Jetter AG
Programming | 8
User Manual – JCM-501-E01
36 / 65
Receiving a
character
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 buf-
fer.
Sending a
character
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
character to the interface driver using the set communication parame-
ters.
4
The interface driver converts internal signal levels into the various in-
terface 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 buffer
and error bit
Framing error
is set.
The error counter is incremented.
Parity error
The parity bit of the received
character is not correct.
The erroneous character is stored
in the receive buffer and error bit
Parity error
is set. The error
counter is incremented.
Buffer overflow A character is received, al-
though the receive buffer is
full.
The character is discarded and er-
ror bit
Overflow
is set. The error
counter is incremented.
