Siemens SINUMERIK 840C Installation Instructions Manual page 273

6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.6.1 General MD bits (general bits)
Bit 5 When bit 5 is set, the interpolation parameters (I, J, K) can be programmed either as
absolutes (G90) or as increments (G91) in the block (also see NC MD 5007,
bit 5). The interpolation parameters for contour definitions (blueprint programming)
must always be specified incrementally (G91), regardless of whether bit 5 is set or not.
Active:
Example:
N1 G0 G90 X80
N2 G02 X50 Y85
N3 G01 X50 Y75
N4 G03 X50 Y35
L F
N5 M30
When the interpolation parameters are specified as absolutes, the centre point of
the circle refers to the centre point of the workpiece and not the starting point of the
circular path of the circle.
85
75
55
35
If an interpolation parameter was not programmed because it was "0", the G
function, which also precedes the programmed interpolation parameter, also refers
to the interpolation parameter that was not programmed.
Example:
G02 X50 Y60
G02 X50 Y60
6–88
In the next block
L F
Y55 F500
L F
I50 J55 F500
L F
L F
I50 J55
Y
G03
N4
N2
50
J = 0 need not be programmed. G91 refers to
G91 I..
both I and to the non-programmed J.
J = 0 need not be programmed. In this case, G90
G90 I..
lies in the workpiece centre point. Circle end
position error is displayed (alarm 2048).
©
Siemens AG 1992 All Rights Reserved
N3
G02
80 X
6FC5197- AA50
SINUMERIK 840C (IA)
12.93