3. Output string via the serial port (SerialOut() or SerialOutBlock() command).
o Example:
SerialOut(Com1,SerialOutString,"",0,100)
o Declare the output string variable large enough to hold the entire
concatenation.
o Example:
Public SerialOutString As String * 100
• SerialOut() and SerialOutBlock() output the same data, except that
SerialOutBlock() transmits null values while SerialOut() strings are
terminated by a null value.
7.9.17.5.4 Serial I/O Translating Bytes
One or more of three principle data formats may end up in the SerialInString()
variable (see examples in Serial Input Programming Basics
(p. 251) ). Data may be
combinations or variations of these. The instrument manufacturer must provide
the rules for decoding the data
• Alpha-numeric — Each digit represents an alpha-numeric value. For
example, R = the letter R, and 2 = decimal 2. This is the easiest protocol to
translate since the encode and translation are identical. Normally, the
CR1000 is programmed to parse (split) the string and place values in
variables.
Example string from humidity, temperature, and pressure sensor:
SerialInString = "RH= 60.5 %RH T= 23.7 °C Tdf= 15.6 °C Td=
15.6 °C a= 13.0 g/m3 x= 11.1 g/kg Tw= 18.5 °C H2O=
17889 ppmV pw=17.81 hPa pws 29.43 hPa h= 52.3 kJ/kg dT=
8.1 °C"
• Hex Pairs — Bytes are translated to hex pairs, consisting of digits 0 to 9 and
letters a to f. Each pair describes a hexadecimal ASCII / ANSI code. Some
codes translate to alpha-numeric values, others to symbols or non-printable
control characters.
Example sting from temperature sensor:
SerialInString = "23 30 31 38 34 0D"
which translates to
#01 84 cr
• Binary — Bytes are processed on a bit-by-bit basis. Character 0 (Null,
&b00) is a valid part of binary data streams. However, the CR1000 uses Null
terminated strings, so anytime a Null is received, a string is terminated. The
termination is usually premature when reading binary data. To remedy this
problem, use SerialInBlock() or SerialInRecord() when reading binary data.
The input string variable must be an array set As Long data type, for
example:
Dim SerialInString As Long
7.9.17.5.5 Serial I/O Memory Considerations
Several points regarding memory should be considered when receiving and
processing serial data.
253
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