Chapter 16 PLC Function ApplicationsC2000 Plus 
 
16-19
Explanation of basic structure of ladder diagrams   
1.  LD (LDI) command: An LD or LDI command is given at the start of a block.   
 
LDP and LDF have this command structure, but there are differences in their action state. LDP, LDF 
only act at the rising or falling edge of a conducting contact. (see figure below):   
 
2.  AND (ANI) command: A series configuration in which a single device is connected with one 
device or a block.   
 
ANDP, ANDF also have structures like this, but their action occurs at the rising and falling edge.   
3.  OR (ORI) command: A single device is connected with one device or a block.   
 
ORP, ORF also have identical structures, but their action occurs at the rising and falling edge.   
4.  ANB command: A configuration in which one block is in series with one device or block.