User manual

Chapter 1 Series 1700 Introduction
1-8 ADVANCED MICRO CONTROLS INC
Transducer Setup Parameters (continued)
Circular Offset
The Circular Offset lets you change the position count without rotating the transducer shaft.
This offset is most commonly used to force the position to the correct count after the machine
has been mechanically aligned.
hýThe Circular Offset default value is zero.
hýThe Circular Offset can be programmed from zero to (Scale Factor -1).
hýProgramming the Scale Factor resets the Circular Offset to zero.
The Preset Value parameter is directly related to the Circular Offset. Presetting
the position count to the Preset Value is accomplished by recalculating the
Circular Offset. For more information on the Preset Value parameter, see its
section below.
Linear Offset
The Linear Offset changes the range of position counts by adding a fixed number to it. The
Linear Offsets use is best illustrated with an example.
A 1741 is used to measure a 5.000 meter span with one milli-
meter resolution. Therefore, the total number of counts over the
full travel is:
5.000 meters * 1000 mm/meter = 5000 counts.
The Scale Factor parameter is then set to this value. The 5.000
meters that the transducer measures is in the range of 2.500 to
7.500 meters on the machine. You can use the Linear Offset to
force the module to send the position data to the processor in the
correct format instead of using the processor to add an offset once
the position value is in the data table. The formula for the Linear
Offset is:
Minimum Desired Value * Resolution = Linear Offset
2.500 meters * 1000 mm/meter = 2500 counts
hýThe Linear Offset default value is zero.
hýThe Linear Offset can be programmed from zero to (9,999 - (Scale Factor -1)).
hýProgramming the Scale Factor resets the Linear Offset to zero.
Preset Value
The Preset Value parameter allows you to set the value of position count without calculating
the required offset. Programming the Preset Value does not change the position data, it only
sets the value that the position will change to when a Preset Command is initiated. The
position can be preset from the keyboard or with a backplane command.
hýThe Preset Value defaults to zero.
hýThe Preset Value can be programmed from zero to (Scale Factor - 1).
hýProgramming the Scale Factor resets the Preset Value to zero.
hýIf the Linear Offset value is not equal to zero, the new position value will be (Linear
Offset + Preset Value) after it is preset.
0 m
.581 in
Linear
Offset
2.5 m
7.5 m
1.162 in
5 m
Span
Figure 1.4
Linear Offset
Example