Siemens SINUMERIK 840C - Manual (Page 273)

6 NC Machine Data (NC MD), NC Setting Data (NC SD) 12.93
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: In the next block
Example:
N1 G0 G90 X80 Y55 F500 LF
N2 G02 X50 Y85 I50 J55 F500 LF
N3 G01 X50 Y75 LF
N4 G03 X50 Y35 I50 J55 LF
N5 M30 LF
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.
G03
N4
N2
G02
Y
85
75
55
35
50 80 X
N3
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 G91 I.. J = 0 need not be programmed. G91 refers to
both I and to the non-programmed J.
G02 X50 Y60 G90 I.. J = 0 need not be programmed. In this case, G90
lies in the workpiece centre point. Circle end
position error is displayed (alarm 2048).
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SINUMERIK 840C (IA)