Appendix B
Appendix B Data Formats and I/O Ranges B-5
When in the FSR mode, if a value exceeds the uppermost value of the input
range, an overrange feature is automatically invoked by the ADAM analog
input modules. Take, for instance, an analog module which is configured for
a ±5 V range but one of the values read is + 5.5V. The resulting value would
then be 110%.
The readings must fall within the input range to be guaranteed of accuracy.
Although they are typically linear readings which fall between the ±100%
and ±115% limits are not accurate, but still generally linear. Readings
beyond these limits are neither accurate nor linear.
B.1.3 Twos complement hexadecimal
Easily transferred to integer format the Twos Complement Hexadecimal
format represents the data in ASCII hexadecimal form providing rapid
communication, high resolution and easy conversion to computer-compati-
ble integer format.
To indicate twos complement hexadecimal bits 0 and 1 of the data format/
checksum/integration time parameter must be set to 10. This format displays
data in the form of a 4-character hexadecimal string. This string represents a
16-bit twos complement binary value. Positive full scale is denoted as 7FFF
(+32,767) while negative full scale is represented by the value 8000 (-32,768).
The resolution is one least significant bit (LSB) of 16 bits.
Example
The input value is -1.234 V. An analog input module is configured for a
±5 V range. The value returned is:
E069 (cr)
This value is equivalent to the signed integer -8087.
Input ranges with voltage and milliamp values are used with the full
calibrated voltage range from 8000 to 7FFF. For instance, an ADAM-4011
module is given a ±5 V input range. In this case -5 V is represented as 8000h
and +5 V is denoted as 7FFFh.
When thermocouple input ranges are used, an input range which is bipolar
To Next Page
Loading...
Need help?
General
