GHM DeltaOHM LPPYRA10 User manual

Operating manual
Pyranometer
LPPYRA10
www.deltaohm.com
English
Keep for future reference.

LPPYRA10 - 2 - V2.6
TABLE OF CONTENTS
1 INTRODUCTION .................................................................................................... 3
2 WORKING RINCI LE ........................................................................................... 4
3 INSTALLATION ..................................................................................................... 6
4 ELECTRICAL CONNECTIONS ................................................................................ 10
4.1 LPPYRA10 CONNECTIONS ................................................................................... 10
4.2 LPPYRA10AC[4] CONNECTIONS ........................................................................... 11
4.3 LPPYRA10AV[4] CONNECTIONS ........................................................................... 11
4.4 LPPYRA10S CONNECTIONS .................................................................................. 12
4.5 LPPYRA10S12 CONNECTIONS .............................................................................. 13
4.6 LPPYRA10ACS[4] CONNECTIONS ......................................................................... 14
5 MEASUREMENT IN THE MODELS WITH ANALOG OUT UT .................................... 15
5.1 LPPYRA10 ..................................................................................................... 15
5.2 LPPYRA10AC[S][4] ........................................................................................ 15
5.3 LPPYRA10AV[4] ............................................................................................. 15
6 RS485 MODBUS-RTU OUT UT ............................................................................. 16
6.1 SETTING THE COMMUNICATION PARAMETERS ............................................................... 16
6.2 READING THE MEASURES WITH THE MOD US-RTU PROTOCOL .......................................... 18
7 SDI-12 OUT UT .................................................................................................. 19
8 MAINTENANCE .................................................................................................... 23
9 TECHNICAL S ECIFICATIONS ............................................................................. 24
10 SAFETY INSTRUCTIONS ...................................................................................... 25
11 ACCESSORIES ORDERING CODES ....................................................................... 26

LPPYRA10 - 3 - V2.6
1 INTRODUCTION
LPPYRA10 pyranometer measures the irradiance on a flat surface (W/m2). The meas-
ured irradiance (Global Irradiance) is the sum of direct solar irradiance and diffuse ir-
radiance.
LPPYRA10 is a Spectrally Flat Class A (Secondary Standard) pyranometer in accord-
ance with ISO 9060:2018 and with the criteria of the WMO “Guide to Meteorological
Instruments and Methods of Observation”.
The pyranometer is available in the following versions:
•L YRA10: PASSIVE.
The passive version can be connected to the instruments
D09847 and HD31 by using VP 472 SICRAM module.
•L YRA10AC: ACTIVE with 4..20 mA CURRENT output (0…2000 W/m2).
•L YRA10AC4: ACTIVE with 4..20 mA CURRENT output (0…4000 W/m2).
•L YRA10ACS: ACTIVE with 4..20 mA CURRENT output (0…2000 W/m2) and
RS485 Modbus-RTU output.
•L YRA10ACS4: ACTIVE with 4..20 mA CURRENT output (0…4000 W/m2) and
RS485 Modbus-RTU output.
•L YRA10AV: ACTIVE with 0..1 or 0..5 or 0..10 V VOLTAGE output (0…2000
W/m2) to be defined when ordering.
•L YRA10AV4: ACTIVE with 0..1 or 0..5 or 0..10 V VOLTAGE output (0…4000
W/m2) to be defined when ordering.
•L YRA10S: With RS485 Modbus-RTU output.
•L YRA10S12: With SDI-12 output.
The pyranometer is supplied factory calibrated and with a calibration report. The cali-
bration is carried out in accordance with the ISO 9847:1992 (type IIc) standard: ”Cal-
ibration of field pyranometers by comparison to a reference pyranometer”. The pyra-
nometer is calibrated by comparison with the reference sample calibrated annually at
WRC (World Radiation Center).

