NCT 90 User manual

NCT®90
MILLING-MACHINE CONTROL
INTEGRATED PCL

Manufactured by NCT Automation kft.
H1148 Budapest Fogarasi út 5-7
:Address: 1631 Bp. pf.26
FPhone: ([phone]
FFax:([phone]
E-mail: [email protected]

© Copyright NCT February 26, 2001
The Publisher reserves all rights for
contents of this Manual. No reprinting,
even in extracts, is permissible unless
our written consent is obtained.
The text of this Manual has been
compiled and checked with utmost care,
yet we assume no liability for possible
errors or spurious data and for
consequential losses or demages.

1
1 General Description
Apart from slide movements, the solution of technological functions require
$" the status of the machine-tool to be signalled to the control (functional conditions of
subassemblies, emergency states etc.),
$" the programmable commands (other than those referring to slide movements) to be
conveyed to the machine-tool.
This task is solved in most CNC controls by emitting or receiving signals of 24V, the
meanings of which are lays down in standard specifications. Those signals are coupled and
converted (to meet the needs of the particular machine-tool) by a relay-type logic circuit or
by a special-purpose equipment (PLC).
Those logic circuits will
$" interpret and combine the signals coming from the machine-tool,
$" decode the commands coming from the control, breaking them up into signal sequences
or dialogs,
$" performself-containedfunctionsusuallyrelatedwithtimefunctions(e.g.slidelubrication
cycles).
The NCT 90 controls transfer this logic function to the "integrated" PLC. The NCT controls
are operated in multi-task systems, in which basically four TASKS alternating at intervals
of 5 ms; thus a given task will be on after every 20 ms.
The PLC (Programmable Logic Control) is one of the four tasks. On its turn, the PLC task
is run invariably in the following manner.
1.1 Structure of the PLC Task
Activities in the PLC are:
1.1.1 System`s Activities
$" Sampling 24V INPUTs.
$" Managing TIMERs.
$" Emergency state established in the event of a short-circuited OUTPUT.
$" Monitoringthe readystate of the power supply (emergency state established in the event
of a trouble).
$" On every fifth turn (at intervals of 100 ms), the current spindle speed value is generated,
i.e. the programmed S is output, modified with the spindle override and with the
value of the DRIFT parameter.
$" Updating the 24V outputs at the end of the PLC time slice.
1.1.2 Execution of the Module :001
This "fast" module is called every 20 ms; it must be completed in the available (PLC) time
slice as well.
Ifthe programchangingthetask interruptsthatmodule (i.e.themodule cannotbecompleted
in the available time slice), it is a fatal error, and the control will cut out the output
MACHINE ON; an emergency state is established, followed by an error signal "PLC
TIMEOUT".
Activitiesrequiringabsolutelyfastserviceshavetobeleft tothatmodule, suchasprocessing

2
$" emergency signals,
$" signals of limit-stop positions,
$" signals of ref-point switches.
The module is terminated mandatorily by instruction J1.
1.1.3 Execution of the Module :000
This module is used for serving classical PLC activities where no time dependence exists.
It may be interrupted by the task changer; as soon as its turn is on again, the execution can
beresumed atthepointofinterruption.Theonlyexceptionisthattheprogrammer"givesup"
the remaining time (with instruction J0) in favour of the rest of tasks. Instruction J0 will
cancel (suspend) the PLC task. After 20 ms, on completion of the activities mentioned in
Sections 1.1.2 and 1.1.1, the execution of the program will be resumed on the next turn at
the first instruction following module definition :000.

