4-10
BIT 4886 051010
FIGURE 4-4. RS 232 IMPLEMENTATION
Only seven control characters (characters between 00
H
and 1F
H
) are acknowledged by the BIT
4886:
• Carriage Return (CR, 0D
H
)
• Line Feed (LF, 0A
H
)
• Back Space (BS, 08
H
)
• Escape (ESC, 01B
H
)
• XON (011
H
)
• XOFF (013
H
)
• CAN (018
H
)
BS deletes the last character entered, with the exception of CR or LF characters. Either the CR
or LF character acts as the line terminator, initiating parsing of the ASCII data sent to the BIT
4886 by the command originator. When the line is parsed and the commands are sent to the
analog processor, the BIT 4886 sends the line terminator sequence CR LF to the command
originator.
The ESC character is used for synchronization, causing the BIT 4886 to reset its input buffer
and return a CR LF sequence.
The XON character enables the transmitter if XON/XOFF flow control is enabled (see PAR.
4.5.2.2).
The XOFF character stops data transmission if XON/XOFF flow control is enabled (see PAR.
4.5.2.2).
The CAN character resets the receive and transmit pointers and queues.
CAUTION: When the serial port has received an XOFF, the error message
-400, QUE
error
will be placed in the queue to indicate the loss of transmitted informa-
tion due to a received XOFF character. When XON is received, the unit will
transmit all data in it's buffer followed by the exclamation character (!). This
(!) character is not part of any message from the BIT 4886 and indicates the
transmission buffer has been cleared and the BIT 4886 is idle.
