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5.9
Network communication: getting started
Once it has the correct Modbus address and communication settings, 16131.5 can be connected
directly to an RS-485 network and a power supply.
Installing a 16131.5 in the network also requires configuring the communication for this new Modbus
device. This usually consists of defining a request that can be broadcast by the master.
Typical operation requires the master to make a request of irradiance data in registers 31501 + 31502
every 1 second, and store the 60 second averages. The data format of register 31501 + 31502 is a
signed 32 bit integer.
Note:
Up to five 16 bit registers can be requested in one request. In case six or more registers are
requested in just one request, 16131.5 will not respond. If requesting six or more registers, multiple
requests should be used: 16131.5 will respond as expected.
5.10 Adapting the Modbus address and communication settings
Setting the instrument address and baud rate can be done in different ways:
•
by connecting the sensor to the PC and using a Modbus testing tool. There are links to
different solutions available at
•
by using the available network user interface software.
The Modbus address is stored in register 40001 and has a default value of 11. A user may change the
address to a value in the range of 1 to 247. The address value must be unique in the network. The
baud rate is stored in register 40200.
The default communication frame is 19200 baud, with even parity bit, 8 data bits and 1 stop bit. After a
new address or communication setting is written the sensor must be restarted.
