How many input and output does a PLC have?
A PLC interfaces numerous types of external electrical and electronic signals.
These signals can be AC or DC currents or voltages.
Typically, they range from 4 to 20 milliamperes (mA) or 0 to 120VAC, and 0 to 48VDC.
These signals are referred to as I/O (input/output) points..
How does a PLC read analog input?
When the analog input signal enters the PLC it goes through an A/D converter or analog to digital converter. This is the component in the PLC analog input card that transforms the analog signal to digital signals. It is these digital signals that will eventually give our binary value representation in the PLC.
What are the 4 main components of a PLC?
The basic components include a power supply, central processing unit (CPU or processor), co-processor modules, input and output modules (I/O), and a peripheral device.
How does a PLC input card work?
The I/O system provides the physical connection between the equipment and the PLC. Opening the doors on an I/O card reveals a terminal strip where the devices connect. There are many different kinds of I/O cards which serve to condition the type of input or output so the CPU can use it for it’s logic.
What is a PLC output?
PLC outputs are of two general types: (1) relay. (2) solid state. Relay outputs are mechanical contacts and solid state outputs may take the form of transistor or TTL logic (DC) and triac (AC). Relay outputs are usually used to control up to 2 amps or when a very low resistance is required.
How do you check PLC inputs and outputs?
If the PLC processor has an AC power source, check the input voltage; it should be within the manufacturer’s recommended range. PLC processors actually operate on DC power, so that also must be checked. Measure each of the outputs of the DC power supply and check if the voltages are within the recommended ranges.