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Unformatted text preview: Year 2010 Month 11 Day 10 Data Communication Experiment Aerospace Engineering Laboratory II Name : Martin Suhartono Student ID : 20106182 Martin Suhartono -20106182 Page 2 1. Objective To understand the effect of changing communication speed on the signals of RS 232 communication system. 2. Introduction RS-232 (Recommended Standard 232) is basically a standard for serial binary single-ended data and control signals between Data Terminal Equipment (DTE) and Data Circuit- terminating Equipment (DCE). The standard generally defines the timing, characteristic and meaning of the electrical signal as well as the size of the connector. Electronics Industries Association (EIA) has defined the RS-232C to contain firstly, the electrical signal characteristic such as the voltage level or slew –rate of signals. It also requires the identification of pluggable connectors and pin as well as the interface mechanical characteristic in general. Additionally, there must be a mention of the functions of each circuit in the interface connector as well as the standard subsets of the interface connector. The standard however does not define the character encoding and the transmission bit rate. These properties are thus determined by the serial port hardware used in the communication. Due to the usage of the RS-232 that has extended beyond simple modem, the standard as depicted by EIA has also undergone several revisions. For example, the standard has now stated that the single-ended signaling referred to a common signal ground limits the noise immunity and transmission distance. In a personal computer, the RS-232 uses the DE-9 pin as the connector. The DE-9 pin is more compact and less costly than the recommended 25-pin D-type connector. The roles assigned to each pin are readily available in graphs and tables. For the case of the DE-9 pin connector, the roles are as follow: Pin no. Signal Pin no. Signal Pin no. Signal 5 Common Ground (Gnd) 4 Data Terminal Ready (DTR) 8 Clear To Send (CTS 3 Transmitted Data (Tx) 6 Data Set Ready (DSR) 1 Carrier Detect (DCD) 2 Received Data (Rx) 7 Request to Send (RTS) 9 Ring Indicator (RI) Sometimes, not all the pins are used in the data transmission. In fact, it is possible to utilize only three pins: no.5, 3 and 2 to make a successful communication. Nowadays, however, the serial port has been replaced mainly by the Universal Serial Bus (USB) for local communication. USB is faster, simpler to connect and uses lower voltage. USB is designed to be easier for the device drivers to communicate with the hardware. This then requires more complex software than the RS-232 and thus there is no direct analog to the terminal programs to let user communicating directly with the serial port. This renders the RS-232 to be useful in controlling various hardware devices like lamps or relay through personal Martin Suhartono -20106182...
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- Spring '12
- Serial port, baud rate, RS-232, Martin Suhartono