Table of Contents
24/7 Data Acquisition Wildcard Users Guide
To start using the 24/7 Data Acquisition Wildcard, follow these simple steps:
Once the hardware and software are properly configured, you can obtain high-resolution samples with the pre-coded high level driver routines.
The 24/7 Data Acquisition Wildcard consists of:
The 24/7 Data Acquisition Wildcard has an on-board 2.5 V voltage reference that is accurate to +/- 0.005 V. This reference is available for use by sensors requiring a reference or producing a proportionate output. It can supply up to 10 ma. The reference voltage is available on pins 7 (REF+) and 13 (REF-) on H2 of the 24/7 Data Acquisition Wildcard. To use the on-board reference voltage for analog to digital conversions call Use_Onboard_Ref. You can also use your own external reference voltage by connecting an external voltage to pins 9 (FDREF+) and 11 (FDREF-) of H2 and calling Use_External_Ref. Be sure that FDREF+ is always greater than FDREF- for correct operation of the analog to digital converter. The recommended reference voltage for the analog to digital converter is 2.5 V. The 24/7 Data Acquisition Wildcard is functional with external reference voltages from 2.5 volts down to 1 volt but with degraded performance as the output noise will, in terms of LSB size, be larger. If jumper J1 is installed, the reference voltage that appears on the REF+ output pin is changed to 3.0 V, which exceeds the specified reference input voltage by 0.5 volt. DO NOT USE THIS 3.0 VOLTS AS A REFERENCE VOLTAGE! That is, if jumper J1 is installed do not call Use_Onboard_Ref or connect REF+ and REF- to FDREF+ and FDREF-. The 3.0 V option is useful for powering external sensors and transducers and provides up to 10 mA of current.
Figure 1 shows a typical application of 3.0 V option with an RTD.
Fig.1: Typical Application of the 3.0V Option
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