Basler A400K, User Manual

Page: 113 / 176

Configuring the Camera
Basler A400k 4-13
DRAFT
4.2.2 Feature Control and Status Registers
The feature control and status registers (CSRs) let you set the parameters for camera features
such as exposure mode, gain, offset, and the AOI. These registers also let you check the current
parameter settings and the status for each feature.
Each feature has one or more CSRs associated with it. The fields within a feature’s CSR(s) are
used to control how the feature operates. By using a binary write command to write to fields within
a feature’s CSR(s) you can change the parameter settings for the feature. By using binary read
commands, you can determine the current setting for the parameters and get information about
the feature’s status.
The address for any field within a register is equal to the register base address plus the offset for
the field. Look at the Video Data Output Mode CSR on page
4-15 as an example. The Mode field
of this register has an address of 0x1701 (the base address of 0x1700 plus the offset of 0x0001).
By writing a value to this address, you can select the video data output mode. By reading the value
at this address, you can determine the current output mode setting.
The Video Data Output Mode CSR is a simple CSR with only two fields. Most of the other feature
CSRs have several read/write fields that let you set the parameters associated with the feature.
They may also have read only fields that contain information about the minimum and maximum
allowed setting for each parameter. Section
4.2.2.2 lists the feature CSRs in A400k cameras and
shows detailed information about the use of each field within the register.
4.2.2.1 “Raw” Value Fields vs. “Absolute” Value Fields
As you look through the descriptions of the feature CSRs, you will notice that some CSRs have a
parameter that can be set by writing a value to a “raw” field or by writing a value to an “absolute”
field. You will find this to be true for the Exposure Time, Frame Period, Gain and Offset
parameters. The common characteristic among these parameters is that they are expressed as
rational numbers. These numbers are on a continuous scale rather than on a scale of discrete
integers. Any one of the parameters expressed as rational numbers can be set on a “raw” scale
or on an “absolute” scale. A raw scale is simply a range of integer values that has no defined units.
An absolute scale is a range of floating point values that has defined units.
Let’s look at the Exposure Time parameter as an example:
Setting the Raw Exposure Time
If you adjust the exposure time by writing a value to the Raw Exposure Time field of the Exposure
Time CSR, you can write any integer value from 1 to 4192982 (decimal). Writing an integer value
to the exposure time register sets the exposure time, but it doesn’t directly tell you how many
microseconds of exposure time you will be getting from the camera at that setting. To determine
the microseconds of exposure time you are getting at a particular raw exposure time setting, you
must use the formula: microseconds = raw setting x 4.56 µs
.
For example, if the Raw Exposure
Time field is set to 3 (decimal):
microseconds = raw setting x 4.56 µs
microseconds = 3 x 4.56 µs
microseconds = 13.68
So with the Raw Exposure Time field set to 3, the camera would be set for 13.68 µs of exposure.