Communication system for transmitting divisional messages back-to-back by pre-setting blank duration between the divisonal messages prior to transmission
First Claim
1. A communication system comprising:
- a communication line;
a master device for transmitting via said communication line a request message to request that a predetermined processing be performed;
a plurality of slave devices, connected to said master device by said communication line, for, responsive to receipt of said request message via said communication line, transmitting via said communication line answer messages which are in an order corresponding to descending priorities of said slave devices;
wherein said slave devices transmit answer messages in such a manner that a communication blank duration on said communication line between an answer message from a given one of said slave devices and an answer message from a slave device having a priority immediately lower than a priority of said given one of said slave devices is a first predetermined length of time; and
at least one of said slave devices divides an answer message into a plurality of divisional answer messages if said answer message includes more than said predetermined amount of data, and sets said communication blank duration between said divisional answer messages before transmitting said divisional answer messages in such a manner that said communication blank duration between said divisional answer messages is a second predetermined length of time that is less than said first predetermined length of time, and then transmits said divisional answer messages.
1 Assignment
0 Petitions
Accused Products
Abstract
In a communication system which ensures that a slave device can successively transmit a plurality of answer messages without causing collision with another message on a communication line, in response to a request message from a diagnosis tester, control devices transmit their answer messages in the order of their priorities, with a communication blank duration provided between answer messages. If any one of the control devices has first and second answer message to be transmitted successively, the control device transmits the second answer message a communication blank duration after completing transmission of the first answer message. The control device can thereby transmit the first and second answer messages before a control device of a lower priority starts to transmit its answer message. Message collision on the communication line is thus avoided.
-
Citations
23 Claims
-
1. A communication system comprising:
-
a communication line; a master device for transmitting via said communication line a request message to request that a predetermined processing be performed; a plurality of slave devices, connected to said master device by said communication line, for, responsive to receipt of said request message via said communication line, transmitting via said communication line answer messages which are in an order corresponding to descending priorities of said slave devices; wherein said slave devices transmit answer messages in such a manner that a communication blank duration on said communication line between an answer message from a given one of said slave devices and an answer message from a slave device having a priority immediately lower than a priority of said given one of said slave devices is a first predetermined length of time; and at least one of said slave devices divides an answer message into a plurality of divisional answer messages if said answer message includes more than said predetermined amount of data, and sets said communication blank duration between said divisional answer messages before transmitting said divisional answer messages in such a manner that said communication blank duration between said divisional answer messages is a second predetermined length of time that is less than said first predetermined length of time, and then transmits said divisional answer messages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A slave device for use in a communication system wherein said slave device is connected to a master device and at least one other slave device by a communication line, said slave device comprising:
-
means for, upon receiving via said communication line a request message from said master device requesting that a predetermined process be performed, transmitting an answer message responsive to said request message to said communication line, said slave device being assigned with a priority determined in relation to said at least one other slave, so that a communication blank duration on said communication line between said answer message and an answer message from a slave device having a priority consecutive with a priority of said slave device is a predetermined length of time; and dividing means for, if said slave device has an answer message having more data than a predetermined amount to transmit, dividing said answer message into divisional answer messages and setting a communication blank duration between said divisional answer messages successively before transmitting said divisional answer messages so that said communication blank duration on said communication line between said divisional answer messages is a second predetermined length of time which is less than said first predetermined length of time and then transmitting said divisional answer messages.
-
-
10. A communication system comprising:
-
a communication line; a master device for transmitting via said communication line a request message to request that a predetermined processing be performed; a plurality of slave devices, connected to said master device by said communication line, for, responsive to receipt of said request message via said communication line, transmitting via said communication line answer messages; wherein said master device transmits a request message after confirming that a communication blank duration on said communication line has become a first predetermined length of time; and if said slave device has an answer message having more data than a predetermined amount to transmit, said slave device divides said answer message into divisional answer messages and sets a communication blank duration between said divisional answer messages successively before transmitting said divisional answer messages so that said communication blank duration on said communication line between said divisional answer messages is a second predetermined length of time which is less than said first predetermined length of time, and then transmits said divisional answer messages.
-
-
11. A slave device for use in a communication system wherein said slave device is connected to a master device by a communication line, said slave device comprising:
-
means for, upon receipt by said slave device via said communication line of a request message from said master device requesting that a predetermined process be performed, transmitting an answer message for said request message to said communication line; and dividing means for, if said slave device has an answer message having more data than a predetermined amount to transmit, dividing said answer message into divisional answer messages and setting a communication blank duration between said divisional answer messages successively before transmitting said divisional answer messages so that said communication blank duration on said communication line between said divisional answer messages is shorter than communication blank duration on said communication line after said slave device completes transmitting an answer message until said master device starts transmitting a request message and then transmitting said divisional answer messages.
-
-
12. A method of communicating in a communication system, said method comprising the step of:
-
monitoring, in a first slave device, a communication line for messages from other slave devices; measuring, in said first slave device, a first elapsed time during which there are no messages on said communication line, beginning with a termination of transmission of a message from one of said other slave devices; sending, from said first slave device, a first portion of a first message to be sent on said communication line when said first elapsed time reaches a first predetermined length of time associated with said first slave device; and if said first message to be sent is longer than a predetermined message length, setting at least one additional portion of said first message to be sent a second predetermined length of time associated with said first slave device after termination of transmission of said first portion of said first message to be sent, and then sending from said first slave device said first message to be sent on said communication line. - View Dependent Claims (13, 14, 15, 16, 17, 18)
-
-
19. A communication system comprising:
-
a communication line; a master device for transmitting via said communication line a request message to request that a predetermined processing be performed; a plurality of slave devices, connected to said master device by said communication line, for, responsive to receipt of said request message via said communication line, transmitting via said communication line answer messages which are in an order corresponding to descending priorities of said slave devices; said master device including connection confirming message transmitting means for transmitting a connection confirming message to confirm which of said slave devices is able to transmit an answer message via said communication line; each of said slave devices including first answer message transmitting means for, in response to a connection confirming message from said communication line, transmitting a first answer message that includes an identification value of said control device to said communication line, identification value storing means for sequentially storing said identification value included in said answer message transmitted by said first answer message transmitting means, and priority setting means for determining current priorities based on said identification value stored in said identification storing means; and said master device transmits a request message, and said slave devices receive said request message and transmit answer messages, based on current priorities determined by said priority setting means. - View Dependent Claims (20, 21, 22, 23)
-
Specification