Specifications
Analog Input Modules
94
31007715 6/2008
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 -767 to 32 767 or with unsigned integer values in the
range 0to65535.
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
14
15
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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