Sutron Corporation X-Link Operations & Maintenance Manual, Rev 1.63 5/24/2016 pg. 62
It allows stations to go into lower power mode than if
Listening
were
enabled.
5.8.
Optimizing Data Usage
The data contained in the transmission is largely dependent on the user setup
variable
Tx Data Content
and the
Tx Interval
.
Each transmission contains data
since the last transmission.
X-Link can transmit no more than one kilobyte (1KB) of data at a time. If X-Link is
unable to transmit all the required data, change the
Tx Interval
to make
transmissions more frequently. If all the data designated for transmission cannot
fit, it will never be transmitted! Increase transmission frequency by decreasing
the
Tx Interval
, decrease the amount of data that goes into transmissions, or use
a more compact
Tx Format.
One kilobyte of data will hold almost 150 SHEFFIX
formatted sensor readings, which is far more than most environmental
situations require.
5.8.1.
Data Usage for Internet
There is significant overhead when delivering the data over the internet. This
due to the nature of TCP/IP communications. GPRSLink, HSPALink, and
CDMALink will suffer from these overheads when data is sent to and from X-Link.
Transmitting roughly 500 bytes of sensor data will result in approximately one
kilobyte of total data being sent on the network.
Just being connected to the internet in listening mode does not carry any data
charges.
5.8.2.
Data Usage for Messages
Sometimes X-Link will send messages. GPRSLink, HSPALink, and CDMALink can
be set up to use SMS to deliver sensor data. IRIDIUMLink always transmits
messages.
The costs for sending messages are on a per message basis. One message will
cost the same no matter how much data is in it.
Each SMS is limited to 160 bytes of data.
Iridium packets can be no larger than 340 bytes.
A single message can only hold a limited amount of data. If there is more data
than can fit, multiple transmissions will have to be sent.
In order to receive the
freshest data, the
Tx Interval
should be set such that only one message is sent
at one time.
Given the choice of getting one transmission every 15 minutes or
getting two back-to-back transmissions every 30 minutes, opt for the 15 minute
data. The price is the same, but the data is refreshed more frequently. This only
applies to IRIDIUM and SMS transmissions.
