User Manual V 1-4.XX User guide

7-4 Setting Up the Input/Output
As Figures 7.1 and 7.2 show, each analog input and output parameter
has associated offset and scale parameters. The 1336 IMPACT drive
provides the offset and scale parameters so that you can adjust the
range of the analog input and output sources and use the entire
internal range of drive units.
The following table provides information about the analog scale and
offset parameters.
Determining the Offset and Scale Values for an Analog
Input
To determine the offset and scale values for an analog input, you need
to know the following:
• the range of units coming from the analog input (for example,
-5V to +5V or 0V to 10V)
• the range that you want to see in internal drive units (for example,
-2048 to +2048 or 0 to 4096)
You determine the value of the offset parameter by comparing the
range of units coming from the analog input to the range that you
want to see in internal drive units. For example, if you need to get a
± drive unit range from a 0 to 10V input range, you can use an offset
of -5 (subtracting 5 from both 0 and 10 gives you a -5 to +5 range).
Once you have the proper range, the offset is converted to an internal,
or digital, value. 10V is always equal to 2048 internal drive units. 5V
equals 1024 internal drive units. For this example, the internal drive
units are ±1024.
If you are having problems determining your scale and offset values
or are using a PLC, refer to the explanation in the application
section.
Input Range Output Range Affects Description
Offset parameters (97,
100, 103, 106, 109, and
112)
±20 ±20
analog value
(external units)
Lets you shift the input range. For example,
if your analog input values have a range of 0
to 10V, you can use an offset value of -5 to
change the range to ±5V.
Scale parameters (98,
101, 104, 107, 110, and
113)
±16 ±1
digital value
(internal units)
Lets you use the full range of internal drive
units. The maximum range is ±32767
internal units. The maximum analog to
digital value is ±2048.
Filter parameters (182,
183, and 184)
0 – 200 NA
digital value
(internal units)
Lets you use a low pass filter to reduce the
noise received from the input.
Not all applications require both an offset parameter and a scale
parameter. For example, if you have an input range of 0 to 10V and
you want a range of 0 to 8192 internal drive units, you do not need to
supply an offset value. If you do not require an offset value, make
sure that the offset parameter is set to 0. Likewise, you may not need
a scale value. If this is the case, make sure that the scale parameter
is set to 1.
file:
Interface/Comm
group:
Analog Inputs