More Advanced Programming; Applied Instructions Reference - Mitsubishi MELSEC System Q Manual

More Advanced Programming

6 More Advanced Programming
The basic logic instructions listed in Chapter 3 can be used to emulate the functions of a
hard-wired contactor controller with a programmable logic controller. However, this only
scratches the surface of the capabilities of modern PLCs. Since every PLC is built around a
microprocessor they can also easily perform operations like mathematical calculations, com-
paring numbers, converting from one number system to another or processing analog values.
Functions like these that go beyond the capabilities of logic operations are performed with spe-
cial instructions, which are referred to as applied or application instructions .
6.1

Applied Instructions Reference

Applied instructions have short names that are based on the English names of their functions.
For example, the instruction for moving 16-bit data is called MOV.
When you program an applied instruction you enter the instruction name followed by the
device name. The following table shows all the applied instructions currently supported by the
MELSEC System Q family of controllers. This list may look a little overwhelming at first, but
don't worry – you don't have to memorise them all! When you are programming you can use the
powerful Help functions of GX Developer and GX IEC Developer to find the instructions you
need. In this chapter we will only cover the more frequently-used instructions, which are
shown with a grey shaded background in the reference table. For full documentation of all the
instructions with examples please refer to the Programming Manual for the A/Q series and the
MELSEC System Q, art. no. 87431.
NOTE Many applied instructions can be executed cyclical or pulse triggered (with the rising edge of
the input condition). In this case the name of the instruction is suffixed by the letter "P". For
example: MOV -> execution in each program cycle as long as the input condition is true;
MOVP -> one-time execution on the rising edge of the signal pulse generated by the input
condition.
Category
Comparison
operations
MELSEC System Q Beginners Manual
Instruction
LD=
LD>
LD<
LD<>
LD<=
LD>=
AND=
AND>
AND<
Compare 16-bit data
within operations
AND<>
AND<=
AND>=
OR=
OR>
OR<
OR<>
OR<=
OR>=
Applied Instructions Reference
Function
Compare for „equals"
Compare for „greater than"
Compare for „less than"
Compare for „not equal"
Compare for „less than or equal to"
Compare for „greater than or equal to"
Compare for „equals"
Compare for „greater than"
Compare for „less than"
Compare for „not equal"
Compare for „less than or equal to"
Compare for „greater than or equal to"
Compare for „equals"
Compare for „greater than"
Compare for „less than"
Compare for „not equal"
Compare for „less than or equal to"
Compare for „greater than or equal to"
6 – 1