JPH077373B2 - Interface system - Google Patents

Description

The present invention relates to an interface system for connecting a plurality of interface devices to a common bus.

[Conventional technology]

FIG. 3 shows the configuration of a system for connecting a plurality of interface devices (units) that have been widely used in the past.

In FIG. 3, reference numeral 1 denotes a processor unit, which selectively selects the basic unit I / O unit 3 and interface (I / O) units 5-1 and 5-2, and which is connected via the selected interface unit. Information communication with external devices.

Rack select lines 4-1 to 4-n are provided between the basic unit interface unit, the first to nth interface units 5-1 to 5-n, and the processor unit 1 to select an interface. There is. The input / output processor 2 provided in the processor unit can operate the selected interface unit by supplying a signal designating the interface unit to the rack select lines 4-1 to 4-n by the address generator 2-1. It becomes a state. The information transferred from the selected interface unit is sent to the input / output processor 2 via a bus (not shown).

Here, the first to nth interface units are additional interface units.

For example, when seven interface units are added, eight rack select lines are required, and the number of rack select lines must be increased as the number of additional interface units increases.
In order to solve this drawback, the next proposed connection method of the interface unit (second conventional example) is shown in FIG.

In FIG. 4, the same parts as those in the first conventional example shown in FIG. 3 are designated by the same reference numerals.

The second conventional example is an example in which the rack select lines 4 are connected by a common bus. An identification number is assigned to the interface unit in advance, and for example, as shown in the figure, the three rack select lines are provided with identification numbers of 3 bits. The input / output processor 2 selects the extension interface unit indicated by the identification number by supplying the indicated rack select signal.

On the other hand, on the extension interface unit 5 side, as shown in FIG. 5, a setting switch 5A for setting the identification number and a comparator for identifying the rack select signal are provided.
5B is provided. The comparator 5B compares the identification number set by the setting switch 5A and the identification number indicated by the rack select line, and when the identification numbers match, the comparator 5B determines that this interface unit has been selected, The coincidence signal is output to the control circuit 5C of the interface unit as a select signal indicating the operable state.

In the second conventional example as described above, there is an advantage that the number of main lines of the rack select line 4 does not have to be increased even if the number of additional interface units is increased. However, if the setting switch 5A is not provided in each additional interface unit. However, there has been a drawback that the operator has to operate the setting switch 5A to set the identification number of the interface unit.

In order to solve this drawback, the structure of the improved interface unit is shown in FIG.

In FIG. 6, a subtracter 5AA for subtracting the input signal by "1" and outputting the subtracted signal is provided between the extension interface unit 5 and the extension interface unit (not shown) at the next stage. Further, in the extension interface unit 5, a "0" detector 5BB for detecting that the signal of the rack select line 4 is "0", that is, all the levels are "L", is provided.

When the input / output processor 2 supplies the identification number to be selected to the rack select line as a 3-bit signal, this signal is sequentially reduced by the subtractor 5AA of each unit and becomes "0" in the target unit. Therefore, the interface unit that detects this "0" signal is the interface unit that the input / output processor selects.

This connection method has made it possible to eliminate the drawback of the operator setting the identification number.

[Problems to be Solved by the Invention]

In the interface system of the second conventional example as described above, the number of interface units that can be added is determined by the number of rack signal lines, but the number of rack signal lines is increased to allow the addition of a large number of interface units. In other words, there is a problem to be solved that it is difficult to confirm when more than the specified number of extension units are connected. This point will be briefly described.

For example, if the number of rack signal lines is 10, the number of interface units that can be added is very large, 2 ¹⁰ . Therefore, when the interface unit shown in FIG. 6 is used, it is necessary for the operator to visually count the existing interface units in order to increase the number of interface units.

Therefore, an object of the present invention is to solve the above-mentioned problems and provide an interface system capable of automatically detecting that a prescribed number or more of interface devices are connected.

[Means for Solving the Problems]

In order to achieve such an object, the present invention sends an address for selectively selecting and designating a plurality of interface devices from an address generator of a main device to a serially connected interface device via a signal line. In the interface system, each of the interface devices subtracts the input address and outputs the subtracted address to the interface device of the next stage, and the input address before subtraction by the subtractor is a predetermined address. An address detector that sends the detection signal to the main body device upon detection is provided, and the main body device outputs the specific address from any of the plurality of interface devices when the specific address is output from the address generator. When a detection signal is received, a predetermined number or more of the interface devices are connected. It is a fact that comprises a discriminator for discriminating characterized by that.

[Work]

In the present invention, an empty address that does not specify the interface device is provided as a specific address, and when the empty address is sent from the main device, the empty address is sequentially subtracted by the subtractor of the interface device. When one of the detectors of the interface device sends a detection signal in response to the discriminator of the main device, the discriminator is discriminated because the interface devices are connected in excess of the predetermined number of connectable devices. Can automatically detect the excess connection of the interface by receiving the detection signal.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the basic configuration of the embodiment of the present invention.

In the present embodiment, a signal line 13 for transmitting a signal notifying that a rackover notification has been added is connected to one end of a discriminator 2-2 of the input / output processor 2 in the system configuration of the second conventional example shown in FIG. A signal indicating that the rack select signal is "0" is output from the extension units 20-1 to 20-7 to the rack over notification line 13 in the signal form of the level "H".

