Advantech Adam - 4021, User Manual, Page: 242 / 286

ADAM-4000 Series User Manual 230
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 com -
mand 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.
Note! * Resolution is one LSB of 16 bits