Siemens SINUMERIK 808D Service Manual page 16

Service case
of hardware
fault
Hardware limit
switch fault
Fault description:
1. Hardware limit switch alarm appears on the PPU.
2. The machine has crossed the hardware limit switch, but can still move, no
alarm.
Diagnostic steps
If the fault is: Hardware
Case1
limit switch alarm appears
on the PPU.
Press the "Reset" button on the PPU and press the direction key controlling
the feed shaft movement on the PPU at the same time to make the
feed axis move in the opposite direction and break away from the hardware
limit switch. The alarm can then be cleared.
The hardware limit switches on the machine must be checked if these
methods do not resolve the fault.
1. Use a multi-meter to check whether the hardware limit switch connection is good.
2. Check whether the hardware limit switches are damaged.
If the fault is ： The machine has crossed the hardware limit
Case2
switch, but can still move, no alarm.
Check whether the hardware limit switch connection is short-circuited
with the high level.
Check whether the hardware limit switches are damaged.
Service guide
Startup cannot
return to the
reference point
Fault description:
1. Press the axis + (or axis-) key, the screen coordinates do not change and
the machine does not move.
2. Press the axis + (or axis-) key, screen coordinates change but the machine
does not move.
3. Press the axis + (or axis-) key, the machine can move until the hardware
limit switch alarm appears.
4. Press the axis + (or axis-) key, the machine is always moving in the opposite
direction.
5. Press the axis + (or axis-) key, the machine moves only a short distance.
6. Press the axis + (or axis-) key, the machine alarm 20002 appears after exiting
the slowdown switch.
7. Press the axis + (or axis-) key, the start point and automatic processing
program are running normally, but the system does not respond when returning
to the reference point.
Diagnostic steps
If the fault is ： Press the axis + (or axis-) key, the screen coordinates
Case1
do not change and the machine does not move.
Check if there is an alarm number on the PPU screen, continue operation
after eliminating the alarm via the " Reset " key.
The machine data is lost if the alarm numbers 004060/004062/004065
appear; in this case, it is necessary to back up the data and restart after
power-off to check whether the fault has been eliminated.
page 16 808D turning and milling