Communication system between master system and multiple slave systems in time division mode where a next slave is serviced upon receipt of final acknowledgement

A data communication method between a signal processing module and successive one of a plurality of line processing modules connected to respective subscriber terminals via a communication path selector in a decentralized multi-node exchange system having a central processing module for controlling said decentralized multi-node exchange system, said signal processing module comprising a central processor for controlling operation of said signal processing module, a random-access memory for temporarily storing communication data and processing data, a read-only memory for storing application programs, a timer for performing a timer interrupt of said central processor, a serial input/output interface for enabling communication of serial data and messages between said signal processing module and a selected one of said plurality of line processing modules, and an interrupt controller for controlling said serial input/output interface, said data communication method comprising the steps:

• establishing a communication path between the signal processing module and a selected one of said plurality of line processing modules via said communication path selector;
• assigning a communication time for communication between said signal processing module and said selected one of said plurality of line processing modules;
• transmitting an initial message from said signal processing module to said selected one of said plurality of line processing modules via said serial input/output interface, and simultaneously receiving a return message from said selected one of said plurality of line processing modules via said serial input/output interface;
• when said communication time has elapsed, transmitting a final message from said signal processing module to said selected one of said selected one of said plurality of line processing modules via said serial input/output interface, after said initial message has been transmitted;
• and
• executing service for a second one of said plurality of line processing modules upon establishing a second communication path between the signal processing module and the second one of said plurality of line processing modules, when a final acknowledgment message is received from said selected one of said plurality of line processing modules via said serial input/output interface.

A data communication method between a signal processing module and successive ones of a plurality of line processing modules connected to respective subscriber terminals via a communication path selector in a decentralized multi-node exchange system having a central processing module for controlling said decentralized multi-node exchange system, said signal processing module comprising a central processor for controlling operation of said signal processing module, a random-access memory for temporarily storing communication data and processing data, a read-only memory for storing various programs, a timer for performing a timer interrupt of said central processor, a serial input/output interface for enabling communication of serial data between said signal processing module and a selected one of said plurality of line processing modules, and an interrupt controller for controlling said serial input/output interface, said data communication method comprising:

• a first communication process for connecting a communication path between the signal processing module and a corresponding line processing module via said serial input/output interface, assigning a communication time for communication between the signal processing module and the corresponding line processing module via said serial input/output interface, transmitting initial messages to the corresponding line processing module and simultaneously receiving a return message from said line processing module, when said communication time has elapsed transmitting a final message to the corresponding line processing module after the initial message has been transmitted, and executing service for the next line processing module when a final acknowledgment message is received from the corresponding line processing module;
• and
• a second communication process for receiving messages transmitted by said signal processing module via the communication path and simultaneously transmitting the return message to said signal processing module, and transmitting the final acknowledgment message to said signal processing module when the final message is received from said signal processing module.

A decentralized node exchange system of a telephone network comprising a plurality of subscriber terminals, said decentralized node exchange system comprising:

• a central processing module for controlling call switching in said decentralized node exchange system;
• a plurality of line processing modules connected to said plurality of subscriber terminals, for detecting communication data generated from said subscriber terminals;
• a communication path selector comprising a plurality of switches operably connected to corresponding ones of said plurality of line processing modules, for establishing communication path with said line processing modules;
• a signal processing module comprising a central processor for processing communication data generated in said decentralized node exchange system, a random-access memory for temporarily storing communication data, a read-only memory for storing application programs, a timer for performing a timer interrupt of said central processor, a serial input/output interface for enabling serial communication between said signal processing module and a selected one of said plurality of line processing modules, and an interrupt controller for controlling said serial input/output interface, said signal processing module establishing communication with said plurality of line processing modules by:
• forming a communication path with a first line processing module from said plurality of line processing modules by switching to a first switch of said communication path selector;
• assigning a communication time for communication between said signal processing module:
• and said first line processing module;
• transmitting initial messages from said signal processing module to said selected one of said plurality of line processing modules via said serial input/output interface, and simultaneously receiving a return message from said first line processing module via said serial input/output interface;
• after said initial messages have been transmitted and when said communication time has elapsed transmitting a final message from said signal processing module to said first line processing module via said serial input/output interface;
• and
• executing service for a second and next line processing module by switching to a second switch of said communication path selector when a final acknowledgment message is received from said first line processing module via said serial input/output interface.