LIN101
RS232 / LAN INTERFACE
ELPRO Video Labs s.r.l.
Via della Praia 4/a FERRIERA di BUTTIGLIERA ALTA (TO) - ITALY
Tel. +39 0119348778 - FAX +39 0119348779
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The LIN101 provides a way to choose which incoming serial data is accepted into the serial -> Ethernet
buffer, how this data is combined into Ethernet packets and when it is sent out via the Ethernet port.
The LIN101 treats all incoming serial data as a sequence of data blocks. The term “data block” here does not mean that
the LIN101 is only capable of working with a structured serial data. An absolutely random serial stream can also be
processed- as one continuous infinite serial data block. Serial data blocks begin when a
start condition
is detected and
end when a
stop condition
is detected. After the start condition is detected the LIN101 begins recording the incoming
serial data into the serial -> Ethernet buffer. Thus, the start condition is said to
open
the serial data block. When the stop
condition is detected the LIN101 seizes recording the data into the buffer and attempts to send out all the data
accumulated in the buffer via the Ethernet port. Therefore, the stop condition
closes
the serial data block. The inter-block
serial data i.e. the data received after the stop condition is detected and before the next start condition is detected is
discarded. Besides the start and stop conditions there is also a
break conditio
n. When the break condition is detected the
LIN101 doesn’t close the serial data block (i.e. it continues recording subsequent serial data into the serial -> Ethernet
buffer) but sends out the data already accumulated in the buffer through the Ethernet port. Break conditions provide a
way to subdivide large serial data blocks.
4.1 Start conditions
The Start On Any Character Setting defines if the LIN101 recognizes any character received into the serial port as a start
condition or requires a predefined Start Character to open the serial data block.
When Start On Any Character is set to “yes” the LIN101 will accept any character following the end of the previous serial
data block as the beginning of the next block. When Start On Any Character is set to “no” the LIN101 will only open the
serial data block when one of the preset Start Characters is received. Up to three different Start Characters can be
defined. Start Characters received after the serial data block has been opened are treated as normal characters and do
not “restart” the serial data block.
4.2 Stop conditions
Up to three different Stop Characters can be defined to close the serial data block. Once one of the preset Stop
Characters is detected the LIN101 closes the serial data block and attempts to send out the contents of the serial ->
Ethernet buffer via the Ethernet port. All subsequent serial data is ignored until the next start condition is met.
The use of Start Characters and Stop Characters assumes that these characters will not be encountered in the data
block body. Some communications protocols use checksums (or other forms of data integrity verification). Checksum can
potentially take any value and occasionally match the ASCII codes of the Stop Characters.
To avoid possible confusion some communications protocols put the checksum bytes
behind
the Stop Characters. The
LIN101 deals with this by allowing to define a Number Of Post-characters for each enabled Stop Character. For example,
if the Number Of Post-characters for a certain Stop Character is set to 2 then the LIN101 will additionally receive and
count as belonging to the current serial data block 2 bytes of data after this Stop Character has been encountered.
4.3 Break conditions
The Maximum Data Length Setting defines the maximum number of data bytes in the serial -> Ethernet buffer. (can be
set between 32 and 255). Once this number is reached the LIN101 attempts to send out the contents of the buffer via the
Ethernet port. This Setting only works when the UDP/IP Transport Protocol is selected. This is because TCP/IP has its
own way to determine what size of data chunks is best for transmission over the network.
The Maximum Intercharacter Delay Setting defines the maximum time gap between the arrival of two consecutive serial
characters into the serial port (can be defined in 10ms increments between 10ms and 2.55 sec). Once this time is
exceeded the LIN101 attempt to send out the contents of the serial -> Ethernet buffer via the Ethernet port. Setting the
maximum Intercharacter Delay to 0 disables the function.
4.4 Default configuration
The default configuration is the follow:
•
Start On Any Character
•
no
Stop Characters
are defined
•
Maximum Intercharacter Delay
is 10 ms
•
Maximum Data Length
is 255 byte (UDP only).