Campbell CR9000, Instruction Manual

Page: 63 / 218

Section 3. CR9000 Measurement Details
3-19
•
The Integ parameter in VoltDiff and in TCDiff (not in ModuleTemp) can
be set to –1, -2, -3, -4, or -5 and the CR9058E will set the corresponding
synch filter of 1, 2, 3, 4, or 5. The integration time will be maximized for
the given synch filter and scan interval. The integration and synch filter
order that a given CR9058E is using can be seen through PC9000's
terminal mode window (Tools/Diagnostics/Terminal Mode). In the I/O
Port area, click on "Open Port". Next, click in the Low Level I/O section
and hit Enter several times until the CR9000> prompt is returned. Type in
"4" and enter. The CR9058Es' slot numbers, integration times, and sync
filters will be returned.
•
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, without generating an error,
input reversal will be applied to them all anyway.
•
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 the Integration time for all of that
module's channels will be set by the value of the Integ time parameter of
the last measurement instruction, tied to that module, within the scan.
•
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 = 100,000 microseconds.
•
The CR9058E ModuleTemp measurement is independent of the isolated
input measurements. The CR9058E ModuleTemp measurement method is
identical to that of the CR9050, 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.