Campbell Scientific CR800 and CR850 Measurement and Control Systems - Manual (Page 205)

Section 7. Installation
205
+3 to +25 with ‐3 to + 3 defined as the transition range that contains no
information. A mark is a logic 1 and negative voltage. A space is a logic 0
and positive voltage.
MSB
Most significant bit (the leading bit).
RS‐232C
Refers to the standard used to define the hardware signals and voltage
levels. The CR800 supports several options of serial logic and voltage
levels including RS‐232 logic at TTL levels and TTL logic at TTL levels.
RX
Receive
SP
Space
Start bit
Is the bit used to indicate the beginning of data.
Is the end of the data bits. The stop bit can be 1, 1.5 or 2.
TX
Transmit
7.8.8.5 CRBasic Programming
To transmit or receive RS-232 or TTL signals, a serial port (see table CR800
Serial Ports
(p. 203)
) must be opened and configured through CRBasic with the
SerialOpen() instruction. The SerialClose() instruction can be used to close the
serial port. Below is practical advice regarding the use of SerialOpen() and
SerialClose(). Program CRBasic example Receiving an RS-232 String
(p. 211)
shows the use of SerialOpen(). Consult CRBasic Editor Help for more
information.
SerialOpen (COMPort,BaudRate,Format,TXDelay,BufferSize)
• COMPort — Refer to CRBasic Editor Help for a complete list of COM ports
available for use by SerialOpen().
• BaudRrate — Baud rate mismatch is frequently a problem when developing
a new application. Check for matching baud rates. Some developers prefer to
use a fixed baud rate during initial development. When set to -nnnn (where
nnnn is the baud rate) or 0, auto baud-rate detect is enabled. Autobaud is