VTI Instruments EX1000A, User Manual

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VTI Instruments Corp.
18 EX10xxA Introduction
In terms of voltage, the thermocouple connectors may only accept an input voltage of ±67 mV when
performing temperature conversion. When in voltage mode, these connectors can accept either
±0.067 V or ±0.1 V inputs. The voltage connectors may use either ±0.01 V, ±0.067 V, ±0.1 V,
±1.0 V, or ±10.0 V inputs for both EU temperature conversion or voltage measurements. When
temperature is selected, the instrument automatically switches the selected channel(s) to the ±67 mV
range. The EX1000A-TC is a special case where thermocouple inputs are used for voltage
measurement and may utilize all input ranges available to the voltage connectors. Table 1- provides
an overview of each models capabilities.
For maximum flexibility, each channel can be independently configured with regards to its
thermocouple conversion. Moreover, non-standard thermocouples are accommodated through the
input of user-defined thermocouple polynomial coefficients.
Hardware Filter
Each EX10xxA input channel can be individually configured with one of six low-pass hardware
filters. Five of these filters are 2-pole Bessel filters with frequencies of 4 Hz, 15 Hz, 40 Hz, 100 Hz
and 500 Hz. The sixth filter is a single-pole Butterworth filter with a frequency of 1 kHz, providing
a simple anti-alias filter when the 1 kSa/s range is used. These filters allow the EX10xxA to cover
a diverse range of applications, even within the same unit. Suitable for most applications, the 4 Hz
setting provides the lowest noise floor and exceptional common mode rejection. For higher speed
applications, the 1 kHz filter will pass the output from even the fastest fine-gauge thermocouples
with little distortion.
Input Connectors
The EX1016A, EX1032A, and EX1048A employ uncompensated (Cu-Cu) mini-thermocouple
female jacks as an input connector. This connector provides a solid, reliable connection that is also
easily changeable. Since it is not thermocouple-type specific, different thermocouple types can be
mixed throughout the unit without hardware modification. The EX1000A, EX1016A and EX1032A
also employ a standard 50-pin D-sub connector for the voltage input channels. All the RX10xx
channels are individually routed via the screw terminals which is placed just below the instrument
top cover and the cable bunch is brought out through the cable gland.
Sampling Rate
The EX10xxA can be configured for a sampling rate up to a maximum of 1 kSa/s, regardless of the
number of channels included in the scan list. When the requested sampling rate is significantly less
than 1 kSa/s, however, the EX10xxA automatically takes and averages multiple samples. This offers
improved noise performance, while maintaining the requested data output rate.
Digital I/O and Limits
The EX10xxA provides two unique sets of programmable limits that are used for open transducer
detection as well as general purpose input channel monitoring. These limits are programmable on a
per channel basis and are evaluated with each completed scan. The output of limit evaluations is
presented in three forms. The operation of the front panel LEDs is tied to the upper and lower limit
values of one limit set. The operation of the digital I/O port can be optionally linked to any
combination of the upper and lower limit values of either or both limit sets. Finally, the limit
condition information is accessible through the instrument driver.
The EX10xxA features an 8-channel digital I/O port on the rear panel of the instrument, except
RX10xx which has 2-channel digital I/O routed through the 13 pin circular connector (P1). This
port can be used as an arm/trigger source, for presentation of limit evaluation information, and as a
general purpose output device. As a general purpose output device, each DIO channel can be
independently programmed with regards to its output functionality and its static level to assume
when enabled as an output. For expanded and more automated operation, each DIO channel can be
independently linked to one or multiple limit conditions on one or more input channels.