Ladder Diagram; Program Scan Chart Of The Plc Ladder Diagram - Delta C2000 series User Manual

16.3 Ladder Diagram

16.3.1 Program Scan Chart of the PLC Ladder Diagram

Calculate the result by
ladder diagram
algorithm (it doesn't
sent to the outer output
point but the inner
equipment will output
immediately.)
16.3.2 Ladder Diagram
Ladder diagram is a diagram language that applied on the automatic control and it is also a
diagram that made up of the symbols of electric control circuit. PLC procedures are finished after
ladder diagram editor edits the ladder diagram. It is easy to understand the control flow that
indicated with diagram and also accept by technical staff of electric control circuit. Many basic
symbols and motions of ladder diagram are the same as mechanical and electrical equipments of
traditional automatic power panel, such as button, switch, relay, timer, counter and etc.
The kinds and amounts of PLC internal equipment will be different with brands. Although internal
equipment has the name of traditional electric control circuit, such as relay, coil and contact. It
doesn't have the real components in it. In PLC, it just has a basic unit of internal memory. If this bit
is 1, it means the coil is ON and if this bit is 0, it means the coil is OFF. You should read the
corresponding value of that bit when using contact (Normally Open, NO or contact a). Otherwise,
you should read the opposite sate of corresponding value of that bit when using contact (Normally
Closed, NC or contact b). Many relays will need many bits, such as 8-bits makes up a byte. 2
bytes can make up a word. 2 words make up double word. When using many relays to do
calculation, such as add/subtraction or shift, you could use byte, word or double word.
Furthermore, the two equipments, timer and counter, in PLC not only have coil but also value of
counting time and times.
Read input state from outside
X0 X1
Start
Y0
X10
M100 X3
:
:
X100 M505
Send the result to the output point
16-9
Chapter 16 PLC Function |C2000 Series
Y0
Repeats the
Y1
execution in
cycle.
Y126
End