Sena STS Series User Manual page 47

If Send to recent unlisted remote host function is set as 'Yes', STS Series sends data to the
remote host, which has connected STS Series recently. Recent unlisted remote host is a remote
host, which has accessed a corresponding serial port of STS Series but is not configured on
remote host configuration. Surely, STS Series also send data to the hosts, which are configured
on remote host configuration. If Send to recent unlisted remote host function is set as 'No', STS
Series sends data only to the host(s) which are configured on remote host configuration. STS
Series maintains a recent unlisted remote host during the Inactivity Timeout.
Inactivity Timeout
In UDP mode, Inactivity Timeout is used in maintaining recent unlisted remote host. If there is no
data transmission between unlisted remote host and serial port of STS Series during Inactivity
Timeout, STS Series will not send data from a serial port to the recent unlisted remote host again.
Namely, Inactivity Timeout in UDP mode is the time maintained recent unlisted remote host list by
STS Series. If user set Inactivity Timeout as 0 in UDP mode, STS Series does not send any data
from serial port to unlisted remote host.
4.2.4.3. Modem emulation mode
In modem emulation mode, the serial port process acts as if it is a modem attached to the serial
device. It accepts AT modem commands and answers to them, as modems would do. It also handles
the modem signals correctly. Modem emulation mode is useful in the following cases.
- There already exists a modem attached to the users' serial device.
If users' serial device already has a modem for phone-line connection, it can be just replaced by
the STS Series for Ethernet connection. What users need to do is to use an IP address (or
domain name) instead of phone number as a parameter of ATA/ATDT commands.
- It is required to send serial data to the multiple remote hosts.
If the serial device should send data to the multiple hosts, modem emulation mode is required.
For example, the first data from the serial device can be sent to the first data acquisition server
and the second to the second server. What user device has to do is to change the IP address (or
domain name) parameter whenever the device sends ATD(T) XXX command.
By using the modem emulation mode of the STS Series, users can have their serial device connected
to the Ethernet network easily, which is cheaper than using phone line modem. Table 4-2 is a
summarized AT command table which is supported by the STS Series. Figure 4-7 shows the typical
case of the serial port command flow when ATDA command is used to connect to the Ethernet network.
47