Campbell CR800 Series, Operator'S Manual

Page: 176 / 598

Section 7. Installation
176
7.7.1.4 Miscellaneous Features
CRBasic example
Miscellaneous Program Features
(p. 176)
shows how to use
several CRBasic features: data type, units, names, event counters, flags, data-
output intervals, and control statements.
Miscellaneous Program Features
'This program example demonstrates the use of a single measurement instruction. In this
'case, the program measures the temperature of the CR800 wiring panel.
Public RefTemp 'Declare variable to receive instruction
BeginProg
Scan (1,Sec,3,0)
PanelTemp (RefTemp,250) 'Instruction to make measurement
NextScan
EndProg
'A program can be (and should be!) extensively documented. Any text preceded by an
'apostrophe is ignored by the CRBasic compiler.
'One thermocouple is measured twice using the wiring panel temperature as the reference
'temperature. The first measurement is reported in Degrees C, the second in Degrees F.
'The first measurement is then converted from Degree C to Degrees F on the subsequent
'line, the result being placed in another variable. The difference between the panel
'reference temperature and the first measurement is calculated, the difference is then
'used to control the status of a program control flag. Program control then
'transitions into device control as the status of the flag is used to determine the
'state of a control port that controls an LED (light emitting diode).
'Battery voltage is measured and stored just because good programming practice dictates
'it be so.
'Two data storage tables are created. Table “OneMin” is an interval driven table that
'stores data every minute as determined by the CR1000 clock. Table “Event” is an event
'driven table that only stores data when certain conditions are met.
'Declare Public (viewable) Variables
Public Batt_Volt As FLOAT 'Declared as Float
Public PTemp_C 'Float by default
Public AirTemp_C 'Float by default
Public AirTemp_F 'Float by default
Public AirTemp2_F 'Float by default
Public DeltaT_C 'Float by default
Public HowMany 'Float by default
Public Counter As Long 'Declared as Long so counter does not have
'rounding error
Public SiteName As String * 16 'Declared as String with 16 chars for a
'site name (optional)
'Declare program control flags & terms. Set the words “High” and “Low” to equal “TRUE”
'and “FALSE” respectively
Public Flag(1) As Boolean
Const High = True
Const Low = False