User`s manual

Table Of Contents
OnCell G3111/G3151/G3211/G3251 Series User’s Manual Serial Port Operation Modes
4-8
3. Domain name with DDNS.
If your cellular service provider offers a public IP address after you connect to the cellular
network, you can also use the domain name to access the OnCell G3111/G3151/G3211/G3251.
You would need to register with a DDNS service provider and then enable the DDNS function
in the OnCell G3111/G3151/G3211/G3251. Please refer to Appendix C for more information.
4. Connecting TCP client and TCP server within the same cellular service provider.
In order to connect properly, the IP addresses of the two OnCell devices must belong to the
same subnetwork. To ensure that this is the case, use the same cellular service provider to
connect the devices to the network. In addition, you will need to request that the cellular
service provider provide you with two private IP addresses (e.g., 192.168.1.1 and
192.168.1.2).
TCP Client Modes
In TCP Client mode, the OnCell G3111/G3151/G3211/G3251 can actively establish a TCP
connection to a pre-defined host computer when serial data arrives. After the data has been
transferred, the OnCell G3111/G3151/G3211/G3251 can automatically disconnect from the host
computer by using the Inactivity time settings.
As illustrated in the figure below, data transmission proceeds as follows:
(1) The OnCell G3111/G3151/G3211/G3251, configured for TCP Client mode, requests a
connection to the host.
(2) Once the connection is established, data can be transmitted in both directions between the host
and the OnCell G3111/G3151/G3211/G3251.