment, the relay device 3 will not be affected by the power because it is energized to a predetermined level, and the communication cable 300 can be simply removed from the terminal device 5. It can be handled by

FIG. 4 shows a connection diagram of the open collector output driver in this system.

Note that, in order to facilitate understanding, the figure shows a connection diagram when eight terminal devices 5 are connected to one relay device 3. As described above, in this embodiment, by wired OR-connecting the oven collector driver gate, a bus drive that can avoid collision of signals from the terminal 5 with a simple control method is realized.

The operation of this embodiment will be explained using FIGS. 1 and 2. When the host 1 sends data to the terminal device 5, it uses a mode select signal to change the mode to a reception mode on the terminal side and sends the data. In order to identify the terminal device 5, its terminal number is sent by a terminal select signal. For example, when the host 1 sends data to the terminal device 5-2-2, the host 1 sends the data to all the relay devices 3 while sending a select signal of r0001 001J, that is, r IIJ in hexadecimal. As a result, the transmission data and the terminal select signal from the host 1 are received by all the terminal devices 5 via the relay device 3.

Each terminal device 5 determines whether or not its own terminal has been selected by the host 1 based on the terminal select signal. In this case, r is entered in the terminal number setting section 54 of the terminal device 5-2-2 in hexadecimal.
Since IIJ is set, a coincidence signal is output from the coincidence circuit 52 of this terminal device 5, and this terminal device 5-2
-2 receives data from host l.

Further, the host 1 sequentially changes the terminal select signal at a predetermined timing to check whether each terminal has set a data transfer flag. FIG. 5 shows the selection order of the terminal devices 5. In this embodiment, the terminal device 5 is actually selected by a 7-bit select signal, but conceptually, the upper 4 bits of the select signal fMsEL 6 - MS
Select relay device 3 with EL 311 and set the lower 3 bits (M
Select the terminal device 5 accommodated in the selected relay device 5.

That is, the alteration of the upper 4 bits is performed after the chain of the lower 3 bits has gone around once. Note that rFJ indicated by the chain of the upper 4 bits indicates the host computer 1, as described above.

Further, the mode select signal is changed in a predetermined order as shown in the figure. This is to prevent two or more signal lines from changing at the same time, and is intended to prevent the occurrence of erroneous signal states (especially during transition periods). host l is
When a signal line is changed, the signal state is maintained for a predetermined period of time until the signal becomes stable.

When the terminal device 5 has data to be sent to the host l, the terminal device 5 sets the data transfer flag from the terminal 5 to the r[-1'' level and waits for its own terminal to be designated by the host. When the host 1 uses a mode select signal to set the mode to a mode for data transmission from a terminal, and transmits a select signal specifying the terminal device 5-1-1, for example, the matching circuit 36 of the relay device 3-1 outputs a matching signal. 360 to the driver 40 to make its gate conductive. When the terminal device 5-1-1 receives the select signal addressed to its own terminal, the matching circuit 52
The coincidence signals from the parallel output section 72 and the input terminals of the AND gate 68 are respectively sent.

When the terminal device 5-■-1 sets the data transfer flag, the output of the AND gate 68 becomes "H" and the output of the driver 60 becomes "L". As a result, the driver 42-
1 becomes "L", and the host 1 is notified that there is data transfer from the terminal 5. When the host 1 receives the request for data transfer from the terminal 5, it fixes the terminal select signal to the terminal device 5-1-1 and prepares to receive future data.

Further, when the terminal device 5-l-1 that has set the data transfer flag receives the terminal number matching signal, it makes the driver group 66 conductive by the data line enable signal of the parallel input/output circuit 72, and transmits the data to the host 1. do. As mentioned above, since the driver 40 of the relay device 3-1 is in a conductive state, the data of the terminal device 5-11 is transferred to this driver 40.
is sent to host l via. Host l is terminal device 5-
When the data from 1-1 is received in synchronization with the data strobe signal from the terminal, data reception completion is returned to this terminal device 5-1-1. Upon receiving the completion of data reception, the terminal device 5-11 lowers the data transfer flag from the rHJ level to the "L" level.

