This Method of Data Transmissioninvolves transmission of data, character by character at a time. These characters are transmitted and controlled using start and stop bits. Every character is enclosed between start and stop bits. Every character is enclosed between start and stop bits. At the receiving end, these characters synchronize to complete the data transfer. This transmission is usually slow, but it less expensive method of data transmission.
Different Modes of Data Transmission
The data can be transmitted in one of the following modes
Simplex Transmission Mode
At the receiving end, these characters synchronize to complete the data transfer. This transmission is usually slow, but it less expensive method of data transmission.
In this Mode of Data Transmission, the data can be transmitted in one direction only i.e. one can either send the data transmission is not preferred as one to get the acknowledgement of the data transmitted, or error signals have to be transmitted back, which all require a return path. The following figure illustrates the simplex mode of data transmission.
Half Duplex Transmission Mode
In this mode of data transmission, the data can be transmitted in either direction but not at a given point of time i.e. we cannot have two way data transmission simultaneously. The following figure illustrates Half Duplex Mode of Data Transmission.
Full Duplex Transmission Mode
In this mode of data transmission, the data can be transmitted in both the directions at any given point of time i.e. one can have simultaneous data transmission in either directions. This is the most preferred form of transmission mode, as it is faster and time is saved as data from either direction flows at the same instance of time.
Communication Channel Configurations
For establishment channels, i.e. communication lines, the following are two basic configurations, either of which is used to establish a Communication Channel.
Point to Point
This is quite a simple channel configuration, where the units/devices/computers to be connected, use dedicated communication lines i.e. the connection is established using –direct lines which connect the devices to other devices. Usually, these communication channels are under-utilized, as the terminal or the device which uses this channel, may not be that active, which is required to keep the line busy. This also involves high cost, as for every connection, one need to have separate cables. These lines will be relatively faster, as the traffic would be very less. This Configuration of Communication Channel is not that, popular owing to its costs and, under utilization. The figure illustrates the point to point channel configuration.
Multi-Point Channel Configuration
This Configuration of Communicationchannel has evolved, to remove the short comings of point to point channels of under-utilization and cost. In these channel comings two or more devices/terminals/computers are connected using a single line. This facilities the optimum utilization of the communication channel as any of the devices or some or all the devices connected to the line will be active enough to keep the line busy, as well as there can be communication between the devices.
This configuration is more efficient on the utilization and cost fronts, as it is utilized to the optimum level and the cost is less owing to single cable, which reduces interacting. For the obvious reasons, this communication channel configuration is widely used and adopted.
To improve Efficiency of the Communication Channelson the performance and cost point of view, various techniques, processors etc, are used, especially, when the data is transmitted in digital form.