Campbell Scientific CR7 Measurement and Control System - Manual (Page 19)

CR7 MEASUREMENT AND CONTROL SYSTEM OVERVIEW
OV-9
OV3.4 INSTRUCTION FORMAT
Instructions are identified by an instruction
number. Each instruction has a number of
parameters that give the CR7 the information it
needs to execute the instruction.
The CR7 Prompt Sheet has the instruction
numbers in red, with the parameters briefly
listed in columns following the description.
Some parameters are footnoted with further
description under the "Instruction Option Codes"
heading.
For example, Instruction 73 stores the
maximum value that occurred in an Input
Storage Location over the output interval. The
instruction has three parameters (1)
REPetitionS, the number of sequential Input
Storage locations on which to find maxima, (2)
TIME, an option of storing the time of
occurrence with the maximum value, and (3)
LOC the first Input Storage Location operated
on by the Maximum Instruction. The codes for
the TIME parameter are listed in the "Instruction
Option Codes".
The repetitions parameter specifies how many
times an instruction's function is to be repeated.
For example, four 107 thermistor probes, wired
to single-ended channels 1 through 4, are
measured using a single Instruction 11, Temp-
107, with four repetitions. Parameter 2
specifies the input channel of the first thermistor
(channel 1) and parameter 4 specifies the Input
Storage Location in which to store
measurements from the first thermistor. If
Location 5 were used, the temperature of the
thermistor on channel 1 would be stored in Input
Location 5, the temperature from channel 2 in
Input Location 6, etc.
Detailed descriptions of the instructions are
given in Sections 9-12.
OV3.5 ENTERING A PROGRAM
Programs are entered into the CR7 in one of
four ways:
1. Keyed in using the CR7 keyboard.
2. Loaded from a pre-recorded listing using
the *D Mode. There are two types of
storage/input:
a. Stored on disk/sent from computer
(PC208 software).
b. Stored/loaded from SM192/716 Storage
Module
3. Loaded from Storage Module or internal
PROM (special software) upon power-up.
A program is created by keying it directly into
the datalogger as described in the following
Section, or on a PC using the PC208
Datalogger Support Software.
PC208 Software programs are used to develop
and send programs to the CR7. Program files
developed can be downloaded directly to the
CR7 via direct wire, telephone, or Radio
Frequency (RF).
Programs on disk can be copied to a Storage
Module. Using the *D Mode to save or load a
program from a Storage Module is described in
Section 1.8.
If the SM192/716 Storage Module is connected
when the CR7 is powered-up, the CR7 will
automatically load program number 8, provided
that a program 8 is loaded in the Storage
Module (Section 1.8).
It is also possible (with special software) to
create a PROM (Programmable Read Only
Memory) that contains a datalogger program.
With this PROM installed in the datalogger, the
program will automatically be loaded and run
when the datalogger is powered-up, requiring
only that the clock be set.
OV4. PROGRAMMING EXAMPLE
The best way to become acquainted with the
CR7 is to program it and make some
measurements. If your CR7 contains either a
723 or 723-T Analog Input card, a short
copper-constantan thermocouple (TC) should
be connected to channel 5. In this example, you
will program the CR7 to sample the
thermocouple temperature. If you have not
purchased the 723-T with a Resistive
Temperature Device (RTD) to measure the TC
reference junction temperature, a "dummy"
reference temperature will be used.