D20 - Nc And Plc Synchronization - HEIDENHAIN TNC 640 User Manual

10
D20 – NC and PLC synchronization
Danger of collision!
Changes to the PLC can result in undesired behavior and
serious errors (e.g., inoperability of the control). For this reason,
access to the PLC is protected by password. The FN function
provides HEIDENHAIN as well as your machine tool builder and
suppliers the ability to communicate with the PLC from an NC
program. It is not recommended that the machine operator or
NC programmer use this. There is risk of collision during the
execution of the function and during the subsequent processing!
Only use the function in consultation with HEIDENHAIN, the
machine tool builder, or the supplier.
Comply with the documentation from HEIDENHAIN, the
machine tool builder, and suppliers.
With the D20 function you can synchronize the NC and PLC during
a program run. The NC stops machining until the condition that you
have programmed in the D20 block is fulfilled.
SYNC is used whenever you read, for example, system data via
D18 that require synchronization with real time. The control stops
the look-ahead calculation and executes the following NC block only
when the NC program has actually reached that block.
Example: Pause internal look-ahead calculation, read current
position in the X axis
N32 D20 SYNC
N33 D18 Q1 ID270 NR1 IDX1*
426
NOTICE
Programming Q Parameters | Additional functions
HEIDENHAIN | TNC 640 | ISO Programming User's Manual | 10/2017