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Chapter Four PLC Basis Code
23
Volume I
Programming
CHAPTER FOUR PLC BASIS CODE
The design of the sequence program begins from compiling ladder diagram. The ladder
diagram consists of relay contact and function code. The logic relationship in the ladder diagram
composes of sequence program. There are two methods of the sequence program input: one uses
the mnemonic symbol language (The system is not temporarily supported the PLC command code
of the RD, AND and OR); the other one is used the relay symbol. The programming can be compiled
using ladder diagram instead of comprehending the PLC code based upon the latter.
Actually, the sequence program inside the system can be converted into corresponding PLC
code even if it is input by the relay symbol.
The basis codes are commonly used one when designing the sequence programming, which
are performed one-digit calculation.
The basis command codes of the GSK218MC series are shown below:
Table 4-1
Code name
Function
RD
Left shift 1-bit of the register’s content, the signal state specified by address is set to
ST0
RD.NOT
Left shift 1-bit of the register’s content, the signal state specified by address is set to
ST0 after its state is set to NOT.
WRT
Output the logic calculation result to the specified address
WRT.NOT
Output the logic calculation result after NOT to the specified address.
AND
Logic AND
AND.NOT
Logic AND after the specified state is set to NOT.
OR Logic
OR
OR.NOT
Logic OR after the specified state is set to NOT.
OR. STK
Right shift 1-bit of the stacked register after ST0 and ST1 logic OR
AND.STK
Right shift 1-bit of the stacked register after ST0 and ST1 logic AND
4.1 RD, RD.NOT, WRT, and WRT.NOT Codes
Mnemonic symbol and function
Table 4-1-1
Mnemonic
symbol
Function
RD
Left shift 1-bit of the register’ content, the signal state specified by address is
set to ST0.