Next, an I
An embodiment in which the present invention is applied to a C card inspection system will be described. FIG. 6 shows a system configuration diagram of the same embodiment, and FIG. 7 shows the contents of the mode select signal. In this embodiment, the host computer 1 confirms the connection state of the IC card inspection device 5 (terminal), receives the IC card inspection results from this device 5, and totals and outputs the results.

In the same embodiment, there are eight types of modes, modes O to 7. Modes O~2, 4 and 5 are in the state where the [C card is being inspected]. Further, mode 3 is an intermediate state in which terminal registration, inspection interruption, and inspection are completed and transition to a stopped state. Additionally, modes 68 and 7 are inactive.

Mode 0 is an intermediate mode transition state. Mode ■ is 1
This is a state in which data is transferred from one IC card inspection device 5 to the host computer 1. Mode 2 is a state in which data is transferred from the host computer 1 to one inspection device 5. During this one-to-one transmission, a delimiter code such as a carriage return is attached to the end of the data. Host 1 does not change the mode until this delimiter code is received. The registered state of mode 3 is the state when mode 3 is entered from the stopped state (mode 7). When each terminal 5 recognizes this state, it sets a data transfer flag if there is no abnormality. As a result, the host computer 1 sequentially changes the terminal number of the terminal select signal and registers the flagged terminal 5. In addition, the inspection completion status of mode 3 is as follows:
This is the state in which it has been determined that all processes have been completely completed.

This occurs in an intermediate state before transitioning to the stopped state (mode 7). Furthermore, the test interruption state of mode 3 is a state in which the test has not been completed but there has been a command to interrupt the test, or a state has become such that the test has no choice but to be interrupted. The terminal device 5 that recognizes this state performs an interruption process and then sets a data transfer flag. In this case, the host computer l performs processing operations similar to those for terminal registration. Mode 3 starts when all registered terminals 5 set their data transfer flags.
Exit and move to mode 7.

Mode 4 is a state in which the host l checks whether there is a terminal 5 that has generated an interrupt, and here the presence or absence of an interrupt is simply checked. Mode 5 is. In mode 4, when the host l recognizes that there is an interrupt, it checks which terminal 5 is requesting the interrupt.

Mode 6 is for all terminals 5 from host computer 1.
This is the state where data is transferred all at once. Since programs are transferred, all codes may exist in the data. In this case, the module select signal is set to host 1 (rFJ), a division code for the data to be transmitted is provided, and then the data continues. The end of data transmission Y is notified by changing mode 6 to mode 7. Mode 7 is a stop state or a test state.

The host 1 changes the mode signal according to the order shown in FIG. 8 and tests the rC card. Each mode changes in a predetermined order as shown in the figure. Similar to the mode select signal described above, this is to prevent two or more signal lines from changing at the same time, and is intended to prevent the occurrence of erroneous signal states.

The mode signal also remains in that signal state until the signal stabilizes.

When the power is turned on and inspection begins, host computer 1
attempts to obtain the necessary information by changing the mode signal and mode select signal. Therefore, in this embodiment, there are two modes: a state search mode and an interrupt processing mode. The information obtained in the two modes is substantially different from the internal processing of the host computer I. These two modes are 1
Each time the service is performed, it switches to the other one.

In mode 0, which does not operate as an intermediate mode of processing, the terminal 5 is not affected at all. Therefore, at this time, the host computer 1 can independently perform its own processing separate from the IC card inspection. This also applies to mode 7.

On the terminal 5 side, when the inspection becomes possible, the fC card to be inspected is inserted into the inspection device 5, thereby entering the inspection state. Once the test device 5 enters the test state, it concentrates on its processing and does not accept the mode signal or mode select signal from the host 1 until it reaches an intermediate break or the end. The inspection device 5 sets a data transfer flag when the inspection of the attached IC card is completed. and,
Upon receiving the selection signal indicating the own terminal 5, the test result is reported to the host computer 1. When the host computer 1 receives the test results from all the connected terminals 5, it totals them and ends the test process.

In this embodiment, since the terminal select signal is 7 bits, the maximum number of terminals that can be accommodated is 120, but the present invention is not particularly limited to this. In this embodiment, in order to facilitate understanding, it is assumed that the terminal device 5 is accommodated through l relay devices 3, but the number of relay devices 3 interposed between the host computer 1 and the terminal device 5 is as follows. It is not limited to. That is, in the present invention, the terminal device 5 may be connected via the relay device 3 in a connection form as shown in FIG.

