UM-0085-B09
DT80 Range User Manual
Page 246
RG
PPP Communications
About PPP
Point-to-Point Protocol (PPP) allows TCP/IP-based protocols to be run over the USB, Host RS-232 and/or serial sensor
port of the
DT80
.
The
DT80
operates as a PPP server. A client computer can connect to the
DT80
, via modem or direct cable, in much the
same was connecting to a dial-up Internet Service Provider. (Modem connections are only supported on the host RS232
port.) When a PPP connection is made, the
DT80
will, like an ISP, verify the supplied username and password and
allocate an IP address for the host PC to use for the duration of the session.
Each of the
DT80
's three PPP-capable ports has its own IP address, which is in turn different to the IP address for the
Ethernet port. This means that TCP/IP can potentially be active on all four ports simultaneously.
Note
For the USB port, the dataTaker
DtUsb
driver software is used to set up and manage a PPP connection in a simple manner.
See
for more details. There is no need for any of the PPP configuration described in this section if you are
using the USB port. This section is, however, still applicable if you plan to use a direct RS232 or modem connection.
While DT8xM models do use PPP to connect to the mobile network, there is no need for any of the PPPconfiguration
described in this section in order to use the integrated modem.
Setting up PPP
Setting up a PPP connection involves four main steps:
1.
Set or verify the required profile settings on the
DT80
2.
Install the physical communications link (RS232 cable, modem etc)
3.
Define a "modem device" on the host computer to represent the physical comms link
4.
Define a PPP "network connection" on the host computer, which will use the defined modem device
This normally needs to be done once only. Once the PPP network connection has been set up and saved on the host
computer, you can then establish a connection as and when required. This process is the same as you would use when
connecting to an Internet Service Provider via a dial-up connection. See Using PPP (P266).
1. DT80 Profile Settings
PPP Settings
The
DT80
's PPP settings can be listed using the
PROFILE
command:
PROFILE PPP
[PPP]
USER = DATATAKER
PASSWORD = DATATAKER
These show the username and password that the host computer must supply when establishing a PPP connection.
These profile settings can be changed in the usual way, e.g.
PROFILE PPP USER=DT
PROFILE PPP PASSWORD=SECRET
IP Addresses
Because PPP is used for a point-to-point connection between just two devices, it doesn't really matter what IP addresses
are chosen for each end – so long as the two addresses are different.
The
DT80
therefore uses a fixed IP address for each of its three serial ports, and allocates a fixed IP address to the host
computer at the other end of the link.
The IP addresses used by the
DT80
for PPP are as follows:
Interface
DT80
IP address
Host computer IP address
serial sensor port
1.0.0.1
1.0.1.1
host RS232 port
1.0.0.2
1.0.1.2
USB port
1.0.0.3
1.0.1.3
For example, if you establish a PPP connection to the host RS232 port then the
DT80
's IP address would be 1.0.0.2.
You could therefore access the
DT80
's web interface by entering
http://1.0.0.2
into a web browser, for example.
Comms Port Settings
The settings for the desired
DT80
port will also need to be set or checked. For example, if the host RS232 port is used
then the current settings can be queried using: