A CR6 or CR1000X data logger programmed as a Modbus Master can retrieve the values stored in
the Input Registers. To do this, the CRBasic program requires a
SerialOpen()
instruction
followed by the
ModbusMaster()
instruction.
The
SerialOpen
instruction has the following syntax:
SerialOpen
(ComPort, Baud, Format, TXDelay, BufferSize, Mode)
The
Format
is typically set to logic 1 low; even parity, one stop bit, 8 data bits. The
Mode
parameter should configure the ComPort as RS-485 half-duplex, transparent. The
ModbusMaster()
instruction has the following syntax:
ModbusMaster
(Result, ComPort, Baud, Addr, Function, Variable, Start, Length,
Tries, TimeOut, [ModbusOption])
The
Addr
parameter must match the sensor Modbus address. To collect all of the values, the
Start
parameter needs to be 1 and the
Length
parameter needs to correspond with the
register count (see
(p. 7)).
ModbusOption
is an optional parameter
described in the CRBasic Editor Help. Refer to
(p. 12) for more
information.
10. Maintenance and
troubleshooting
The MS-80M has no service items requiring scheduled replacement. There is no accessible
desiccant cartridge to maintain. Use pure alcohol or distilled water and a lint-free cloth to clean
the dome, removing smears and deposits. Local conditions and application dictate cleaning
interval. Sophisticated research applications require daily cleaning. For typical PV applications,
clean once per week, bi-monthly, or monthly. The MS-80M should be recalibrated following
industry standard best practices such as ASTM G167, ISO 9846, ASTM E824 or ASTM G207 by an
accredited lab. The recommended recalibration interval is two years. Contact Campbell Scientific
for more information.
Unexpected results typically occur because of improper wiring or programming, electromagnetic
radiation, or damaged cables. Ensure that the data logger program includes the correct
parameters for the measurement instructions. Check for the presence of strong sources of
electromagnetic radiation and use the 50 or 60 Hz integration option in the data logger program
MS-80M Secondary Standard Pyranometer with RS-485 Modbus Communication
9