LPPYRA10 - 4 - V2.6
2WORKING RINCI LE
LPPYRA10 pyranometer is based on a thermopile sensor. The thermopile sensitive sur-
face is coated with a black matt paint, which allows the pyranometer not to be selec-
tive at different wavelengths.
In order to grant the thermopile a proper thermal insulation from the wind and reduce
the sensitivity to thermal irradiance, LPPYRA10 is equipped with two concentric domes
having 50 mm and 32 mm outer diameter. The domes protect the thermopile from the
dust, which might change spectral sensitivity if it lies on the black surface,
The pyranometer spectral range is determined by the transmission of the two glass
domes. Thanks to the use of a new material for the manufacturing of the domes, the
spectral range has been further extended to short wavelengths starting from 283 nm.
Considering a standard solar spectrum, the portion of solar irradiation measured by
the pyranometer is greater than 99.8%. Figure 2.1 shows the relative spectral sensi-
tivity of the LPPYRA10 pyranometer and a standard solar spectrum.
Fig. 2.1: L YRA10 pyranometer relative spectral sensitivity (blue line) com-
pared with a standard solar spectrum (red line)
Radiant energy is absorbed by the thermopile black surface, thus creating a difference
of temperature between the center of the thermopile (hot junction) and the pyranom-
eter body (cold junction). Thanks to the Seebeck effect, the difference of temperature
between hot and cold junction is converted into a Difference of Potential.
A second thermopile, not accessible by light, is mounted inside the instrument. This
second thermopile, connected in anti-series with respect to the sensor exposed to
light, reduces the signals due to sudden temperature changes of the pyranometer
(thermal shocks).
In order to minimize sensitivity changes with temperature, LPPYRA10 is equipped with
a passive compensation circuit. The graph in figure 2.2 shows the typical variation of
sensitivity at different temperatures. The deviations are calculated from the sensitivity
measured at 20 °C.

LPPYRA10 - 5 - V2.6
Fig. 2.2: : percentage change of L YRA10 pyranometer sensitivity in the
temperature range -20…50 °C compared to the sensitivity at 20 °C
To prevent internal condensation forming on the internal side of the dome under cer-
tain climatic conditions, silica gel tablets are inserted inside the pyranometer to ab-
sorb humidity.
Fig. 2.3: scheme of principle L YRA10 (version with mV output)
T
h
ermopil
e
Surge
Protector
Connector pins
Housing
To cable shield
Temperature (°C)
% change of sensitivity
T
h
ermopil
e
Temperature
compensation

LPPYRA10 - 6 - V2.6
3INSTALLATION
efore installing the pyranometer, refill the cartridge containing silica-gel crystals. Sil-
ica gel absorbs humidity in the dome chamber and prevents, in particular climatic
conditions, condensation on the internal walls of the domes and measurement altera-
tion.
Do not touch the silica gel crystals with your hands while refilling the cartridge. Carry
out the following instructions in an environment as drier as possible:
1. Loosen the three screws that fix the white shade disk.
2. Unscrew the silica gel cartridge using a coin.
3. Remove the cartridge perforated cap.
4. Open the sachet containing silica gel (supplied with the pyranometer).
5. Fill the cartridge with the silica gel crystals.
6. Close the cartridge with its own cap, paying attention that the sealing O-ring be
properly positioned.
7. Screw the cartridge to the pyranometer body using a coin.
8. Check that the cartridge is screwed tightly (if not, silica gel life will be reduced).
9. Position the shade disk and screw it with the screws.
10. The pyranometer is ready for use.
The figure below shows the operations necessary to fill the cartridge with the silica gel
crystals.
Fig. 3.1: filling the silica-gel cartridge
Silica
-
gel
cartridge
Perforated cap
Sealed sachet
of silica-gel crystals
Filling Closing the cartridge