Also, as the identification number for selecting each extension unit, the basic I / O is "0", the first extension interface unit 20-1 is "1" ... the seventh extension interface unit.
20-7 is assigned to "7" and the interface unit is selected by a 3-bit rack select signal.

The basic interface unit is not connected to the rackover notification line.

Therefore, "0" is an empty address when confirming the interface connection.

Further, the input / output processor is provided with a discriminator 2-2 that discriminates that a predetermined number or more of extension interface units are connected when detecting that a signal of level “H” is generated in the rackover communication line. . A known signal level determiner using a comparator or the like may be used as this determiner.

FIG. 2 shows the circuit configuration of the extension interface unit according to the embodiment of the present invention.

In FIG. 2, a subtractor 5AA and a “0” detection circuit 5BB similar to the conventional example shown in FIG. 6 are provided in the extension interface unit 20, and in the “0” detection circuit 5BB,
When it is detected that the rack select signal is "0",
The "0" detection signal indicating that is output to the control circuit 5C and also output to the rack over notification line 13.

Returning to FIG. 1, the operation of this embodiment will be described.

When the rack select signal "0" is output from the input / output processor 2 at the time of power-on initial, that is, when the basic unit interface unit 3 is specified, the subtracter 5AA of each extension interface unit starts from the subtractor of the basic unit interface unit. Thus, the value of the rack select signal is sequentially subtracted from 0 → 7 → 6 ... → 1.
If the number of connected extension interface units 20 is within the specified range,
Since -1 to 20-7 do not detect the rack select signal "0", the "0" detection signal is not generated on the rack over notification line 13.

Next, for example, when the eighth expansion unit 20-8 is connected in excess of the specified number, when the input / output processor 2 similarly outputs a rack select signal of "0", the rack select signal is added to the expansion unit. When it is input to 20-8, it becomes "0", so the rack select signal "0" is detected by the O detection circuit 5BB of the extension interface unit 20-8, and the "0" detection signal is output to the rack over notification line 13. To be done. The input / output processor 2 can determine that the number of extension interface units is over by inputting this "0" detection signal.

On the other hand, when the input / output processor 2 outputs, for example, "1" as the rack select signal during normal system operation with the regular number of additional interface units connected, the first additional interface unit 20-
The “0” detection signal of 1 is output to the rack over notification line 13.
Therefore, in the present invention, the input / output processor 2 can know that the selection of the extension interface unit is surely performed by receiving the "0" detection signal. In other words, the "0" detection signal is generated. By not doing so, there is an advantage that it is possible to know the failure of the extension interface unit.

Next, the following can be considered for the application form of the present embodiment.

1) In the present embodiment, the basic unit interface unit 3 and the rackover notification line are not connected, but when it is desired to confirm the selection of the basic unit interface unit, the basic unit interface unit 3 is connected to the rackover notification line.
However, the identification numbers for the interface units are sequentially "1", "2" from the basic unit interface unit 3.
It is recommended that the identification number “0” be set as an empty address in order to detect rack-over.

〔The invention's effect〕

As described above, according to the present invention, an empty address that does not specify the interface device is provided as the specific address, and when the empty address is sent from the main device,
This empty address is sequentially subtracted by the subtractor of the interface device. When one of the detectors of the interface device sends a detection signal in response to the discriminator of the main device, the discriminator is discriminated because the interface devices are connected in excess of the predetermined number of connectable devices. By receiving the above-mentioned detection signal, it is possible to automatically detect the excess connection of the interface.

Further, the present invention has an effect that it is not necessary to significantly change the conventional subtraction type interface device system in order to realize the new function of confirming the excess connection of the interface device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an embodiment of the present invention, FIG. 2 is a circuit diagram showing a configuration of an interface unit of the embodiment of the present invention, and FIG. 3 is a block diagram showing a system configuration of a first conventional example. FIG. 4 is a block diagram showing the system configuration of the second conventional example, FIG. 5 is a circuit diagram showing the configuration of the extension interface unit shown in FIG. 4, and FIG. 6 is a diagram showing the extension interface unit shown in FIG. It is a circuit diagram which shows another structure. 1 ... Processor unit, 2 ... I / O processor, 3 ... Basic I / O unit, 4 ... Rack select line, 5,20 ... Expansion interface (I / O) unit, 5A ... Setting switch, 5B: Comparator, 5C: Control circuit, 5AA: Subtractor, 5BB: O detection circuit, 13: Rackover notification line.

Claims (1)

[Claims] 1. An interface system for transmitting an address for selectively selecting and designing a plurality of interface devices from an address generator of a main body device to the interface device connected in series via a signal line, the interface system comprising: Each of the devices subtracts the input address and outputs it to the interface device of the next stage, and when the subtractor detects that the input address before the subtraction is a predetermined address, the detection signal is sent to the main device. When the main body device receives the detection signal from any one of the plurality of interface devices when the specific address is output from the address generator, the main body device determines in advance. A discriminator for discriminating that more than the specified number of the interface devices are connected. Interface system, characterized in that was e.