How to draw pressure relay coil in plc ladder diagram

The steps of converting relay circuit diagram into PLC external wiring diagram and ladder diagram with the same function are as follows:

1) Understand and be familiar with the working principle, process flow and mechanical action of the controlled equipment, and analyze and master the working principle of the control system according to the relay circuit diagram.

Reason.

2) Determine the input signal and output load of PLC. If the actuators such as AC contactor and solenoid valve of relay system are controlled by the output bit of PLC, they

The coil of is connected to the output end of PLC. Buttons, operating switches and travel switches, proximity switches, pressure relays, etc. Provide digital input signal of PLC. relay

The functions of intermediate relay and time relay (such as KA 1 and KT) in the system are completed by the storage bits and timers in PLC, which reflects the progress of PLC.

Such as input/output bits.

3) Select the model of PLC, select CPU module, power module and digital input/output module according to the required function and scale of the system, and group the hardware.

Status, determine the installation position and starting address of the input/output module in the rack.

4) Determine the addresses of input bits and output bits corresponding to each digital input signal output load of PLC, and draw the external wiring diagram of PLC. Each input and output

The addresses in the ladder diagram depend on the starting address of the module where they are located and the terminal number in the module.

5) Determine the storage bit (M) and address of timer and counter in ladder diagram corresponding to intermediate relay and time relay in relay circuit diagram. 4)

Step 5) and 5) establish the corresponding relationship between the components in the relay circuit diagram and the programming components in the ladder diagram.

6) Draw ladder diagram according to the above correspondence and relay circuit diagram.