3
2 Loading, Saving and Editing the PLC Program
The NCT90 controlcan be loaded withthe PLCprogram throughthe serial line or bythe use
of the PLC EDITOR built in the EDIT mode.
2.1 Loading and Saving the PLC Program Through the RS 232C Interface
The PLC program can be loaded and savedthrough the RS 232C interface in the procedures
described in the Operator´s Guide of the control.
The PLC program is a text interpreted in ASCII code; it is stored and delivered in a format
exclusive of spaces, line-feed and carriage-return characters.
2.2 Entry of the PLC Program Through the PLC Editor
The NCT 90 provides a special-purpose editor for editing the PLC program on the control.
Since the control has no ASCII keyboard of its own, the Soft Keys are used for the input of
non-numeric characters and for editing functions. The PLC program will be edited in EDIT
PLC sub-mode.
Entry in EDIT PLC Sub-Mode
Press the EDIT button in SELECT default mode assumed by the control afterEDIT power-on or on depression of the paging button.
Select PLC sub-mode. Since any modification of the PLC program affects thePLC fundamental functions of the machine-tool, the mode will not become active
unless a password is input (to prevent an incidental entry in this mode or
entry by an unauthorized person).
The buttons used in program editing have the following meanings:
Numeric entry buttons.
For a numeric entry, the selected number appears in the place of the cursor
when those buttons are pressed, and the cursor is moved on to the next
position (single-button data input). A new line is commenced automatically
at the end of each line.
STRING Search.
When this button is hit, the title "SEARCH STRING" appears in the bottom line of the
screen, and the cursor is blinking at the point of data entry. The character string can be
entered here, that is to be sought in the program being edited. Of the cursor-moving buttons,
buttons and will produce downward and upward searches across the screen (i.e.
toward higher and lower addresses, respectively). As soon as the STRING has been found,
the cursor will beblinking at the first character of the text found. You can make a correction
here or continue the search.
You can escape from the STRING search mode by pressing the button again.

4
The cursor-moving button.
It will move the cursor rightward, i.e. toward higher addresses; when the button is held
down, the cursor will be moving continuously. At the end of a line it will go automatically
to the first character of the next line. This function remains unchanged in STRING search
mode.
The cursor-moving button.
It will move the cursor leftward, i.e. toward lower addresses; when the button is held down,
the cursor will be moving continuously. At the end of a line it will go automatically to the
first character of the next line. This function remains unchanged in STRING search mode.
-Withthehorizontalpositionleftunchanged,thecursorwillbemovingdownwardacross
the screen (toward higher addresses). It will perform a forward search in STRING search
mode.
- Withthehorizontal positionleftunchange, the cursorwillbemovingupwardacrossthe
screen(towardloweraddresses).ItwillperformabackwardsearchinSTRINGsearchmode.
- Clear button.
It will clear the character in the position of the cursor. In the case of an error signal it can be
used as an overall clear button. When the editing is finished successfully, the message
PASSED will be blinking in the bottomline to signal that the program has passed the check
procedure. Under such conditions the clear button will cause the control to initiate the
automatic re-start of the system software ("PLC compilation").
- INSERT mode.
The cursor is blinking in the area of a full character (otherwise being only an underlining)
to signal that the EDITOR is in insert mode. Under such conditions the new character will
be positioned in front of the one at which the cursor is blinking. Pressing the button again
will return the EDITOR from insert mode to transcript mode.
SOFT KEYS
Paging upward. A screen page will be turned upward across the
PAGE UP screen toward lower addresses.
Pagingdownward.AscreenpagewillbeturneddownwardacrossthePAGE DOWN scree toward higher addresses.
Upward search of module. Moving upward across the screen toward
MODUL UP lower addresses, the editor goes to the previous ":" character and thus
to the previous module.
Downward search of module. Moving downward across the screenMODUL DOWN toward higher addresses, the editor goes to the next ":" character and
thus to the next module.
Movingthecursorleftwardtothefirst characterofthepreviousword.
WORD LEFT
Statistics of the variables used in the PLC program. With the button
STATISTICS

