Installation manual
CNC 8055
CNC 8055i
AXES CONTROLLED FROM THE PLC
14.
SOFT: V02.2X
·587·
PLC execution channel
14.1.3 Control of the PLC program from the CNC
The section of the PLC program regarding the "axes controlled from the PLC" can be controlled from
the CNC itself.
To do this, the inputs, outputs, marks, registers, timers or counters of the PLC itself are used.
The CNC has the following PLC related variables to read or change the status of the selected
resource.
PLCI To read or modify up to 32 PLC inputs.
PLCO To read or modify up to 32 PLC outputs.
PLCM To read or modify up to 32 PLC marks (internal relays).
PLCR To read or modify the status of a register.
PLCT To read or modify the count of a timer.
PLCC To read or modify the count of a counter.
With these variables, the desired values will be assigned, in the part-program of the CNC, to the
PLC resources used in the communication. The setting of these values will be carried out whenever
an axis or axes are to be controlled from the PLC.
In turn, the PLC program must check the status of such resources and when detecting that one of
them is activated, it must execute the corresponding section of the PLC program.
It is also possible to transfer data from the CNC to the PLC via global and local arithmetic parameters.
The PLC has the following variables related to those CNC parameters:
GUP To read or modify a global parameter of the CNC.
LUP To read or modify a local parameter of the CNC.
Sample
The "U" axis is controlled by the PLC and we want to command it from any part-program of the CNC
in such way that we could select the type of move (G00 or G01), the positioning coordinate and the
feedrate for that move.
In order to command it from any part-program, it is convenient to have in a subroutine the section
of the CNC program allowing the data transfer with the PLC.
This example uses subroutine SUB1 and, for data exchange, it uses global CNC parameters.
P100 Type of move. If P100 = 0, then G00; If P100 = 1, then G01.
P101 "U" axis positioning coordinate.
P102 Feedrate. It only makes sense when moving in G01.
To indicate to the PLC that it must execute this move, it activates the following PLC resource:
M1000 Command to begin movement.
Any part-program of the CNC may contain a block of the type:
(PCALL 1, G1, U100, F1000)
This block calls subroutine SUB1 and it transfers the local parameters G, U and F with the following
information:
G Type of move.
U "U" axis positioning coordinate.
F Feedrate for the movement.
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