RS-232 (Recommended Standard 232, also known as EIA/TIA RS-232C) is an interface that designates a standard for the exchange of a series of binary data between a DTE (Data Terminal Equipment) and DCE (Data Communication Equipment , Data Communication Equipment), although there are others in which the RS-232 interface is also used. An equivalent definition published by the ITU is called V.24. The RS-232 is a connectorDB-25 type (25-pin), although it is normal to find the version of 9-pin (DE-9, or popularly also called DB-9), cheaper and even extended to certain types of peripherals (such as serial mouse PC).

Parallel cable is the cable for computers defined by the IEEE 1284 standard for connecting peripherals via the parallel port. It is often used for connecting printers compatible PC computers. It is considered an outdated connection and has been replaced by USB. - IEEE 1284 Type A: 25-pin DB-25 IEEE 1284 - IEEE 1284 Type B: 36 Drivers, Champ type Centerline Connector 0.085 insurance (Centronics). - IEEE 1284 Type C: 36 conductors, connector type mini Champ de Centerline 0.050 with secure clip (mini Centronics).

If we talk about industrial automation we will find different terms related to the design of the internal circuit and the type of transmitter. PNP and NPN are two so-called bipolar or called (BJTs) transistors. These transistors that are controlled by current allow basically the amplification of the same through the circuit. Both PNP and NPN have the same function, provide amplification of the currentAnd/or switching. The only difference between them is the way in which the current or energy is assigned to each of its connectors.

• PNP (sinking or Pointing iN Proudly) is one of the types of transistors most used in electrical circuits, this type of transistor differs in that it receives positive voltage at its emitter terminal and negative voltage at its base terminal. Positive voltage to the transmitter allowsThe current flows from the emitter to the collector, since there is negative current to the base. As the voltage goes down from the base the transistor is on and conducts through the power at the output load.
• NPN (Sourcing or Not Pointing iN) is another transistor, unlike the PNP it is faster in its switching, since it works with reference 0V, it has less immunity to the noise and a smaller fall of tenZion. This type of transistor works in a completely opposite way to PNP. The NPN transistor receives positive voltage at the collector terminal. This positive voltage allows current to flow through the collector to the emitter, as there is enough base voltage to power the transistor. As the current increases at the base, the transistor is activated more and more until it is completely driven from the collector to the emitter and encoderGo the circuit. The opposite happens when the voltage decreases from the base, until the current is so low that the transistor no longer leads through the collector to the emitter and shuts off.