Chapter 3
Chapter 3 I/O Modules
3-5
Function Description for the ADAM-4011 Thermocouple Input
Module
To provide a better understanding of the ADAM module functions,
the following is a description of the module ADAM-4011 with the most
extensive set of functions.
All analog input data first flow through the PGA (programmable
gain amplifier). The amplifier can vary its gain from 1 to 128. The PGA
then automatically adjusts the signal to a range from -2.5 V to +2.5 V.
This ensures an optimal input voltage and resolution for the A/D
converter.
The A/D conversion is supervised by the microprocessor that holds
the calibration software. Two kinds of calibrations, Auto Zero and Auto
Span calibrations, take place automatically in startup or reset. Normal
calibration is used to adjust the signal according to calibration
parameters defined by the user.
The digital 10 Hz filter provides a steady state output by using the
Δ function.
Before the data enter the microprocessor, they pass through an
optical isolation device which prevents the chance of circuit damaging
caused by power surges from the ground terminal.
The microprocessor has six basic functions:
- Linearization of T/C (Thermocouple)
- Communication software and command set
- Calibration software
- Alarm monitoring
- Event counting
- Management of the EEPROM device that holds the system parameters
- Data transformation
After data have been transformed to the right data format, they are
being passed on to the RS-485 output port.
If an input value exceeds the High alarm setting or falls below the
Low alarm setting, a flag is set in one of the Digital Output channels.
Finally, the on-board switching regulator accepts voltage between +10
and +30 VDC, and it has an isolation value of 500 VDC to protect your
equipment from damages caused by power surges.