SENA LS100W - Manual (Page 42)

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The purpose of the DTR/DSR pin is to emulate modem signal control or to control TCP connection
state by using serial port signal. The DTR is a write-only output signal, whereas the DSR is a read-only
input signal in the LS100W side.
The DTR option can be set to one of three types: always high, always low or show TCP connection. If
the DTR behavior is set to show TCP connection, the state of the DTR pin will be maintained high if
the TCP connection is established.
The DSR option can be set to one of three types: none, allow TCP connection only by high or
open/close TCP connection. Allow TCP connection only by HIGH is valid only if host mode is TCP
server or equivalent. If this option is set, the incoming TCP connection request will be accepted only
when the DSR signal is high state. Open/close TCP connection is valid only if the host mode is a TCP
client or equivalent. If the DSR behavior is set to open/close TCP connection, the high state of the
DSR pin will make the LS100W send a connection request to the specified destination host, whereas
the low state close a connection.
Inter-character timeout defines the interval that the LS100W fetches the overall serial data from its
internal buffer. If there is incoming data through the serial port, the LS100W stores data into the
internal buffer. The LS100W transfers data stored in the buffer via TCP/IP, only if the internal buffer is
full or if the inter-character time interval reaches to the time specified as inter-character timeout.
Optimal inter-character timeout would be different according to your application but at least it must be
larger than one character interval within specified baud rate. For example, assume that the serial port
is set to 1200 bps, 8 Data bits, 1 stop bit, and no parity. In this case, the total number of bits to send a
character is 10 bits and the time required to transfer one character is
10 (bits) / 1200 (bits/s) * 1000 (ms/s) = 8.3 ms.
Therefore, you have to set inter-character timeout to be larger than 8.3 ms. The inter-character
timeout is specified in milliseconds and must be larger than 10 ms.
If users want to send the series of characters into a packet, serial device attached to the LS100W
should send characters without time delay larger than inter-character timeout between characters and
the total length of data must be smaller than or equal to the LS100W internal buffer size. The serial
communication buffer size of LS100W is 1400 bytes.
Figure 5-1 shows serial port configuration example of 9600 bps, 7 data bits, even parity, 2 stop bits,
hardware flow control, DTR shows TCP connection, No DSR behavior and inter-character time out of
10 ms:
> set serial 9600 7 e 2 h s n 10
OK
>
Figure 6-1 Serial port configuration