Jetter JVM-104-O15, User Manual

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Jetter AG Programming | 7
JVM-104-O15 User Manual 26 / 60
Number Section Features
4 Receive register Read access to this register reads the re-
ceived characters in the receive buffer
(3).
5 Interface driver Converts internal signal levels into inter-
face signals.
6 Transmitter Performs parallel/serial conversion
7 Sending buffer Buffer for characters to be sent
8 Transmit register Write access to this register causes the
characters to be entered into the transmit
buffer (7) and to be sent by the transmit-
ter (6).
9 Status and control register Query of filling levels and error states of
buffers; setting of transmission parame-
ters
Tab. 21: Elements of the serial interface
Receiving a charac-
ter Receiving a character is done in 4 steps:
Step Description
1 The interface driver converts signals "on the line" into internal signal
levels and forwards them to the receiver.
2 The receiver performs serial/parallel conversion of this character and
checks the set communication parameters.
3 The receiver enters the character into the receive buffer if there is any
place left. Otherwise, the character is discarded and buffer overflow is
signaled.
4 Via receive register the character can be read out of the receive buffer.
Sending a charac-
ter A character is sent in 4 steps:
Step Description
1 Via transmit register the character is entered into the transmit buffer if
there is any place left. Otherwise the character is discarded.
2 Once the transmitter has sent a character, it reads the next character
from the transmit buffer.
3 The transmitter performs parallel/serial conversion and sends this char-
acter to the interface driver using the set communication parameters.
4 The interface driver converts internal signal levels into the various inter-
face standards
Error detection When receiving characters, the following errors are detected by the controller and
displayed in the register
Error state :
Errors Description Effect
Framing error The format of the received
character does not match the
set parameters. The erroneous character(s) is
(are) stored in the receive buf-
fer and error bit
Framing error
is set. The error counter is in-
cremented.