KEPCO KLP Series (older -1200 models) Operator Manual - Manual (Page 56)

3-16
KLP073008
XOFF) the host controller can ensure that serial data interrupts occurring after parsing of the
incoming message do not result in lost data.
Figure 3-1 illustrates the default echo mode, the prompt method and the XON XOFF method
described in the following paragraphs.
Only four control characters (characters between 00
H
and 1F
H
) are acknowledged by the power
supply:
• Carriage Return (CR, 0D
H
)
• Line Feed (LF, 0A
H
)
• Back Space (BS, 08
H
)
• Escape (ESC, 01B
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 KLP
Power Supply by the command originator. When the line is parsed, the KLP sends the line ter-
minator sequence CR LF to the command originator.
The ESC character is used for synchronization, causing the KLP Power Supply to reset its input
buffer and return a CR LF sequence.
FIGURE 3-1. RS 232 IMPLEMENTATION
3.4.2.1 ECHO MODE
Echo mode is the default method of ensuring data is transferred without errors. Each byte (char-
acter) is echoed back to the sender where it is verified as the same character that was just sent.
If the character is incorrect or missing, the sender sends the character again until the correct
character is verified as having been received.
All non-control characters are sent via the serial port of the command originator. The control
character BS is echoed as BS Space BS. Only the first control character is returned in response
to either a CR LF or LF CR character sequence (see Figure 3-1).
3.4.2.2 PROMPT METHOD
The command originator sends a message line (command) to the KLP Power Supply and waits
until the prompt sequence CR LF > is received. The KLP sends the prompt sequence CR LF >
to the command originator indicating the power supply is ready to receive the next command so
that data will not be lost. The prompt method is similar to the echo method described above,
except that the command originator does not have to compare each character and repeat any
characters dropped. The operation of the KLP is identical for echo mode and prompt mode;
implementation of prompt mode is at the command originator.