JPH0331299B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to extending the length of an interface bus such as GP-IB that interconnects multiple devices such as computers, voltmeters, and printers. The present invention relates to the node used, and particularly to control of operating mode switching between a specific mode and a general mode in this node.

<Prior Art> A system using an interface bus as shown in FIG. 3 is common for exchanging information between a plurality of devices such as computers, voltmeters, and printers.

In this figure, G ₁ to _{G 5} are the calculator, voltmeter,
Devices such as printers, b ₁ to _{b 4} are interface buses connected to devices G ₁ to G ₅ , g is devices G ₁ to _{G 5}
This is a connector that connects the interface buses _b1 to _b4 . In such a system, equipment G ₁
~ A system controller in which one device (for example, device G ₁ ) among G ₅ is responsible for the functions of a system controller that initializes the interface bus, etc., and a controller that specifies the functions of each device (talker, listener, etc.). Also works as a controller, interface bus B ₁ ~ _{B 4} and equipment
It controls information exchange between G ₂ and G ₅ .

However, GP-IB that connects multiple devices
For interface buses such as, the length and number of cables are limited depending on the number of devices.
In order to extend the length of this interface bus, an interface bus extend system using nodes and cables as shown in FIG. 4 is known.

In this figure, N ₁ to N ₄ are nodes connected to interface buses b ₁ to b ₄ of each device, and C is a node connected to nodes N ₁ to _{N 4} and connected to interface bus b ₁
This is a cable that is a serial transmission line for information exchange between the devices _G1 to _G4 on ~ _b4 , and the part E surrounded by the dotted line is an extend system that extends the interface bus.

Although this figure shows a system in which one device is connected to each node _N1 to _N4 , it is also possible to connect a plurality of devices to one node.

In such a system, like the system shown in FIG. 3, one of the devices G ₁ to _{G 4} serves as a system controller and controls the extend system and information exchange between the devices.

In the system shown in FIG. 4, for example, device _G1 serves as a system controller and a controller.

In this case, the node _N1 in the bus extend system E is set as a specific node (specific mode), and the other nodes _N2 to _N4 are set as general nodes (general mode).

First, device G ₁ outputs an interface clear signal IFC=1 onto interface bus b ₁ to initialize each interface bus in this extend system E, and node N ₁ outputs this signal IFC=1. to other nodes N ₂ to _{N 4} ,
The other devices G ₂ to _{G 4} that received this signal IFC=1 send the signal IFC=1 on their own interface buses b ₂ to b ₄ .
1 to initialize the connected information interface bus.

Next, device G ₁ sends a remote/local switching signal REN to each device G ₂ to _{G 4} to determine if the information on the data in the interface bus is an interface message for controlling the interface bus. Management information such as ATN, which indicates whether it is device data or a message, is sent to the node.
Advertise via _N1 .

Meanwhile, other devices G ₂ to _{G 4} that received this management information
outputs a signal SRQ=1 requesting service from the controller device G ₁ to each node N ₂ to _{N 4} separately, and the device G ₁ receives this signal SRQ=
1 and performs the corresponding processing.

In this way, in the extend system E of interface buses _b1 to _b4 , a signal from one system controller and controller device _G1 is sent to the specific node _N1 , cable C, and general node N2 _.
Sent to equipment G ₂ ~ G ₄ via ~N ₄ , and equipment G ₁ ~
G ₄ exchanges information.

However, in this conventional interface bus extend system, one specific device acts as both a system controller and a controller, and the transmission direction of signals such as bus management information is fixed. The troublesome work of changing the settings of each node, and configuring a system where devices connected to other nodes will automatically start backing up if the device that serves as the system controller/controller goes down. It had the disadvantage of not being able to

<Problems to be Solved by the Invention> The problems to be solved by the present invention are those in which a connected device can function as a system controller and a controller without changing the hardware settings of the device, etc. The goal is to realize a face bus node.

<Means for solving the problem> In order to solve the above-mentioned problem, the present invention receives an interface clear signal transmitted from another node, and further receives an interface clear signal output from its own connected device. The nodes of the interface bus were configured to also receive the interface clear signals associated with the interface bus and compare them to determine the mode of operation of that node.

That is, the configuration of the present invention is as follows.

