Campbell-scientific CR800 and CR850 Measurement and Control Systems Manual de usuario descargar pdf (Pagina 211)

100

101

Section 7. Installation

211

the sensor sends multiple strings at once, consider declaring a single string

variable and read incoming strings one at a time.

TheCR800adjuststhedeclaredsizeofstrings.Onebyteisalwaysadded

tothedeclaredlength,whichisthenincreasedbyuptoanotherthree

bytestomakelengthdivisiblebyfour.

Declaredstringlength,notnumberofcharacters,determinesthe

memoryconsumedwhenstringsarewrittentomemory.Consequ

ently,

largestringsnotfilledwithcharacterswastesignificantmemory.

7.8.8.5.6 Demonstration Program

CRBasic example Receiving an RS-232 String

(p. 211) is provided as an exercise in

serial input / output programming. The example only requires the CR800 and a

single wire jumper between COM1 Tx and COM2 Rx. The program simulates a

temperature and relative humidity sensor transmitting RS-232 (simulated data

comes out of COM1 as an alpha-numeric string).

CRBasicExample40. ReceivinganRS‐232String

'To demonstrate CR800 Serial I/O features, this program simulates a serial sensor

'by transmitting a serial string via COM1 TX. The serial string is received at

'COM2 RX via jumper wire. Simulated air temperature = 27.435 F, relative humidity = '56.789%.

'Wiring:

'COM1 TX (C1) ----- COM2 RX (C4)

'Serial Out Declarations

Public TempOut As Float

Public RhOut As Float

'Declare a string variable large enough to hold the output string.

Public SerialOutString As String * 25

'Serial In Declarations

'Declare a string variable large enough to hold the input string

Public SerialInString As String * 25

'Declare strings to accept parsed data. If parsed data are strictly numeric, this

'array can be declared as Float or Long

Public InStringSplit(2) As String

Alias InStringSplit(1) = TempIn

Alias InStringSplit(2) = RhIn

'Main Program

BeginProg

'Simulate temperature and RH sensor

TempOut = 27.435 'Set simulated temperature to transmit

RhOut = 56.789 'Set simulated relative humidity to transmit

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Campbell-scientific CR800 and CR850 Measurement and Control Systems Manual de usuario Pagina 211

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