LPPYRA10 - 7 - V2.6
•The pyranometer must be mounted in an easy-to-reach location in order to clean
the dome regularly and carry out maintenance. At the same time, make sure that
no buildings, constructions, trees or obstructions exceed the horizontal plane where
the pyranometer lies. If this is not possible, select a site where obstructions in the
path of the sun from sunrise to sunset do not exceed 5 degrees of elevation. N.B.:
The presence of obstructions on the horizon line affects significantly the
measurement of direct irradiance.
•The pyranometer must be located far from any kind of obstruction, which might re-
flect sunlight (or sun shadow) onto the pyranometer itself.
•In compliance with ISO TR9901 standard and WMO recommendations, when the
pyranometer is used without the white shade disk, it must be positioned so that its
connector is pointed to the North Pole, if the instrument is used in the Northern
Hemisphere, and to the South Pole, if used in the Southern Hemisphere. In any
case, it is better to follow this suggestion even when the shade disk is applied.
•For fixing, use the holes on the pyranometer body (remove the shade disk to ac-
cess the holes and reposition it after mounting) or the suitable accessories (see the
figures below). In order to allow an accurate horizontal positioning, the pyranome-
ter is equipped with a levelling device: the adjustment is made by means of the two
levelling screws that allow adjusting the pyranometer inclination. The mast height
does not exceed the pyranometer plane to avoid measurement errors caused by
any reflection or shadow of the mast itself.
•It is preferably to thermally insulate the pyranometer from its mounting bracket
ensuring, at the same time, a good electrical contact to ground.
Fig. 3.2: fixing holes and levelling device
Fixing holes ∅ 6 mm
Levelling
device

LPPYRA10 - 8 - V2.6
HD2003.79K
HD2003.77C
HD2003.83
HD2003.83.1
HD2003.85K
D
HD9007
LPPYRA10
HD9007T29.1
C
A
B
TP32MTT.03.C
80° MAX
int.
M37 x 2
Fig. 3.3: fixing accessories
A = Palo 75 mm
B = Raccordo di base
C = Piastra di supporto graduata
D = Staffa per piranometro

LPPYRA10 - 9 - V2.6
Fig. 3.4: fixing accessories

LPPYRA10 - 10 - V2.6
4ELECTRICAL CONNECTIONS
L YRA10, L YRA10AC[4] and L YRA10AV[4] have a 4-pole connector and use
the C M12AA4... optional cables, with 4-pole connector on one side and open wires
on the other side.
L YRA10S and L YRA10S12 have a 8-pole connector and use the C M12-8D...
optional cables, with 8-pole connector on one side and open wires on the other side.
L YRA10ACS[4] has a 8-pole connector and uses the C M12-8DA... optional ca-
bles, with 8-pole connector on one side and open wires on the other side.
The metallic housing of the pyranometer should preferably be
grounded ( ) locally. In this case, do not connect the wire of the
cable corresponding to the housing to prevent ground loops.
Only if it is not possible to ground locally the metallic case of the
pyranometer, connect the wire of the cable corresponding to the
housing to ground ( ). Note: in LPPYRA10AV[4] the housing is not
connected to the connector.
Inside the housing there is a surge protector connected between the
housing itself and the electronic circuit (powered models) or the ca-
ble shield (passive model). Grounding the housing allows the correct
protection function (in particular against lightning) of the surge pro-
tector.
4.1 L YRA10 CONNECTIONS
The pyranometer LPPYRA10 is passive and does not require power supply. It is to be
connected either to a millivoltmeter or to a data acquisition system. Typically, the py-
ranometer output signal does not exceed 20 mV. In order to better exploit the pyra-
nometer features, the readout instrument should have 1 µV resolution.
Connector Function Color
1 +Vout Red
2 -Vout lue
3 Housing (C) White
4 Cable shield (SH) lack
12
34
+Vout
-Vout
SH
C
Fig. 4.1: L YRA10 connections
CPM12AA4… cable
Pyranometer M12
male connector
Datalogger or
converter/amplifier
with V or mA output
Connect to ground only if it is not possible to
ground locally the housing of the pyranometer
To circuit
Housing
Surge
protector

LPPYRA10 - 11 - V2.6
4.2 L YRA10AC[4] CONNECTIONS
The pyranometer LPPYRA10AC[4] has 4…20 mA output and requires 10…30 Vdc ex-
ternal power supply. It is to be connected to a power supply and an instrument with
4…20 mA input as shown in fig. 4.2. The load resistance of the instrument reading the
signal must be ≤ 500 Ω.
Connector Function Color
1 Positive (Iin) Red
2 Negative (Iout) lue
3 Housing (C) White
4 Cable shield (SH) lack
4...20 mA
12
34SH
Iin
Iout
C
Fig. 4.2: L YRA10AC[4] connections
4.3 L YRA10AV[4] CONNECTIONS
The pyranometer LPPYRA10AV[4] has 0…1 V, 0…5 V or 0…10 V output (depending
on the ordered output) and requires external power supply: 10…30 Vdc for 0…1 V
and 0…5 V outputs, 15…30 Vdc for 0…10 V output. It is to be connected to a power
supply and an instrument with voltage input as shown in fig. 4.3. The load resistance
of the instrument reading the signal must be ≥ 100 kΩ.
Connector Function Color
1 Output positive (+Vout) Red
2 Output negative
Power supply negative (GND) lue
3 Power supply positive (+Vdc) White
4 Cable shield (SH) lack
12
34
SH
GND
+Vdc
+Vout
Fig. 4.3: L YRA10AV[4] connections
CPM12AA4… cable
Pyranometer M12
male connector
Power supply
Connect to ground only if it is not possible to
ground locally the housing of the pyranometer
Instrument with
4…20 mA input
CPM12AA4… cable
Pyranometer M12
male connector
P
ower supply
Instrument
with
voltage input

LPPYRA10 - 12 - V2.6
4.4 L YRA10S CONNECTIONS
The pyranometer LPPYRA10S has RS485 Modbus-RTU output and requires
5…30 Vdc external power supply. It is to be connected to a power supply and to a
PLC, a data logger or a RS485/US or RS485/RS232 converter for PC as shown in fig.
4.4. The RS485 output is not isolated.
Connector Function Color
1 Power supply negative (GND) lue
2 Power supply positive (+Vdc) Red
3 Not connected
4 RS485 A/- rown
5 RS485 /+ White
6 Housing / Cable shield (SH) lack
7 Not connected
8 Not connected
ShieldShield
Lmax = 1200m
B/+
A/-
12
3
456
7
8
B/+
A/-
SGND
+Vdc
GND
GND
+Vdc
A/-
B/+
SH
R
220
T
Ω
R
220
T
Ω
Fig. 4.4: L YRA10S connections
efore connecting the pyranometer to the RS485 network, set the address and the
communication parameters, if different from the factory preset (see chapter 6).
Power supply
CPM12-8D… cable
Pyranometer M12
male connector
PLC, data logger or
RS485/US or
RS485/RS232
converter for PC
Other sensors with
RS485 output
Connect to ground only if it is not possible to
ground locally the housing of the pyranometer

LPPYRA10 - 13 - V2.6
4.5 L YRA10S12 CONNECTIONS
The pyranometer LPPYRA10S12 has SDI-12 output and requires 7…30 Vdc external
power supply. It is to be connected to a power supply and to an acquisition system
(data logger) as shown in fig. 4.5.
Connector Function Cable color
1 Power supply negative (GND)
SDI-12 output negative lue
2 Power supply positive (+Vdc) Red
3 Not connected
4 Not connected
5 SDI-12 output positive White
6 Housing / Cable shield (SH) lack
7 Not connected
8 Not connected
DATA
GND
12
3
456
7
8GND
+Vdc
SDI-12
SDI-12 BUS
+
-
+Vdc
GND
SH
Fig. 4.5: L YRA10S12 connections
More SDI-12 sensors can be connected in parallel. The distance between a sensor and
the acquisition system (data logger) should not exceed 60 m.
Due to its low power consumption (< 200 µA), LPPYRA10S12 is particularly suitable
for battery/solar panel-powered data acquisition systems.
efore connecting the instrument to an SDI-12 network containing other sensors, set
the address by using the proper SDI-12 command (see chapter 7).
Data logger
input
Pyranometer M12
male connector CPM12-8D… cable
Power supply
Other SDI-12
sensor
Other SDI-12
sensor
Connect to ground only if it is not possible to
ground locally the housing of the pyranometer

LPPYRA10 - 14 - V2.6
4.6 L YRA10ACS[4] CONNECTIONS
The pyranometer LPPYRA10ACS[4] has two outputs:
•One 4…20 mA output, requiring 10…30 Vdc external power supply. It is to be
connected to a power supply and an instrument with 4…20 mA input as shown in
fig. 4.6. The load resistance of the instrument reading the signal must be ≤ 500 Ω.
•One RS485 Modbus-RTU output, requiring 5…30 Vdc external power supply.
It is to be connected to a power supply and to a PLC, a data logger or a
RS485/US or RS485/RS232 converter for PC as shown in fig. 4.6. The RS485
output is not isolated.
Connector Function Color
1 Power supply negative (GND) lue
2 Power supply positive (+Vdc) Red
3 Digital and analog ground
(SGND) lack
4 RS485 A/- rown
5 RS485 /+ White
6 Housing / Cable shield (SH) lack (thick wire)
7 Analog output positive (AOUT) Green
8 Not connected
R
220
T
ΩShieldShield
Lmax = 1200m
B/+
A/-
12
3
456
7
8
B/+
A/-
SGND
+Vdc
GND
4...20 mA
AOUT
SGND
GND
+Vdc
A/-
B/+
SH
R
220
T
Ω
Fig. 4.6: L YRA10ACS[4] connections
efore connecting the pyranometer to the RS485 network, set the address and the
communication parameters, if different from the factory preset (see chapter 6).
Power supply
CPM12-8DA… cable
Pyranometer M12
male connector
PLC, data logger or
RS485/US or
RS485/RS232
converter for PC
Other sensors with
RS485 output
Connect to ground only if it is not possible to
ground locally the housing of the pyranometer

LPPYRA10 - 15 - V2.6
5MEASUREMENT IN THE MODELS WITH ANALOG OUT UT
elow are the ways to calculate the global irradiance in the models with analog output
LPPYRA10, LPPYRA10AC[S][4] and LPPYRA10AV[4].
5.1 L YRA10
Each pyranometer is distinguished by its own sensitivity (or calibration factor) S ex-
pressed in µV/(Wm-2) and shown in the label on the pyranometer (and in the calibra-
tion report).
The irradiance Ee is obtained by measuring with a multimeter the difference of potential
DDP at the ends of the sensor and applying the following formula:
Ee = DDP / S
where:
Ee is the irradiance expressed in W/m2;
DDP is the difference of potential expressed in µV measured by the multimeter;
S is the sensitivity of the pyranometer expressed in µV/(Wm-2).
5.2 L YRA10AC[S][4]
The 4…20 mA output signal corresponds to 0…2000 W/m2 (LPPYRA10AC[S]) or 0…4000
W/m2 (LPPYRA10AC[S]4) irradiance range.
The irradiance Ee is obtained by measuring with a multimeter the current Iout absorbed
by the sensor and applying the following formula:
Ee = 125 • (Iout - 4) if f.s.= 2000 W/m2
Ee = 250 • (Iout - 4) if f.s.= 4000 W/m2
where:
Ee is the irradiance expressed in W/m2;
Iout is the current expressed in mA absorbed by the pyranometer.
5.3 L YRA10AV[4]
The output signal (0…1 V, 0…5 V or 0…10 V depending on the version) corresponds to
0…2000 W/m2 (LPPYRA10AV) or 0…4000 W/m2 (LPPYRA10AV4) irradiance range.
The irradiance Ee is obtained by measuring with a multimeter the output voltage Vout of
the sensor and applying the following formula:
Ee = 2000 • Vout for the version 0…1 V with f.s.= 2000 W/m2
Ee = 4000 • Vout for the version 0…1 V with f.s.= 4000 W/m2
Ee = 400 • Vout for the version 0…5 V with f.s.= 2000 W/m2
Ee = 800 • Vout for the version 0…5 V with f.s.= 4000 W/m2
Ee = 200 • Vout for the version 0…10 V with f.s.= 2000 W/m2
Ee = 400 • Vout for the version 0…10 V with f.s.= 4000 W/m2
where:
Ee is the irradiance expressed in W/m2;
Vout is the output voltage expressed in V measured by the multimeter.

