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Configuration
Register address:
40001 or 0 (depends on PLC operation)
Number of registers
to retrieve:
a. 12
Note
: The number of registers is calculated from the number of sensors to be obtained x 2
(current value and last logged) x 2 (number of registers per float data type). In this example
the number of registers is 3 x 2 x 2 = 12.
Register data type:
Single precision float
The data retrieved by the PLC will be in the following order and have the meaning described in the table:
Holding Register
Register Address
Value
40001 – 40002
0 – 1
Current Wind Speed
40003 – 40003
2 – 3
Last logged Wind Speed
40005 – 40006
4 – 4
Current Wind Direction
40007 – 40008
6 – 5
Last logged Wind Direction
40009 – 400010
8 – 7
Current Temperature
400011 – 400012
10 – 11
Last logged Temperature
3.7.4
Example of iRIS acting as a protocol gateway (Modbus Slave)
This section describes how to use iLink to configure the iRIS to act as a gateway between a Modbus host (for example a
Programmable Logic Controller (PLC)) and HydroTel. The iRIS will operate as Modbus Slave and the PLC will read and
write values into holding registers that can be read and written too by HydroTel.
In this example there are three parameters for each direction. As the iRIS is acting purely as a gateway the type of
values/data represented by the parameters (e.g. water level, temperature, etc.) is irrelevant and hence not referred to in
the iRIS configuration. This will be defined in data originator (HydroTel and the PLC)
The example also assumes that the PLC has been wired to the Serial Sensor Interface which has been configured correctly.
Also, that appropriate settings for iRIS to HydroTel communications has been set to the iRIS and tested.
1. Connect to the iRIS with iLink and navigate to the configuration section.
2. Expand the
MODBUS DEVICES
branch and select the
+ ADD MODBUS DEVICE
option.
3. Give the device a name, this is used in the Virtual sensor configuration later.
4. Change the following:
Serial
Channel
Source:
SSI
Authority Roll:
Slave
Slave Address:
0
Endianness:
Little
