VTI Instruments EX1000A, User Manual

Page: 58 / 320

VTI Instruments Corp.
58 EX10xxA Triggering
NOTE In a mixed thermocouple system, it is very easy to accidentally mismatch the hardware setup and
the software configuration setup. Care is especially warranted, as the resultant errors may not be
large enough to obviously indicate a problem, but be significantly larger than the accuracy
specification of the instrument.
Linear Correction
The EX10xxA provides the capability to apply a linear transformation on all measurement data after
EU conversion. Each channel can be programmed with a gain and offset which are applied as
gain*(data-offset).
Gains default to 1.0 and offsets default to 0.0.
V
OLTAGE
M
EASUREMENT
R
ANGES
The EX10xxA provides ±0.067 V and ±0.1 V voltage measurement ranges on thermocouple
channels and voltage channels additionally provide ranges of ±0.01 V, ±1 V, and ±10 V. Voltage
measurement range is programmable on a per-channel basis.
EX10xxA-51C has only option for voltage channels in the following range ±0.01 V, ±1 V, and
±10 V. Voltage measurement range is programmable on a per-channel basis.
The default selection for voltage channels is the ±10 V range, while thermocouple channels default
to a range of ±67 mV.
H
ARDWARE
F
ILTER
Each EX10xxA input channel can be individually configured with a hardware filter of 4 Hz, 15 Hz,
40 Hz, 100 Hz, 500 Hz, and 1 kHz cutoff frequency. Of the five settings, the 4 Hz setting is suitable
for the majority of temperature measurement applications. It offers sufficient response to pass
medium gauge thermocouple signals without distortion, while providing the highest degree of
(50/60) Hz common mode rejection. This setting also provides the lowest noise floor and is
recommended for all applications that do not require a higher bandwidth. For those that do, however,
the additional filter setting provides that capability. Their response will pass the output from even
the fastest fine-gauge thermocouples with little distortion.
The default selection is 4 Hz.
M
EASUREMENT
R
ANGE
/ I
NPUT
P
ROTECTION
The specified input voltage range of the EX10xxA thermocouple channels is ±67 mV or ±100 mV
for voltage measurements. This level refers to the maximum differential voltage, or voltage that is
applied between the (+) and (–) input terminals, that can be measured without distortion. The
maximum common mode voltage, or voltage that is applied to the (+) and (–) inputs together, that
can be applied without causing out-of-specification distortion of the differential measurement is
±10 V. Application of voltage beyond these levels will result in incorrect measurements, but no
instrument damage, up to a maximum of ±35 V.
NOTE The application of voltages beyond ±35 V can permanently damage the EX10xxA.