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MIW-SPS-EN-001 - 29 / 11 / 2018
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Fig. 10 Sensor calibration and
Modbus register reset tact switch
Fig. 11 Sensor calibration / Modbus register
reset / normal operation indication
2.
Reset of Modbus Registers procedure:
Press button SW2 for 4 seconds until the blue LED on the printed circuit board
(
Fig. 11
) blinks twice and keep pressing the button until it blinks three times. The
Modbus registers are restored to their default values (factory preset).
NOTE
Do not release SW2 button after the LED (
Fig. 11
) blinks twice until it blinks again
three times. Otherwise the SPS pressure transmitter will carry out a calibration
procedure instead of Modbus registers reset procedure.
NOTE
Continuous rapid blinking of the blue SMD LED (
Fig. 11
) indicates normal operation
of the microprocessor.
ATTENTION
The status of the LEDs can be checked only when the unit is energised. Take the
relevant safety measures!
3.
Factory preset values of the parameters:
The sensor data is arranged in two sectors: input registers and holding registers. The
input registers contain the measured sensor data and the current analog / digital
output. The holding registers contain all the settings.
INPUT REGISTERS
(see
Table
Modbus register maps
)
Input registers are read-only. They contain the measured data. It is stored from
address 1 (30001) to address 8 (30008). The other input registers are not used with
this unit; when these registers are addressed, they return 0.
All the data can be read using the command “Read Inputs Registers”.
Table
Modbus
register maps
shows the returned data type and the way it should be interpreted.
For example the reading 1.000 in register 1 means that the measured differential
pressure is 1.000 Pa, reading 100 in register 2 means that the analog / digital output
is 10,0 % of the full scale.
■
Input registers 3 and 4
are “Max. Pressure Limit Flag” and “Min. Pressure
Limit Flag”.
►
“Max. Pressure Limit Flag” is set to
'
1
'
when the pressure is above the maximum
limit defined by holding register 14, and it is set to
'
0
'
when the pressure is
below this limit.
►
“Min. Pressure Limit Flag” is set to
'
0
'
when the pressure is above the minimum
limit defined by holding register 15, and it is set to
'
1
'
when the pressure is below
this limit. An update of these registers occurs after the Power-up time (defined
by holding register 16) expires.
■
Input registers 5
(and input register 6 with SPS-X-6K0) give(s) information about
the current air volume flow rate (if the K-factor of the used fan / drive is known).
For instance 1.000 in this register means that current air volume flow rate is 1.000
m
3
/h (for SPS-X-2-K0). The value in this register is equal to the K-factor of the motor
(holding register 17) multiplied by square root of the measured differential pressure.
SPS
DIFFERENTIAL PRESSURE
TRANSMITTER
