X20 system modules • Analog input modules • X20AI2438
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X20 system User's Manual 3.10
4.3.7.9.7 Analog signal - Configuration
How the analog signal is displayed can be adapted to the requirements of the application. Separate configuration
registers per channel are available to aid in this.
4.3.7.9.7.1 Analog mode
Names (pChannelName):
AnMode_1
AnMode_2
These registers are used to predefine the operating parameters that the module will be using for the respective
channel. Each channel must be enabled individually and can be configured and operated independently.
It is extremely important to not that different limit values need to be configured for any display normalizing that
needs to take place.
Data type
Values
UINT
See bit structure
Bit structure:
Bit
Name
Information
0
Channel 0x turned off
0
Channel
1
Channel 0x enabled (bus controller default setting)
0
Open line monitoring turned off
1
Open line detection
1
Open line monitoring enabled (bus controller default setting)
0
Underflow detection turned off
2
Underflow detection
1
Underflow detection enabled (bus controller default setting)
0
Use replacement values when an error occurs (bus controller
default setting)
3
Replacement value strategy
1
Keep the last valid converted value
00
Displays 0...25 mA as 0...32767
01
Displays 0...25 mA as 0...25000 [µA] (bus controller default set-
ting)
10
Displays 4...20 mA as 0...32767
4-5
Normalization
11
Displays 0...25 mA as 0...65535
6-15
Reserved
4.3.7.9.7.2 Sample rate
Names (pChannelName):
Samplerate_1
Samplerate_2
A sample rate can be configured for both analog inputs independently of one another. The following formula for
this parameter is derived using the desired sampling frequency:
Sample rate for ADC = (4920000/1024)/sampling frequency
Data type
Values
UINT
48 - 1023: Sample rate
960 ... 200 ms
... 5 Hz
480 ... 100 ms
... 10 Hz
320 ... 66.7 ms
... 15 Hz
192 ... 40 ms
... 25 Hz
160 ... 33.3 ms
... 30 Hz
96
... 20 ms
... 50 Hz (bus controller default setting)
80
... 16.7 ms
... 60 Hz
48
... 10 ms
... 100 Hz
The fastest sample rate of 10 ms for the analog inputs is predefined by the cut-off frequency of the hardware filter.
When using HART communication, however, a sample rate not faster than 100 ms is recommended.
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