Campbell Scientific CR10X Measurement and Control System - Manual (Page 143)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-11
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Control port
02: 4 Input location of pulse
length in hundredths of
a second
Input location altered: 0
Input locations read: 1
*** 22 EXCITATION WITH DELAY ***
FUNCTION
This instruction is used in conjunction with
others for measuring a response to a timed
excitation using the switched analog outputs. It
sets the selected excitation output to a specific
value, waits for the specified time, then turns off
the excitation and waits an additional specified
time before continuing execution of the following
instruction. Analog power is turned off during
delay after excitation to drop power to 3 mA.
If the excitation channel is indexed, parameter 4
becomes an input location. The excitation
voltage must be loaded into the specified input
location before Instruction 22 is executed.
If the only requirement is the delay of program
execution, the excitation on time (parameter 2)
can be set to zero and the off time delay
(parameter 3) can be used.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Excitation channel
number
02: 4 Delay time that
excitation is on (0.01
sec)
03: 4 Delay time after
excitation is turned off
(0.01 sec)
04: 4 Excitation voltage
(millivolts)
or
Input location number,
when the excitation
channel (Param. 1) is
indexed (--)
Input locations altered: 0
Input locations read: 0 or 1
*** 23 BURST MEASUREMENT ***
FUNCTION
Instruction 23 will repeatedly make a voltage
measurement on a series of single-ended or
differential channels, applying excitation if desired.
The measurement units are millivolts prior to
scaling. The measurements saved can be those
made immediately upon execution of the
instruction or grouped around a specified trigger
condition. The results of the measurements may
be stored in Input Storage or the raw A/D data can
be sent out the serial port. The minimum sample
time per channel is 1.333 ms (i.e., one channel can
be sampled at a maximum rate of 750 Hz).
MEASUREMENT
The voltage measurement must use the fast
integration time of 272 µs. Differential
measurements are made with a single
integration. The noise level on a fast single-
ended or a differential measurement with 1
integration is 3 µV RMS. Thus, only the 25 mV
and greater voltage ranges are practical (range
codes 13-15).
Excitation is always supplied from excitation
channel 1. The excitation voltage in millivolts is
entered in Parameter 9. If excitation is not
desired, enter 0 for Parameter 9.
Three options are available for the first digit in
Parameter 4.
0 - Trigger on first measurement channel.
1 - Trigger on Digital Control Port 1.
2 - Trigger on first measurement channel, set
Digital Control Port high when trigger is met
and low when measurements have finished.
When triggering on options 0 or 2, the
measurement on the first specified channel
(Parameter 3) is compared to the limit specified
in Parameter 8. The user's multiplier and offset
are not applied before the comparison: the limit
must be entered in units of millivolts. If a digital
trigger (low < 1.5V, 3.5 V < HIGH < 5 V) is used,
it must be input to Digital Control Port #1.
Option 2 is useful when 2 or more CR10X's are
required to start "Bursting" at the same time.
For example, Digital Control Port #1 of all the
CR10X's involved are connected in parallel.
The master CR10X sets its Digital Control Port
#1 high when the trigger condition is met. The
remaining dataloggers, programmed with option
1, trigger on the digital signal. The master
CR10X sets Port #1 low when its
measurements are completed.