Campbell Scientific CR23X Micrologger - Manual (Page 156)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-22
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Reps (# of CD16AC
modules sequentially
addressed)
02: 2 Starting Address, Base 4
(00..33)
03: 4 Starting input location
Input locations read: 16 per repetition
*** 105 SDI-12 RECORDER ***
NOTE: Version 1.2 of the SDI-12
specification has been implemented in the
CR23X. Features added in this version are
marked with a dagger (†) and may not be
supported by older SDI-12 sensors.
Instruction 105 allows data to be collected from
SDI-12 sensors. The sensor’s SDI-12 data line
is connected to a control port (C5-C8). The
SDI-12 ground should be connected to a "G"
terminal on the CR23X wiring panel. SDI-12
power may be connected to 12V.
If multiple SDI-12 sensors are used, up to ten
sensors may be connected to a single control
port, but each sensor must have a unique
address and requires a separate Instruction
105.
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 4 Address (0-9, †10-
126)
02: 2 Command (Table 9-8)
03: 2 Control Port (C5-C8)
04: 4 Input Loc.
05: FP Mult
06: FP Offset
Input locations altered: 1-9 (†1-99), depending
on the SDI-12 sensor
Intermediate locations required: 21
PARAMETER 1. ADDRESS
Enter the address of the SDI-12 sensor (0-9).
†Extended addresses (10-126) may be used by
entering the decimal equivalent for the
appropriate ASCII character (see Appendix E).
For example, address ‘A’ would be entered as
65.
PARAMETER 2. COMMAND
Enter a number to select the command to be
sent to the SDI-12 sensor. Usually 0 is entered
to select the M command. The following
Standard SDI-12 commands are supported by
the CR23X:
TABLE 9-9. SDI-12 Command Codes
ENTRY COMMAND DESCRIPTION
0 M Initiate Measurement
0 -- C †Initiate Concurrent
Measurement
1..9 M1..M9 Additional
Measurement
commands specified
by the SDI-12 sensor
10 V Initiate Verify
sequence
11 I Send Identification
Command 0: the CR23X will issue the ‘M’ SDI-
12 measurement command and wait for the
sensor to complete its measurement before
requesting the data and proceeding to the next
instruction in the program table. If Instruction
105 is placed in Table 1, program execution will
be suspended during this delay. If it is placed in
Table 2, instructions in Table 1 may be
executed during this delay.
†Command 0--: this command enables
concurrent measurements with SDI-12 sensors
that support this feature. With concurrent
measurements, the CR23X can initiate
measurements with multiple SDI-12 sensors
without having to wait for each individual
sensor to complete its sequence before
proceeding to the next sensor. The CR23X will
issue the ‘C’ SDI-12 concurrent measurement
command and wait for the sensor response,
which includes the amount of time in seconds it
will take for the sensor to make the
measurement. The CR23X will not wait for the
data: rather, it will continue executing the table.
The next time the instruction is executed, the
CR23X will check the elapsed time. If the
elapsed time is equal to or greater than that
given by the sensor, the CR23X will get the data
from the SDI-12 sensor. In the following