5
pressed, the variables, registers, counters, input-output lines can be
listed on the screen, to which references are made in the program.
Character entrybutton. Although it is the top one of the Soft Keys, it
CHARACT is discussed last because it has by far the most complex function.
When this button is pressed, the Soft Keys will be assigned new
meanings, i.e. the Editor will enter in character input mode.
Program editing
The two last lines of the PLC editor screen are used by the EDITOR with the following
meanings.
Last but one line:
LINE = nn vertical position of the cursor (nn=1 - 9999)
COL = nn horizontal position of the cursor (nn=1 - 64)
PASSED error field or message field
ERRORnn
Last line:
FREE nnnn number of free bytes available for editing the PLC.
Input of characters:
Numeric input the numeric entry buttons are effective in any mode of the PLC
editor.Withanumericentrybuttonpressed,theselectednumberwill
appear immediately in the position of the blinking cursor.
Input of character (non-numeric one):
EnteringinEDITPLC,pressingthetopSoft Keywillenterincharac-
CHARACT ter editing.Undersuchconditions theSoftKeyswillbeassignednew
meanings. Each SOFTKEY field will exhibit maximum 8 characters
(let us refer to them as character groups). Each character can be
enteredbytwoconsecutivebuttons pressed.Firstselectthe particular
group of characters, in which the desired character can be found.
With the character group pressed, each Soft Key will be assigned a
newmeaning.Containedfromlefttorightinthegroup,thecharacters
aredisplayednowinSOFTKEYfieldsbeneath one another. With the
Soft Key containing the desired character pressed, the character
appears in the cursor position, and the cursor is moved on by a
position; the SOFTKEY fields exhibit groups of characters again.
Hitting the paging button will return the default state of the PLC
editor.
In character editing mode the lowermost Soft Key will produce line
CR/LF feed and carriage return. It can also be used for inserting another line
(with the editor used in insert mode).

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2.3 Terminating the Editing of the PLC Program
The PLC editor is used for editing ASCII texts, from which the PLC compiler generates a
machine code that can be executed at a high rate by the central processor unit.
The compilation is commenced automaticallyas soon as you escape from the editor (paging
key). In the course of compilation or on completion of a successful one, the compiler sends
a message to the message field of the screen.
$" If the PLC text contains an error, the compiler returns a blinking "ERROR nn" error
message. When the error message is cleared, the editor checks in again. In the case
of an unsuccessful compilation, the erratic PLC text is displayed on the screen "in
bulk" (without typesetting). The cursor is blinking at the erratic instruction. The
editing keys are effective, so the error can be corrected. The error messages of the
compiler are described in detail in the Appendix.
$" In the case of a flawless PLC text, the compiler returns a blinking message
"ASSEMBLED".Nowthe programmercan carryon the work in oneoftwo different
ways.
$" Pressing button INS (insert). It is one of the data input buttons. Now the EDITOR checks
in again; since, however, the compilation has been successful, the PLC program
appears on the screen in a typeset format. The cursor is blinking at he first ASCII
character.
$" Pressing the ... (clear) button. It is one of the data input buttons. Now the entire NC-PLC
system performs a hot start-up (boodstrapping). The display "PLC compilation"
appears on the screen.
Typesetting the PLC program.
If the compilation is flawless, the PLC compiler will sort the edited ASCII text into 4 logic
categories, typesetting them in 4 separate columns.
1. MODULES (beginning in column 1 of the screen)
2. OPENING/TERMINATION OF CONDITION TEST (beginning in column 9)
3. COMMANDS (beginning in column 17)
4. BRANCHES (beginning in column 25).
The pattern of typesetting is illustrated in the model PLC program.

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3 Modules of the PLC Program
3.1 System Modules
:001 20ms clock module
Called at every 20 ms
Mandatory activities:
$" Handling of alarm signals
$" Handling of limit-stop positions
$" Manipulation of ref-point switches
$" Handling of other signals demanding fast serving
$" Issuing command J1 at the end of the module.
Prohibited instructions:
InstructionWandanyorganizationofprogrampreventingthemodulefrombeingcompleted
in its own time segment ARE STRICTLY FORBIDDEN!
:000 Cyclic PLC module
Called:
$" at the beginning of "life cycle"
$" in the next PLC time segment (if command J0 is issued)
$" under the effect of instruction G000.
Mandatory activities: initialization of the system
Prohibited instructions: none
Recommended program organization in module :000:
:000 C004 ;init module
:100 *
*
*
PLC program
*
*
*
NY405 ;no emergency state
G100 ;cycling
EG000 ;init in emergency state
ZJ0
3.2 Modules of Optional Uses
:002 - :199 except for:
:005 - :019 NC subroutines
:050 - :059 subroutines provided by the manufacturer.