Datalogic AMT58 Series, Manual

Page: 238 / 435

CYCLIC DATA EXCHANGE - STD SIGNALS
58
AMT58...PN
Request set/shift of home position
Bit 12
The preset function is controlled by bits 11 and 12 in this Sensor 1 control word G1_STW
and acknowledged by the bit 12 Set/shift of home position executed in the sensor status
word G1_ZSW. The preset value is 0 by default and can be set by using the Telegram 860
and G1_XIST1_PRESET_VALUE (see "
G1_XIST1_PRESET_VALUE" on page 54
). The preset
function has an absolute and a relative operating mode selectable by means of the bit
11 Home position mode in this Sensor 1 control word G1_STW (0 = absolute; 1 = rela -
tive). Bit 11 and bit 12 in the Sensor 1 control word G1_STW control the preset function
as described in the table below.
The Preset command automatically saves the calculated internal offset values.
BIT 12 BIT 11 ACTION
0 X
Normal operating mode.
The encoder will make no change in the output value.
1 0
Preset mode absolute
The encoder reads the current position value and calculates an
internal offset value from the preset value G1_XIST1_PRE -
SET_VALUE and the read position value. The position value is then
shifted with the calculated offset value to get the current position
value equal to the preset value. The encoder acknowledges the pre -
set by setting the bit 12 Set/shift of home position executed in the
sensor status word G1_ZSW. Now the bit 12 Request set/shift of
home position in the sensor 1 control word G1_STW can be set to
zero by the Master. The encoder will end the preset cycle by clearing
the bit 12 Set/shift of home position executed in the sensor status
word G1_ZSW. The new internal offset value is securely stored in
case of voltage breakdown and uploaded again at each power on.
1 1
Preset mode relative (offset)
The encoder uses the preset value G1_XIST1_PRESET_VALUE as a
relative offset value. In this mode the current position value is
shifted by the value deriving from the preset value.
EXAMPLE
A preset value "1000" is intended to shift the current position value
by 1000 steps in the positive counting direction. So a "real" position
value of "5000" will have the value "6000" after the relative shifting
sequence. The encoder will set the bit 12 Set/shift of home position
executed in the sensor status word G1_ZSW to acknowledge the
execution of the shifting. The bit 12 Request set/shift of home posi -
tion in the sensor control word G1_STW can now be set to zero by
the Master. The encoder will end the preset cycle by clearing the bit
12 Set/shift of home position executed in the sensor status word
G1_ZSW. The internal offset value will be shifted according to the
transferred preset value. The new offset value is securely stored in
case of voltage breakdown and uploaded again at each power on.
NOTE
Refer to "
G1_XIST1 Preset control" on page 64
and "
Preset diagram" on
page 86