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B.3 Analog Output Formats
You can configure ADAM analog output modules to receive data from
the host in one of the following data formats:
-Engineering Units
-Percent of FSR
-Twos complement hexadecimal
Data for ADAM modules can be used in any one of the following data
formats:
B.3.1 Engineering Units
This format is chosen by setting bits 0 and 1 of the data format/slew
rate/checksum parameter to 00.
Data are presented in natural units such as milliamps. When the value
in engineering format is converted to computer language, it is presented
in six characters. These characters are ordered as two decimal digits, a
decimal point, and then three decimal digits. As a result, the resolution
is 5 μA.
For example, an analog output module (address 01h) is configured for a
0 to 20 mA range. If the output value is + 4.762 mA, the format of the
Analog Data Out command would be #0104.762(cr).
B.3.2 Percent of Span
The Percent of Span format is employed by setting bits 0 and 1 of the
data format/slew rate/checksum parameter to 01.
This format consists of a "+" or "-" sign, three decimal digits, a decimal
point and two decimal digits. Data are presented as the value sent by the
output signal relative to the span of the output (percent of span).
The maximum resolution is 0.2% of the span (5 μA for the 0 to 20 mA
output range); therefore, the desired output value is 10 mA. The format
of the Analog Data Out command is as follows:
#01+050.00 (cr). It indicates that the output is at 50% of the span, and
the decimal point is fixed.
B.3.3 Hexadecimal
This format is selected by setting bits 0 and 1 of the data format/slew
rate/checksum parameter to 10.
ASCII's condensed hexadecimal representation of data provides high
resolution. The format consists of a 3-character hexadecimal string
representing a 12-bit binary value. The resolution for the 0 to 20mA
output range equals to .025% of the span, which is also equivalent to
5μA. The corresponding value for 000 is 0mA; likewise, the value FFF
corresponds to 20mA.
Appendix B Data Formats and I/O Ranges B-11
Appendix B
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