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3.5.6.2
RS 232 IMPLEMENTATION
The following paragraphs are provided to help the user understand how the RS 232 serial inter-
face is implemented in the BOP. Since the RS 232 protocol does not use a parity bit, The
XON/XOFF method of communication is selected as the default to ensure "handshake" control
of serial communication.
The echo mode is an optional method used to ensure reliable communication between the com-
mand originator (computer) and the BOP power supply, thus avoiding a more complex "hand-
shake" protocol. When the BOP is in the RS 232 echo mode it returns all data sent to the host
controller.
The BOP provides an additional option that allow handshake communication: the Prompt
method. By using the handshake options (prompt and XON XOFF) the host controller can
ensure that serial data interrupts occurring after parsing of the incoming message do not result
in lost data.
Figure 3-17 illustrates the echo mode, the prompt method and the default XON XOFF method
described in the following paragraphs.
Only seven control characters (characters between 00
power supply:
•
Carriage Return (CR, 0D
•
Line Feed (LF, 0A
•
Back Space (BS, 08
•
Escape (ESC, 01B
•
XON (011
•
XOFF (013
•
CAN (018
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 BOP
BOP HIPWR 080709
FIGURE 3-17.
RS 232 IMPLEMENTATION
)
H
)
H
)
H
)
H
)
H
)
H
)
H
and 1F
) are acknowledged by the
H
H
3-49
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