RS232

RS232 standard set by the Electronic Industry Association and Telecommunications Industry Association in 1962. His full name is EIA/TIA-232 Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange. Although his name is quite long but this standard is only concerned with data communication between computer equipment computer peripherals. There are two main things that set the standard RS232, among other things:

• The shape and signal voltage levels are used.

RS232 built in 1962, long before the popular TTL IC, therefore the voltage levels specified for RS232 nothing to do with TTL voltage levels, it can even be said that different. Here's the difference between RS232 and TTL voltage levels:

Determination of types of signals and connectors that are used, as well as the arrangement of the signal at the legs of the connector. Some parameters are defined EIA (Electronics Industry Association •), among others:

• A 'space' (logic 0) voltage between +3 s / d +25 volt
• A 'sign' (logic 1) voltage between -3 s / d -25 volt
• Local voltage between +3 s / d -3 volts is not defined
• open circuit voltage should not exceed 25 volts (with reference to ground)
• short circuit current of the circuit should not exceed 500 mA.

A driver (drivers) should be able to handle this current without damage. In addition to describing the voltage levels as discussed above, standard RS232 determine the types of signals are used to set the exchange of information between the DTE and DCE, are all there are 24 types of common signals but that is only 9 types of signals. Connectors used were determined in a standard RS232, for a complete signal used DB25 connectors, while the DB9 connector can only be used for commonly used signal 9.