Data Acquisition And Instrument Control - MicroCal VP-ITC User Manual

Section 1: VP-ITC System Introduction

1.2 Data Acquisition and Instrument Control

The VP-ITC is operated by two computer interface boards and a serial interface that reside inside
the Computer Controller. The boards are pre-configured and calibrated at MicroCal, and need no
adjustments by the user.
Data acquisition is accomplished through a 16-bit A/D (analog to digital) converter board. There
are five differential inputs to the A/D, consisting of the DP or differential power between the
reference and sample cells, the Jacket Temperature, the DeltaT (temperature difference between
the cells and the adiabatic jacket), Shield Temperature (the outer shield temperature), and the
ATP channel (heat sink information). The default A/D inputs range from –1.25 volts to +1.25
volts for all input channels but can be changed through VPViewer. Additional available input
ranges are +/- 2.5 and +/- 5 volts.
ITC instrument control is accomplished through the second interface board, a 16 bit D/A (digital
to analog) converter board. Programmed by the VPViewer software, this board will regulate the
temperature of the VP-ITC, equilibrate the ITC in preparation for a titration run, and carry out the
ITC experiment.
The VP ITC injection system mounts on top of the cell unit and is controlled by VPViewer
through a standard RS-232 serial interface in the Computer Controller
Although other Windows' programs can be used while the VP-ITC is running without affecting
the data acquisition or calorimeter control, it should be realized that there are real time operations
taking place during an experiment, and that performing CPU intensive tasks while an experiment
is in progress can 'glitch' the ITC baseline. Users are encouraged to avoid large file copying to
disk drives, large print jobs and recursive control loops while the VP-ITC is in the midst of an
injection run. Users can carry out routine data analysis while the VP-ITC is running.
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