Esempio di applicazione
con TCP-Com
Trimble is a leading innovator of Global Positioning System (GPS)
technology. Trimble manufactures an integrated GPS survey system
called a GPS Total Station 5700. This is used in remote sites to
collect survey information and the information can be automatically
transmitted from a 5700 ROVER to a 5700 BASE station using an
AirLink Raven II CDPD (Cellular Packet Data) Modem and a "Wireless
IP" service.
AirLink is a leading provider of wireless connectivity products
for remote devices enabling real-time data collection. The CDPD
Raven II modem is designed for commercial applications and is the
perfect choice for Telemetry, SCADA, AVL/Dispatch and Public Safety
applications with its rugged industrial design. It is sometimes
necessary to connect multiple 5700 ROVERS to one 5700 BASE
simultaneously. The Host CDPD Modem cannot support multiple
simultaneous TCP sessions. However, by using TCP-Com as a
software-based terminal server it is possible for multiple Trimble
5700 ROVERS to communicate over AirLink CDPD Modems and the
Internet.
Using TCP-Com, you can
attach a DGPS server such as the 5700 BASE (or any other RS232
device) to the serial port of a Windows PC and have that data
available anywhere over any TCP/IP based network - including the
Internet. Given that CDPD networks are all connected to the
Internet, connecting a 5700 BASE to a PC with an Internet connection
running TCP-Com can make that data available to any 5700 ROVERS
equipped with CDPD Modems.
TCP-Com can be
described as a software based terminal server. Much like a physical
terminal server, TCP-Com acts as middleware lying in-between a
physical serial port and a TCP/IP network. Data that comes into the
serial port is passed to connections made to the TCP side. TCP-Com
can accept connections from multiple TCP clients, allowing data from
a device connected to the serial port to be sent to more than one
client at the same time. In this case, the clients for TCP-Com are
handheld Trimble Survey Controllers with the 5700 ROVERS.
TCP-Com Set Up
TCP-Com is set up with the serial
port settings matching those of the 5700 BASE. It is set up as a TCP
Server with the IP address as the Public IP Address. The TCP port
can be set to any number. It is also set up to allow multiple client
connections to allow multiple ROVERS to connect to a single BASE.
Then the setting to send inbound serial data to all TCP/IP clients
is selected as this is the key to distributing the RS232 data from
the 5700 BASE to every 5700 ROVER. Once TCP-Com is activated it is
then possible to connect to it from anywhere on the CDPD network or
the Internet. As soon as a successful connection is made from any
remote ROVER via CDPD this is displayed in TCP-Com.
5700 ROVER
Connection via CDPD to TCP-Com
The ROVER controller should be
configured using a cellular modem, however instead of dialing a
phone number it dials an IP address and TCP Port - specifically
those of the TCP-Com server, i.e., 166.148.11.123/12345 where the
first part is the IP address followed by a "/" and the port number (here
12345)
Once the ROVER survey controller is started it is necessary to set
the ROVER radio as a Cellular Modem (under "Radio Type").
5700 BASE is just set up to communicate with the PC running TCP-Com
via its RS232 connection. Once connected, the 5700 BASE will be
transmitting data into the serial port of the PC. TCP-Com will
listen on the Com Port for the data, taking it and passing it into
the TCP stack. The data is then made available to any ROVER making a
TCP connection to the TCP-Com server. Once the Trimble Survey
Controller at the 5700 BASE is powered up the survey can be started
and data will be sent to the TCP-Com server. Then all the Trimble
Survey Controllers with the 5700 ROVERS can be powered up to
communicate via the ROVER CDPD Modem. Once the survey is started the
TCP-Com server is dialed as described above and the connection is
made. Once connected, data will be passing from out of the PC (running
TCP-Com) over the TCP connection to the ROVERs. Each ROVER will
indicate on its screen that it is in fact receiving data from the
BASE. At this point, any of the survey operations can be performed.
TCP-Com Benefits
-
TCP-Com
allows multiple 5700 ROVER units to be connected to one BASE. It
can do this as it allows connections from multiple TCP/IP clients
simultaneously.
-
This
makes it possible to perform surveys in multiple locations
simultaneously.
-
With TCP-Com's
and the Survey Controller's ability to communicate over TCP/IP
survey data can be collected in real-time from anywhere where a
cell phone can be used to call up the CDPD carrier and communicate
over the Internet.
-
TCP-Com
is cost effective and very easy to set up and use.
Conclusion
The combination of the Trimble GPS
Total Station 5700, an AirLink Raven II CDPD Modem and TCP-Com
allows survey information to be collected in real-time from many
remote survey sites.
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