Specifications

OPERATIONS
Page 91 MRC-565 Packet Data Radio Operations & Maintenance
For example:
02/21/14 12:22:05 Command response received from 00500
# 02/21/14 12:19:54 CPU:CR1000.CR1 Downloaded to PakID:00001 OK
Note that the PakID is the ID of the data logger attached to the destination radio.
5.9 SDI-12 Sensors
Support for collecting data from sensors using the SDI-12 protocol is described in this document
in three sections. These are:
1. Data Collection
2. Data Logging
3. User Interface.
5.9.1 Data Collection
The data collection process usually requires a smart processor to connect to each data logger and
extract the recorded data. In many cases the data loggers have the required software to access
sensors and perform the calculations to convert the reading into engineering data values. Sensor
development has led to devices that do their own data calculations and use the simple SDI-12
protocol to send that data to data recorders.
The MRC-565 radio can collect data from SDI-12 sensors then transmit it to the central data
system. This is usually done on a periodic basis, every hour for example. The radio organizes the
data measurements into message packets called Sensor Data (SDATA) Reports for transmission
to a master station. Each SDATA report can hold from 1 to 16 data values of 16 bits each. These
can be in integer (hex) or CSI-Floating-point format. Each SDATA report has a unique group
number (0-15) and data/time tag. The 565 radio can hold up to 200 of these group reports while
waiting for meteor trail communication opportunities to deliver them to the master station, or
during brief network outages.
5.9.2 Setup
This section gives a general description of how the radio’s commands are used to adapt the radio
to the SDI-12 paradigm used by the sensors. The User Interface section below gives the details
of each radio command.
The radio commands define a Sensor Definition Table and create a data collection and
transmission schedule. The SDI-12 protocol is used to give the radio control of and access to the
sensors and their data measurements. The sensors also require commands to configure and
calibrate them. The sensor setup will be described by the documentation provided by each
Manufacturer and is not discussed here.