Tag Archives: PLC ladder

What time relay is used for Mitsubishi PLC power-off delay

Mitsubishi does not have a power-off delay to close the relay. Only the power-on delay closes the relay, but it can be implemented by a program.

as the picture shows,
When X0 is ON,
M0 reset,
M0 is disconnected in front,
T0 does not count,
When X0 becomes OFF,
M0 is set and T0 starts counting.
Time is up,
When the contact T0 is output, the function of closing the power-off delay is reached.

How to use the gx developer timer to time one hour

Use two timer relays, first make a half-hour timer, 18000X0.1=1800 seconds, this timer will trigger an M point again, use this M point to trigger another half-hour timer again.

The most simple and safest delta voltage starting circuit diagram

circuit diagram

FX2N Series PLC data communication module

PLC communication module is used to complete with other PLC intelligent control, other communication between devices or computers. Following brief introduction to FX serial communication function expansion board, adapter and communication modules.


(1) communication expansion board FX2N-232-BD. FX2N-232-BD is to connect standard PLC and other RS-232C transport device interface board, such as personal computers, bar code reader, or printer. The panels can be installed inside the FX2N extension. The maximum transmission distance is 15m, the maximum baud rate for 19200bit/s. PLC using special software for the extension plate can be running monitoring, can also be transmitted from the PC to the PLC program.


(2) communication interface module FX2N-2321F. FX2N-2321F on connect FX2N series PLC can realize RS-232C with the other fullduplex serial communications interface devices, such as personal computers, printers, bar-code reading device and so on. FX2N series FX2N-2321F modules can connect up to 8 blocks. The module using FROM/TO command to send and receive data. Maximum transmission distance is 15m, the maximum baud rate for 19200bit/s. The modules take up to 8 I/O point. Data length and serial communication baud rate can be set by a special data register.


(3) communication expansion board FX2N-485-BD. FX2N-485-BD for RS-485 communication. It can be applied to no agreement on data transfer, FX2N-485-BD at the time of the original agreement, as a way, using RS instruction in personal computers, barcode reader, printer, data transfer between. Transmitting maximum transmission distance is 50m, the maximum baud rate for 19200bit/s. Each of the FX2N series PLC expansion boards can be fitted with a FX2N-485-BD communication. In addition to using this communication expansion boards and computer communications, it can also be used to achieve two parallel between FX2N series PLC.


(4) communication expansion board FX2N-422-BD. FX2N-422-BD to RS-422 communications, can be connected on the FX2N series PLC, and as a tool for programming or control a port. This interface is available outside of the PLC connected to PLC devices, data storage unit, and human-machine interface. FX2N-422-BD can be used to connect two data storage unit (DU) or DUseries unit and a programming tool, but one can only connect a programming tool. Every basic unit can be connected to a FX2N-422-BD and cannot be used with FX2N-485-BD or FX2N-232-BD.


(5) the interface module MSLSECNET/MINI


Use MSLSECNET/MINI interface module, series PLC of FX series PLC can be used as a local control station, constitute a distributed control system.


Above on the FXseries only gives a brief introduction to the communication module, specific application again in detail in later chapters.

SIEMENS S7-300 PLC control 3 lights Turn on Programming examples

This is  siemens plc s7-300 Cycle execution  Programming examples

When the X0   on, the lamp Y0 on ; after 5S, the lamp Y0 off, the lamp Y1 on ; after 5S, the lamp Y1 off, the lamp Y2 on, and then after 5s , the Y2off, the lamp Y0 on, cycle….

plc ladder diagram

Siemens PLC S7-300 controls the motor to start up Ladder Diagram programming examples

Today we’ll make a plc ladder diagram for siemens plc s7-300 control the motor start up. plc ladder diagram  is very important to learn plc programming.
(1) Control requirements.
There are three motors M1, M2, M3, press the start button to start M1, M2 starts after delay 5s, M3 starts again after 16s.
(2) Programming element symbol address

Programming element symbol address

(3) PLC Ladder Diagram

PLC Ladder Diagram

PLC ladder programming sequence control

Learning PLC programming, we often encounter the sequential control, but how to make plc ladder diagram
there is  example Shuttle program.

The initial state of the car parked in the middle (limit switch X0 is pressed, the normally open contact closure),Press the Start button (X3 closed), the car began to follow the direction shown to reciprocate when you need to stop, press the stop button (X4 closed), stop automatically when the car moves to the middle position. Here all the buttons and travel switches are normally open contacts are connected to the input terminals of the relay.

how to program long delay PLC ladder diagram

When plc programming often need several hours, or even longer delay, the best way is  series timer, or  PLC internal counter.Using the timer series Can be a long delay, in essence, it is to allow multiple timers turn ON, delay time is Accumulating multiple timer settings.

Serial time delay

Set time of the timer T1 is a counter C100 input pulse signal, so that the delay time is several times of  T1 setpoint.

Timers and counters associated with long time delay
The internal special relay R901E (1 min clock) as the counter C100 input signal, so that the time delay is a few minutes. If a counter does not meet the requirements, the counter can be used in series, that is, the contact of the front counter is used as the input pulse signal of the back of a counter to achieve a longer time delay.
Counter long time delay

how to program Power Delay on and Power loss delay off PLC ladder diagram

When the X0 is turned on, the timer T1 starts to delay, after 2S Timer T1 normally open contact closure (set point signal), hold instruction make the Y0 power and hold; When the X0 is off, the timer switch on T2 (normally open contacts at Y0) start delay, 4S timer T2 normally open contacts (reset signal), Y0 power loss

 http://www.plchelpcenter.com/2016/07/11/how-to-program-power-delay-on-and-power-loss-delay-off-plc-ladder-diagram.html

Siemens S7-300 plc programming examples pulse generator

Timer may constitute a pulse generator with two timers generate a pulse duty cycle of the signal frequency can be set. When the input I0.0 is 1, Output Q0.0 is 0 or 1 alternately
Periodic pulse signal for 3s, the pulse width is 1s.