XLINK 500/100 Operations & Maintenance Manual page # 151
15.11.
TCP/IP Session
A station equipped with a cell modem will use scheduled transmissions periodically connect to a
server and deliver sensor data. See the
and
details
.
Relevant settings include
Protocol, Main Server, Backup Server, Server Port, and Server Password.
When
Protocol
is set to
Hydromet Cloud,
the station will engage in handshaking with the server.
The station will provide the server with information about the transmission that includes the
station name, password, reason for the transmission, and error checking information. The server
will acknowledge the transmission.
If the server does not acknowledge the transmission, the station will retry the transmission until
it succeeds or until it times out.
When
Protocol
is set to
None,
the station will not engage in handshaking with the server.
If you are using a custom server, you will want to set
Protocol
to
None.
Either that or have the
custom server acknowledge the transmission.
15.11.1.
Hydromet Cloud Protocol
When the station connects to a server, some information is sent to the server before the sensor
data is delivered. This information is meant to help the server decide what to do with the sensor
data that is en route. The information includes details such as the sensor name and whether the
transmission is a result of an alarm event.
After the sensor data is delivered to the server, the server may log into the station and issue
commands to check status, change setup, download more data, or any other command line
activity.
15.11.2.
Course of Events for the Hydromet Cloud Protocol
1.
The station connects to main or backup server.
2.
The station sends Session Type Code<cr> (see below.)
3.
The station sends Station Name<cr>.
4.
The station sends Report Type Code<cr> to indicate purpose of connection (see below.)
5.
The station sends transmission data (if any) in whatever format the user chose, such as SHEF
or pseudobinary.
6.
The station sends ETX (0x03) to mark end of data.
7.
The station sends a 3 byte pseudobinary encoded CRC16 of previous data and the server
password (sometimes called Shared Secret.)
8.
The station waits for the server to either acknowledge or to initiate a command line session.
The server has 60 seconds to do either one.