Fagor CNC 8065 - Chapter 10 Cnc Variables; Understanding How Variables Work

CNC 8060
CNC 8065
(REF: 1402)
10
·527·
CNC VARIABLES.
10.1 Understanding how variables work.
Accessing the variables.
The internal CNC variables may be accessed from the part program, MDI/MDA, PLC and
from any application or external interface (for example FGUIM). Each variable must indicate
whether it can only be read or read and written.
Access the variables from a part-program. Accessing during execution or during
block preparation.
The CNC reads several blocks ahead of the one being executed in order to calculate in
advance the path to follow. This prior reading is known as "block preparation".
The CNC checks certain variables during block preparation and others during execution. The
variables that use the execution value interrupt block preparation temporarily and the CNC
resumes it when it is done reading/writing the variable. Accessing the variables from the PLC
or from an external interface never interrupts block preparation.
Be careful with the variables that interrupt block preparation because when they are inserted
between machining blocks with compensation may cause undesired profiles. Interrupting
block preparation may result in compensated paths different from the one programmed,
undesired joints when working with very short moves, etc.
In any case, it is possible to use the #FLUSH instruction to force the evaluation of a variable
when it is being executed. This instruction interrupts block preparation in advance, executes
the last prepared blocs, synchronizes the preparation and execution of blocks and then goes
on with the execution of the program and block preparation.
Accessing the variables. from the PLC. Synchronous or asynchronous access.
PLC access to the variable, both for reading and writing, may be either synchronous or
asynchronous. A synchronous access is resolved immediately whereas an asynchronous
access takes several PLC cycles to resolve.
The tool variables will be read asynchronously when the tool is neither the active one nor
in the magazine. The tool variables will be written asynchronously whether the tool is the
active one or not.
Example of how to access asynchronous variables.
Reading of the radius value of offset ·1· of tool ·9· when it is not in the tool magazine.
<condition> AND NOT M11 = CNCRD (TM.TORT.[9][1], R11, M11)
The PLC activates mark M11 when the operation begins and keeps it active until the operation
ends.
DFD M11 AND CPS R11 EQ 3 = ···
It waits for the consultation to end before evaluating the data.