Specifications
Analog Input Modules
31007715 6/2008 143
Data
Word Structure
The first, third, fifth, and seventh registers in the input block of the process image
are the data words. Each register represents the input current of a channel in the
IEC data format. The bit structure in each data register is as follows:
Each data word allows you to represent analog input current data with either signed
integer values ranging from -32 767 to 32 767 or with unsigned integer values in the
range 0 to 65 534.
In the operating range 0 to 20 mA, do not use negative values. If the input data
format is configured for signed integers, the sign bit (bit 15) is always 0.
The value 0 represents 0 mA or 4 mA, depending on the range selected. The value
of either +32 000 (signed) or 64 000 (unsigned) represents 20 mA. Errors and
warnings are reported in both operating ranges at the following counts:
Type of Error
or Warning
4 to 20 mA Range (default) 0 to 20 mA Range
Current Signed
Count
Unsigned
Count
Current Signed
Count
Unsigned
Count
OCE 20.38 mA 32 767 65 534 20.48 mA 32 767 65 534
OCW > 20 mA 32 001 64 001 > 20 mA 32 001 64 001
UCE < 3.62 mA (767 N/A 0 0 0
UCW < 4 mA -1 N/A < 0.48 mA 767 1535
BWE < 1 mA N/A N/A N/A
2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
sign
8
0
Signed Input Data Register Format
12
3
4
5
6
7
910111213
1415
2
2
2
1
2
0
2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
8
0
Unsigned Input Data Register Format
12
3
4
5
6
7
910111213
14
15
2
2
2
1
2
0
2
15
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