how to get a signal PLC ladder program

PLC programming often need to use different commands to obtain different information on the switch
this is plc programming examples

1. Get information on the rising edge

To obtain information on the rising edge of the input signal by the transition instruction, contacts and trigger rising edge pulse

2. Get information falling edge

To obtain information on falling edge the input signal drops by contact and falling edge pulse trigger

3. Get level information

     If the button corresponding to the input port is normally open, the program can be obtained through a high level of information normally open contact, normally closed contact information to obtain Low level