Examples of the synchronization methods in connection with motions

Programming example

N05 M26 G00 X25  (M26, synchronization type MVS_SLP)
N10 M27      (M27, synchronization type MVS_SLP)
N20 X50
N30 X75
N40 X100
N50 G01 X125 F2000N60 #EXPL SYN     Triggering of M26, M27
before             execution of the next block
N70 G00 X0
N80 X0 Y0
M30

Behaviour of 'late' synchronization (MVS_SLM, MVS_SLP) at program end

The M function remains active even beyond the end of the CNC program if there is no feed motion block after programming of an MVS_SLM M-function or if there is no longer any #EXPL SYN in the current CNC program after programming of an M function with the synchronization method MVS_SLP. Synchronization then takes place in a subsequent CNC program when the trigger condition is reached.

Programming example

%PRG1
N05 M26 G00 X25     (M26, synchronization type MVS_SLM)
N10 M27         (M27, synchronization type MVS_SLP)
M30         (M26, M27 still active at the)            
(program end)
%PRG2
N10 G01 F100 X10   <--Triggering of M26 before              
execution of the motion
N20 #EXPL SYN      Triggering of M27 before execution          
of the next block
M30

If, when a CNC program is started, there are still pending M functions with a 'late' synchronization method from the previous CNC program, synchronization can fundamentally be forced here.

To this end, 1 must be assigned to the channel parameter P-CHAN-00033 (late_sync_ready).

Initialization in the channel parameter list

late_sync_ready 1

Programming example

%PRG1
N05 M26 G00 X25     (M26, synchronization type MVS_SLM)
N10 M27         (M27, synchronization type MVS_SLP)
M30         (M26, M27 still active at the)            
(program end)

%PRG2           <--Triggering and waiting for            
acknowledgement of M26, M27            
before starting of the program
N10 G01 F100 X10
M30

MET_SVS, MEP_SVS

Pre-output of the M function in accordance with a specified distance or time and motion enabling only after acknowledgement of the M function by the PLC.

Initialization in the channel parameter list

m_synch[..] 0x01000000 (synchronization MEP_SVS)
m_synch[..]0x02000000 (synchronization MET_SVS)

Programming example

N10 G01 X10 G90 F5000
N20     X20
N30     X30
N40     X40
N50     M96     (M96 MEP_SVS m_pre_outp = 250000,)            
(or MET_SVS m_pre_outp = 300000us)
N55     X80
N60     X0
M30

Defining the lead distance or time

The channel parameters P-CHAN-00070 (m_pre_outp[i]) and P-CHAN-00107 (h_pre_outp[i]) are used in combination with the synchronization types MET_SVS and MEP_SVS. The parameters define the value for output before execution of the M/H functions in the path interpolator. The lead time is specified in the case of the MET_SVS type and the lead distance in the case of the MEP_SVS type.

Example for an initialization in the channel parameter list for 2 M functions:

• The user-specific M function M96 is to be output to the PLC 10 millimeters before the synchronization position in the block sequence is reached
• The user-specific M function M97 is to be output to the PLC 40 millimeters before the synchronization time in the block sequence is reached

# Definition of M functions and synchronization methods

#======================================================
:
m_synch[96]           0x01000000    MEP_SVS
m_synch[97]           0x02000000    MET_SVS
#
# Pre-output time/distance setting with MET_SVS, MEP_SVS
#=======================================================
m_pre_outp[96]        100000    in 0.1 um
m_pre_outp[97]        40000     in us

In NC program the definition of path or time lead of each M/H function also can be changed by corresponding variables. (e.g. V.G.M_FCT[MNr].PRE_OUTP_PATH, see [PROG]).

MOS_TS

Output of the M function before NC block, no synchronization. With this type the CNC provides a sample time offset in reference to block transition point.

Because of motion profile sampling with cycle time t_zykl the output time of M-function in interpolator is in sample time raster but has at least an maximum time offset of one sample step in reference to the block transition point. The exact output timing can be calculated and done in the PLC by using the sample time offset of M code. (see also [HLI] , pMHTechno^.D_Time).

Initialization in the channel parameter list

m_synch[..] 0x00040000 (MOS_TS)

Programming example

N10 G01 X25 G90 F5000
N20     X50
N30     M25 (M25 MOS_TS)
N40     X100
N50     X200
M30

The output instant of the M code is in sample time raster but not exactly on block limits between the two motion blocks N20 und N40. For controlling the high accuracy output in the PLC, during calculation of the output instant the time offset t_cr (fractional part of sample time step, characterizes the exact position of sample time step in reference to block transition point) is considered.

The function for exact output instant is realized in PLC typically with use of specific high resolution timer hardware.

Programming example:Exact path synchronous triggering of I/Os

During cutting process a laser (beam width 100µm) shall be switched on/off on exact position. The tolerance is within 10 µs respectively within a ½ beam width (=50 µm). The time related resolution of the CNC interpolation cycle (typical 1 ms) is not sufficient. The problem can be solved by using a specific high resolution timer hardware.

In the system sequence CNC to drive the delay is defined greater than the delay in the system sequence to the laser system.

In the current case based on the laser system a typical delay of 800 µs is assumed. For the positioning sequence CNC – drive the typical delay is 5 sample cycles ((5 * 1 ms = 5 ms). The positioning system inside the drive operates without position lag (active feedforward control). However if necessary, the position lag can be estimated. The delay of the positioning sequence for the triggering of the laser is considered in PLC with time T_DPLC .

So the provided CNC based M code of the path interpolator is delayed for n cyles inside the PLC. The exact control signal for the laser in the following cycle is calculated within the PLC, based on the interpolation data and the delay and it is created on a hardware terminal with a high basic clock-pulse rate (e.g. 1µs).