1 -7
g
Node: The connection point between two or more elements
（
please refer to section 5.3
）
h
Block: a circuit consists of two or more elements.
There are two basic types of blocks:
•
Serial block
：
Two or more elements are connected in series to form a single row circuit.
Example:
•
Parallel block: Parallel block is a type of a parallel closed circuit formed by connecting elements or serial blocks in
parallel.
Example:
Remark: Complicated block can be formed by the combination of the single element, serial blocks and parallel
blocks. When design a Ladder Diagram with mnemonic entry, it is necessary to break down the circuits into
element, serial, and parallel blocks. Please refer to section 1.5.
i
Branch: In any network, branch is obtained if the right side of a vertical line is connected with two or more rows of circuits.
Example:
Branch
Merge line is defined as another vertical line at the right side of a branch line that merges the branch circuits into a
closed circuit (forming a parallel block). This vertical line is called “Merge line”.
Branch line
Merge line
If both the right and the left sides of the vertical line are connected with two or more rows of circuits, then it is both a
branch line and a merge line as shown in the example below.
Example:
Parallel block 1
Parallel block 2
Block 1 merge line
Block 2 branch line
