Campbell Scientific CR9000X Measurement and Control System - Manual (Page 111)

Section 3. CR9000X Measurement Details
for the given Sinc filter and scan interval. The integration and Sinc filter
order that a given CR9058E is using can be seen through RTDaq's
terminal mode window (DataLogger/Terminal Emulator) or any other
terminal emulator. Click on "Open Terminal" and next hit Enter several
times until the CR9000> prompt is returned. Type in "4" and enter. The
CR9058Es' slot numbers, integration times, and Sinc filters will be
returned.
In most applications, when manually selecting the Sinc filter
order, we recommend using the Fifth Order (-5) in order to
minimize signal attenuation at lower frequencies, and to
improve the filtering of higher order frequencies (See Section
3.2.3 "Hard Setting the Filter Order"). One exception to this is
for applications requiring a notch filter: it will be necessary to
set the integration time corresponding to the frequency that is
desired to be filtered. NOTE
• A CR9058E can only have one integration time per scan interval that
applies to all ten of its channels. If multiple measurement instructions
within a scan are tied to a single CR9058E module, and they don’t all have
the same Integ time parameter, then a compile error will occur.
• The Integ parameter in the VoltDiff and TCDiff instructions, within the
constraints listed above, can be used to adjust the measurement frequency
response. For example, for both 60 Hz and 50 Hz rejection the Integ
parameter could be set = 300,000 microseconds.
• Input reversal (for offset cancellation) isn’t individually selectable
within the ten channels of a CR9058E module. If any one channel of a
CR9058E’s ten input channels has input reversal selected, by setting
the Rev parameter of the VoltDiff or TCDiff instruction to true, input
reversal will be applied to all ten channels. If other VoltDiff or
TCDiff instructions tied to this module within the same scan don’t
have the Rev parameter set True, then a compile error will occur.
• The CR9058E ModuleTemp measurement is independent of the isolated
input measurements. The CR9058E ModuleTemp measurement method is
identical to that of the CR9051E, using a platinum resistance thermometer
to obtain the thermocouple reference junction temperature at the EZ-
connect terminal module.
• Because heat is generated within the CR9058E, a thermal gradient can
develop across the EZ-connect terminal block which can produce errors in
thermocouple measurements. To minimize this error, keep the CR9058EC
covers in place. Also, type E or K thermocouples are better than type T
because type T thermocouples have a copper conductor which is an
excellent conductor of heat increasing the thermal gradient across the
terminal block.
• Each channel has an H (high) input terminal, a L (low) terminal, and a G
(isolated ground) terminal. The isolated ground terminals are not
connected to the CR9000X system ground. The isolated ground terminal
can be used to connect the shield of a shielded cable. Also, when un-
shielded thermocouples are used, the G terminal can be tied to the H or L
terminal to reduce noise in the readings.
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