At least one or more devices are coupled via an interface bus, and is used for exchanging information with devices connected to other nodes, and coupled to a cable to extend the interface bus,
In an interface bus node that forms a loop-like extend system with at least one other node, an inter-node transmission control unit receives information from an upstream node and transmits information to a downstream node; an interface bus driver that transmits an interface clear signal and bus management information received by the inter-node transmission control unit to a device via an interface bus connected to the node; and a device connected to the interface bus. When an interface clear signal is issued from the device, an interface bus receiver outputs this interface clear signal and bus management information from the device to the inter-node transmission control section, and a specific mode in which the system controller and controller are connected. When receiving the interface clear signal "1" sent from the node in the specific mode, the node enters the general mode and the interface clear signal received from the node in the specific mode switches from "1" to "0" and connects to itself. a node operation mode control unit that sets a node operation mode to a specific mode indicating that a device connected to itself is a system controller and a controller when an interface clear signal “1” is received from the interface bus for a certain period of time; This is an interface bus node characterized by:

<Effect> The arrangement of the present invention operates as follows.

When the inter-node transmission control unit receives the interface clear signal IFC = 1 transmitted from a node in a specific operation mode connected to the system controller/controller, this signal is sent to the node operation mode control unit, and this signal is sent to the node operation mode control unit. The node functions as a node in general operating mode.

Further, the node operation mode control unit determines whether the node is connected to this node after a certain period of time t has passed since the interface clear signal IFC received from another specific node switches from "1" to "0". If the interface clear signal "1" is sent from the interface bus, it is interpreted as an interface clear signal sent from the device connected to this node, and this node is changed from general mode to specific mode. It works like this.

Then, when this node is in a specific node state, it receives an interface clear signal from other devices.
If IFC=1 is received, the specific mode is switched to the general node.

<Embodiment> An embodiment of an interface bus node according to the present invention is shown in FIG.

In this figure, N is a node according to the present invention, RX is a transmitting unit for inter-node transmission that reproduces a serial signal from an upstream node via an optical fiber or coaxial cable, and outputs a signal RS, and TX is a transmitting unit for inter-node transmission. An inter-node transmission transmitter that converts the level of the signal SS from the inter-node transmission control unit 1 and transmits it to the downstream node via an optical fiber, coaxial cable, etc. 1 receives the signal RS and processes it within the node N. signal
The inter-node transmission control section 2 transmits SS to the downstream node, and the inter-node transmission control section 2 receives the upstream node information (signal RS) from the inter-node transmission control section 1 and outputs the signal to its own interface bus b. An interface bus driver 3 outputs bus management information from its own device to the inter-node transmission control unit 1 when an interface clear signal is issued from a device connected to its own interface bus b. A bus receiver 4 receives an interface clear signal IFC _bcd announced from a specific node and an interface clear signal sent from its own interface bus.
a node operation mode control unit that inputs and compares IFC _bcd/rsp , instructs other nodes to detect it, and determines the operation mode of this node N based on the reported interface clear signal IFC _sd ;
5 transmits a signal SRQ _sd requesting a service from another node to the controller device from the inter-node transmission control unit 1 when this node N enters a specific mode, and outputs it to its own interface bus b. This is the second interface bus driver that operates.

The operation of the thus configured node of the present invention and the transmission and reception of signals are as shown in the flow chart shown in FIG.

Next, a detailed explanation will be given using FIGS. 1 and 2.

When the power is turned on, the node operation mode control unit 4 sends an interface clear signal received from its own interface bus b to the inter-node transmission control unit 1.
An instruction signal BC = 0 that enables IFC _bc/rsp , remote/local signal REN _bc , and message signal ATN _bc to be broadcast to other nodes, and when this node N becomes a specific node, the standard interface bus interface of other nodes This _{node N}
functions as a general node.

When this node N is operating as a general node, the interface clear signal IFC _bcd from the specific node is sent to the interface bus b via the interface bus driver 2 and the connector g.
This interface bus b is cleared. Furthermore, the remote/local signal REN _bcd and the message signal ATN _bcd from the specific node are transmitted from the inter-node transmission control unit 1 to the interface bus driver 2, and output from the connector g to its own interface bus b. At the same time, the remote/local signal REN _bcd and the message signal ATN _bcd are transmitted from the inter-node transmission control section 1 to the downstream node by the inter-node transmission transmission section TX.

On the other hand, if the device connected to this node N outputs the service request signal SRQ=1 to the system controller/controller device,
The SRQ signal of interface bus b is output to the interface receiver 3, and further sent to the inter-node transmission control unit 1 as service request signal detection information SRQ _rsp , and sent to the system controller/controller device by the inter-node transmission transmitter TX. Sent as a response signal to a detection report instruction.

Next, when the device connected to this node N replaces the current system controller/controller and becomes the system controller/controller, this device issues an interface clear signal IFC=1. Interface bus receiver 3 receives this interface clear signal.
IFC is set to signal IFC _bc/rsp = 1, and this node N responds to the detection report instruction signal from the current specific node.
At the same time, this signal IFC _bc/rsp is sent to the node operation mode control section 4 as a response signal from the node to the inter-node transmission control section 1.

