PLC input port and output port connection introduction and common type -

by:Coolmay     2020-07-07
At present, PLC in industrial production and automation control utilization rate is very high concentration of control equipment, PLC to replace the heavy ark of relay, ac contactor cabinet, etc. , gradually widespread use in the production and control. The design of PLC control system, although small in proportion of wiring work, most of the work or the PLC programming design work, but it is the foundation of programming design, as long as the correct wiring, can smoothly programming design work. PLC correct connection is the premise condition of PLC function, skilled master PLC input port and output port connection is necessary for every power operation personnel.

usually, PLC AC220V power input end, is to run the PLC power supply. PLC output power port for DC24V commonly, is the power output of PLC. PLC in use process, the input and output it is very important to the correct wiring, wiring is the precondition of PLC to work correctly.

let's focus to analyze the input terminal of PLC, the output end of the common connection type:

a, the input port of the common connection types and object:

PLC input port is usually input:

1, on-off signals:

button, trip switch, switch, proximity switch, dial the code switch and so on.

simple example easier to say:

button or proximity switch wiring is shown in: PLC switch wiring, and a head of access to the input end of the PLC ( X0, X1, X2, etc. ) Together, on the other side and public access to the PLC controller port ( COM) 。

2, analog signals:

generally for various types of sensors, such as: pressure transmitter, liquid level transmitter, remote transmission pressure gauge, thermocouple and thermal resistance, and so on.

analog signal acquisition device, equipment wire ( Two wire or three wire system) Different wiring methods will be slightly different. As shown in figure:

two, output port connection.

PLC output port connection generally can be divided into the following three conditions:

1, the relay output.

2, transistor output.

3, thyristor output.

PLC output in a different way, the power of the output load that type is also different. As shown in figure: this is input and the output of PLC basic wiring, belong to the basic knowledge of PLC.

three, three common sense in the process of PLC wiring:

1, PLC, power supply circuit.

PLC control system of power supply in addition to the ac power, dc power supply also includes PLC, in general, PLC, ac power can directly by the mains supply, and input devices ( Switches, sensors, etc. ) Dc power supply, and output devices ( Relay) The dc power supply, etc. , had better take independent dc power supply. Most of the PLC with 24 v dc power supply, current is needed only when the input or output devices are not a lot of cases, to use the PLC with dc power supply.

2, and the PLC input port and output current rating.

input port of PLC with general for DC24v power supply, input port of each point in 5 ma - current quota Between 7 ma, the electric current is generated when the input port short after the maximum current, when the input port has the certain load, the flow of current will be reduced correspondingly. PLC input signal passing the required minimum current is commonly 2 ma, in order to ensure the effective minimum input current signal, pick up equipment total impedance input port is normally less than 2 k.

that is to say, when the input port of the sensor power is bigger, need to pick up a separate external power supply.

3, PLC output port can generally by the maximum current varies with PLC models, most between 1 a and 2 a, when the load current is greater than the PLC port when the maximum rated current, generally need to increase the intermediate relay connect the external contactor or other equipment.

PLC correct wiring is the precondition of effective operation of PLC controller, PLC basic skills, skilled master PLC wiring common sense is very necessary.


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