Effects As described above, according to the present invention, even if a terminal device has to be removed from the system due to a malfunction or adjustment, it can be handled simply by removing the cable connected to the input/output circuit of the terminal device, and there is no impact on other devices. Never give up. Furthermore, once the terminal device starts processing, it can concentrate on the predetermined processing, and there is no need to respond to signals from the host computer 1 every time.If the terminal device wants to report the processing results, it can notify the host by indicating that data is being transferred. can. Thereby, the processing of the terminal device and the communication processing between the systems are clearly distinguished, and programming of the terminal device is facilitated. Furthermore, the circuits necessary to configure this communication system, that is, the host 1, the human output circuits 10 and 70 of the terminal device 5, and the relay device 3, can be configured with simple circuits as described above, which is economical. In addition, host duo J. Test results of many terminal devices 5 can be collected one after another in one night. Further, since there is no particular restriction on the number of relay devices interposed between the host computer and the terminal device, it is possible to cope with the case where the host and the terminal device are far apart.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the human output circuit of a host computer and a terminal device, and the internal configuration of a relay device. FIG. 2 is a system configuration diagram showing an embodiment of a communication system for multiple terminal devices according to the present invention. 3 is a signal configuration diagram showing the configuration of various signals corresponding to the terminal numbers of the connection cable in the embodiment shown in FIG. 1, and FIG.
FIG. 5 is a circuit diagram showing the connection circuit of the driver. FIG. 5 is an operation explanatory diagram showing the selection operation of the terminal select chain. FIG. 6 is a system configuration diagram when the present invention is applied to an IC card inspection system. The figure is an explanatory diagram showing the types of mode signals in the IC card inspection system of Figure 6, and Figure 8 is an explanatory diagram showing types of mode signals in the IC card inspection system of Figure 6.
Operation explanatory diagram showing the selection operation of each mode in the C card inspection system, No. 9- is a system configuration diagram showing the general form of the communication system in the present invention. Description of main part #''= I Host computer relay device. Terminal device Host person output circuit Parallel input/output circuit ~ 34. 40. 42. 50. 56 ~ 66 Driver 1 3. 5. 10. 12. 72. 14 ~20.30 22.44 24.46 . 36.52 38. 54. Termination resistor pull-up resistor matching circuit Stage number setting section Terminal number setting section

Claims (1)

[Claims] 1. A communication system for multiple terminal devices that connects a plurality of terminal devices to a host computer and sends and receives data in parallel, the communication system having a relay device that drives communication signals, The terminal device and the host computer are connected via the relay device, each terminal device is set with a unique number to distinguish it from other terminal devices, and a signal line in the communication system is connected from the host computer to the host computer. a first data line that sends data to a terminal device; a second data line that sends data from the terminal device to the host computer; a terminal selection signal line that specifies a unique number of the terminal device; a data transfer line indicating that data is to be transferred to the host computer, and when the host computer sends data to the terminal device, it sends the first data while sending the unique number of the desired terminal device through the terminal selection signal line. When the terminal device sends data to the host computer, when the host computer specifies the unique number of its own terminal device, the data is transferred to the host computer via the data transfer line. 1. A communication system for a plurality of terminal devices, characterized in that the data is sent via a second data line. 2. The communication system according to claim 1, wherein the relay device energizes signal lines that send signals from the terminal device to the host computer, including the data transfer line and the second data line, to a predetermined level. A relay device characterized by having a circuit. 3. The communication system according to claim 1, wherein the terminal device includes: terminal number identification means for identifying that the unique number of the own terminal device has been sent from the host computer via the terminal selection signal line; A data transfer device whose input terminal is connected to the output of the terminal number identification means, whose other input terminal is connected to the output of a flag indicating that data is being transferred to the host computer, and whose output terminal is connected to the data transfer line that indicates that data is being transferred. and notification means, the data transfer notification means outputting an identification to the effect that the unique number of the own terminal device has been sent from the terminal number identification means when the flag indicating data transfer is set. A terminal device, when input, sends a signal indicating data transfer to the host computer.