PLC Control DC Amplifier Board 16Channel Anti - Interference Circuit With Heat Sink

PLC Control DC Amplifier Board 16Channel Anti - Interference Circuit With Heat Sink

PLC output circuit is generally divided into: relay output, transistor output and thyristor output three. Understanding the differences between these three output forms is very necessary for the hardware design of the PLC. The following takes Mitsubishi PLC as an example to briefly introduce the differences and precautions of the three output circuit types. The PLC output circuits of other companies are similar in form.

1, the transistor output circuit

The transistor output circuit is faster than the relay output (usually less than 0.2ms) and is suitable for applications requiring fast response. Since the transistor has no mechanical contacts, it has a longer life than the relay output circuit.

The external power supply of the transistor output circuit can only be a direct power supply, which is one aspect of its application limitations. In addition, the transistor output drive capability is less than the relay output, allowing the load voltage is generally DC5V ~ 30V, allowing the load current is 0.2A ~ 0.5A. These two points should be taken care of when using transistor output circuit types.

There are two main types of transistor output circuits: NPN and PNP open collector outputs.

The common terminal COM of the open collector output type of the NPN type can only be connected to the negative terminal of the external power supply, while the COM terminal of the PNP type can only be connected to the positive terminal of the external power supply.

In the same way as the relay output circuit, when the inductive load is driven, an anti-parallel diode (the cathode of the diode is connected to the positive pole of the power supply) must be connected at both ends of the load to prevent overvoltage and protect the output circuit of the PLC.

Relay output circuit

This is a common form of PLC output circuit. The external power supply of the output circuit can be either DC or AC.

PLC relay output circuit type allows the load is generally AC250V/50V, load current up to 2A, capacity up to 80 ~ 100VA (voltage × current), therefore, the PLC output is generally not directly driven high-current load (usually through a small load To drive a large load, such as the PLC output can be connected to a relatively small current relay, and then by the intermediate relay contacts to drive large loads, such as contactor coils, etc.).

PLC Relay Output Circuit Form Relay contact life is also limited (usually hundreds of thousands of times, depending on the load, such as the connection of inductive load life than the resistive load). In addition, the response time of the relay output is also slow (about 10ms). Therefore, it is not suitable to use this kind of circuit output form when the fast response is required (you can use the two output formats described below depending on the occasion).When connecting an inductive load, in order to extend the service life of the relay contact, for the case of an external DC power supply, an overvoltage suppression diode should normally be applied across the load (a diode in the external relay coil as shown above and in the diagram); For load, an RC suppressor should be added to both ends of the load.

♦ Features

-- Standard DIN rain mounted

-- Status indication for each input

-- Special circuit for self test and anti-interference

-- High quality MOSFET with large load and excellent stability

♦ Typical Applications

• Micro-controller • PLC control • Servo System

• Electro-magnetic valve • DC Motors

• Home intelligent control

♦ Technical data