RST Instruments RSTAR L900 Series, Instruction Manual

Page: 18 / 22

L900 RSTAR Array Radio Series System
Instruction Manual
ELM0077I
RST Instruments Ltd. Page 14
D
ETERMINE
RSTAR L
ISTENING
S
TATE
Use the following command to determine the RSTAR listening state:
‘QT<CR>’
The RTU will respond with
‘,1,
...’ Or ‘
,0,…
’ indicating outside or inside RSTAR
listening interval respectively.
This function can be used to make sure that all possible data is collected before
retrieving data from the RTU.
R
ETRIEVING
D
ATA FROM THE
RTU
M
ODBUS
M
ASTER
Data for each DT logger type can be queried from the RTU using MODBUS function
4 (read coils). The MODBUS addresses for different logger types are summarized in
Table A-1.
For each logger of a requested type, the RTU will return 10 diagnostic fields, then the
sensor data. As an example, for a network of two DT2011B Node Loggers: the first
10 returned values will be diagnostic from the first Node DT2011B, the next two
channels will be sensor data from first Node DT2011B, the next 10 channels (13
th
through 22
nd
inclusive) will be diagnostic data from the second Node DT2011B, and
the 23
rd
and 24
th
values will be the sensor data from the second Node DT2011B. See
Table 4-1 for the identities of each the diagnostic fields.
M
ODBUS
M
ASTER IN
C
AMPBELL
D
ATA
L
OGGERS
The Following is a general case use of the MODBUS master function for Campbell
Scientific Loggers:
‘ModbusMaster (<ModbusResultVar>,<ComPort>,115200,<Modbus
Address>,4,<TargetDataArray>,1,<totalChannels> ,3,100)’
Contact RST if the total channels is greater than 720.