HEIDENHAIN TNC 426 CB, Technical Manual

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December 2001 PLC Functions 7 – 3
7 PLC Programming
7.1 PLC Functions
The integrated PLC of the TNC contains its own text editor for creating the list
of statements for the PLC program. You enter PLC commands and comments
through the TNC keyboard. It’s easier, however, to create your PLC programs
on a PC with the PLC compiler software
PLCdesign. For more information on
PLCdesign, contact HEIDENHAIN.
To prevent errors in the PLC program, the TNC operates a syntax monitor
during program input. The TNC assists you with the COMPILE function, which
checks the PLC program for logical errors, and the TRACE and TABLE
functions, with which you can check the condition of the operands.
The process memory runs a compiled PLC program up to a certain size (as of
280 474-10: 512 KB; 280 472-xx: 256 KB; 280 470 470-xx: 128 KB). Every
21 ms—the PLC cycle time—the TNC begins a new PLC scan, i.e. every 21
ms the inputs are reread and the outputs are reset. The PLC cycle time can be
set with MP7600.1 and ascertained with Module 9196. For a PLC cycle time
of 21 ms, a PLC scan must not take more than 10 ms.
Module 9196 Finding the PLC cycle time
The PLC cycle time is determined in ms.
Call:
CM
9196
PL D <PLC cycle time in ms>
MP7600.1 PLC cycle time
= MP7600.1 * Position controller cycle time
= MP7600.0 * MP7600.0 * 0.6 ms
Input: 1 to 20 (recommended input value: 7)
7.1.1 Selecting the PLC Mode
In PLC mode you can:
n
Create (and test) PLC programs
n
Write PLC error messages
n
Write dialog texts for OEM cycles
n
Create help files
n
Create compensation value lists for nonlinear axis error compensation
Select PLC Mode:
7 7 7 7 Select the Programming and Editing mode of operation.
7 7 7 7 Press the MOD key.
7
7 7
7 Enter the code number 807 667 and confirm your entry with the ENT key,
or if you already entered the code number, press the PLC EDIT soft key.
Exit PLC mode:
7 7 7 7 Press the END hard key or soft key.