The node operation mode control unit 4 outputs the signal IFC bc/ from its own interface bus b while the interface clear signal IFC _bcd from the specific node is not output to its own interface bus b (IFC _bcd = 0 _). When _rsp = 1 is received for more than time t and a signal CHAV indicating that the line can be advertised and detected is issued from the inter-node transmission control unit 1 by the interface clear signal IFC, this node N
is set to specific mode (1), and the device connected to this node becomes the system controller and controller.

Next, a public information instruction signal BC=1 is output to the inter-node transmission control section 1. And node N is
Remote/local signal REN and message signal ATN from the device via interface bus b
is given to interface bus receiver 3, and the signal
REN _bc and signal ATN _bc are transmitted to other nodes via the inter-node transmission control unit 1.

That is, under the condition of ((IFC _{bc/rsp∩bcd )} >t)∩CHAV, this node N switches to a specific node (specific mode (1)).

Next, when the interface clear signal IFC from the self-interface bus b changes from "1" to "0", the node operation mode control unit 4 clears the signal
IFC detects _bc/rsp = 0 (condition _bc/rsp ) and outputs a signal SNS = 1 for detecting a signal from another node to the inter-node transmission control unit 1, and this node N enters the specific mode (2). , the state changes from the signal announcement state to the other node signal detection state.

Here, the other node receives the service request signal SRQ
= 1, this node N transmits this service request signal in the inter-node transmission control unit 1.
This signal SRQ _sd is transmitted to the second interface driver 5 _, and is applied from this node N to the device via the interface bus b.

Also, when the interface clear signal IFC from its own device changes from "0" to "1" (IFC _bc/rsp = 1), this node N again
Return to specific mode (1) and repeat the same operation as above.

In the detection state of specific mode (2), if another node outputs the interface clear signal IFC = 1 in order to function as a system controller and controller, and this node N detects the signal IFC = 1, the node The interface clear signal IFC = 1 of the other node from the inter-node transmission control unit 1 is the signal
It is received by the node operation mode control unit 4 as IFC _sd =1.

At the time when this signal IFC _sd is given, the node operation mode control unit 4 sets the public relations signal BC = 0, the detection signal SNS = 0, opens the signal line (line) of the interface bus, and sets this node N as a general node. Make it work.

In this way, this node N can switch and function as a specific node or a general node depending on signals from other nodes.

<Effects of the Invention> As described above, according to the present invention, in a node of an interface bus extend system, the operation mode of the node can be changed to a specific mode or a general node by a signal from another node. Since it is possible to perform switching control, there is no need to change the hardware settings every time the system configuration of the device is changed.Also, even if the system controller/control device goes down, if this is detected, By switching the operation mode of the connected nodes, the own device starts operating as a system controller and controller, and the effect is that the backup system can be automatically configured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of nodes of an interface bus according to an embodiment of the present invention, FIG. 2 is a flowchart showing switching conditions of nodes of an interface bus according to an embodiment of the present invention, and FIG. FIG. 4 is a diagram of an extend system for extending an interface bus connected to equipment. DESCRIPTION OF SYMBOLS 1...Inter-node transmission control unit, 2...Interface bus driver, 3...Interface bus receiver, 4...Node operation mode control unit, 5
...Second interface bus driver, G,
G ₁ ~ G ₅ ...Equipment, E...Extend system,
N, N ₁ to _{N 4} ... Node, b ... Interface bus, g ... Connector, RX ... Receiving section for inter-node transmission, TX ... Transmitting section for inter-node transmission.

Claims (1)

[Claims] 1. At least one device is connected via an interface bus, and is used for exchanging information with devices connected to other nodes, and is connected to a cable to extend the interface bus. , an interface bus node forming a loop-like extend system with at least one other node, an inter-node transmission control unit that receives information from an upstream node and transmits information to a downstream node, and the other node. an interface bus driver that transmits an interface clear signal and bus management information received by the node-to-node transmission control unit from the node to a device via an interface bus connected to the node; and an interface bus driver connected to the interface bus. When an interface clear signal is issued from a device, an interface bus receiver outputs this interface clear signal and bus management information from the device to the inter-node transmission control section; When the interface clear signal "1" transmitted from the node in the specific mode is received, the interface clear signal received from the node in the specific mode switches from "1" to "0" and becomes the self mode. a node operation mode control unit that sets a specific mode indicating that a device connected to itself is a system controller and a controller when an interface clear signal “1” is received from the connected interface bus for a certain period of time; An interface bus node characterized by comprising: