Siemens SINUMERIK 828D Function Manual page 717

Run-up
After run-up (POWER ON) the last used offset values for the "Zero offset external" are stored and do not become
effective again until there is a renewed activation signal.
System frames are retained during Power ON, depending on the following machine data:
MD24008 $MC_CHSFRAME_POWERON_MASK (reset system frames after Power On)
RESET/end of program
The activated values remain active after RESET and program end.
Reset response of channel-specific system fames as follows:
The system frame for the "external zero offset" is active after RESET with the following machine data setting:
MD24006 $MC_CHSFRAME_RESET_MASK, Bit 1 = 1
The "external zero offset" in the active system frame is deleted in the data management through the following
machine data setting:
MD24006 $MC_CHSFRAME_RESET_MASK, Bit 1 = 0
The following frames are active after RESET:
• System frame for:
MD24006 $MC_CHSFRAME_RESET_MASK, Bit 4 = 1 (workpiece reference point)
MD24006 $MC_CHSFRAME_RESET_MASK, Bit 5 = 1 (cycles)
Suppression
The NC program instruction SUPA suppresses the "Zero offset external" while the block is being processed.
The command G74 (reference point approach) and the equivalent operator actions in "Reference point approach"
mode suppress the "Zero offset external" for the duration of the reference point approach.
With G74, i.e., "Automatic" or "MDA" mode, the previously active "Zero offset external" automatically becomes
active again with the next traverse motion in the block.
After a mode change from "Reference point approach" mode, the VDI signal for the referenced axes must be set
for reactivation.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
K2: Axis Types, Coordinate Systems, Frames
10.4 Coordinate systems
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