LPPYRA10 - 16 - V2.6
6RS485 MODBUS-RTU OUT UT
efore connecting the pyranometer to the RS485 network, an address must be assigned
and the communication parameters must be set, if different from the factory preset.
6.1 SETTING THE COMMUNICATION ARAMETERS
Connect the pyranometer to the PC in one of the following two ways:
A. y using the optional C 24 cable, with built-in RS485/US converter. In this con-
nection mode, the sensor is powered by the PC US port. To use the cable, it is
necessary to install the related US drivers in the PC.
B. y using the supplied 8-pole M12 female connector or the optional C M12-8D…
cable and a generic RS485/US or RS485/RS232 converter. In this connection
mode, it is necessary to power the pyranometer separately. If a RS485/US con-
verter is used, it is necessary to install the related US drivers in the PC.
NOTES ON THE INSTALLATION OF UNSIGNED USB DRIVER: before installing unsigned US driver into
operating systems starting from Windows 7, it is necessary to restart the PC by disabling the
driver signing request. If the operating system is 64-bit, even after installation the request of
driver signing have to be disabled each time the PC is restarted.
rocedure:
1. Start with the pyranometer not powered (if the CP24 cable is used, disconnect one
end of the cable).
2. In the PC, start a serial communication program. Set the aud Rate to 57600 and
set the communication parameters as follows (the pyranometer is connected to a
COM type port):
Data its: 8
Parity: None
Stop its: 2
In the program, set the COM port number to which the pyranometer will be con-
nected.
3. Switch the pyranometer on (if the CP24 cable is used, connect both ends of the
cable).
Power supply
or
CPM12-8D… cable Red
lue
rown
White
Pyranometer
connector
CP24 cable
Pyranometer
connector

LPPYRA10 - 17 - V2.6
4. Within 10 seconds from the pyranometer power on, send the @ command and
press Enter.
Note: if the pyranometer does not receive the @ command within 10 seconds from
power on, the RS485 MOD US mode is automatically activated. In such a case, it is
necessary to switch off and on again the pyranometer.
5. Send the command CAL USER ON.
Note: the command CAL USER ON is disabled after 5 minutes of inactivity.
6. Send the serial commands given in the following table to set the RS485 MOD US
parameters:
Command Response Description
CMAnnn &| Set RS485 address to nnn
Ranging from 1 to 247
Preset on 1
CM n &| Set RS485 aud Rate
n=0  9600 n=1  19200 n=2  38400
n=3  57600 n=4  115200
Preset on 1  19200
CMPn &| Set RS485 transmission mode
n=0  8-N-1 (8 data bits, no parity, 1 stop bit)
n=1  8-N-2 (8 data bits, no parity, 2 stop bits)
n=2  8-E-1 (8 data bits, even parity, 1 stop bit)
n=3  8-E-2 (8 data bits, even parity, 2 stop bits)
n=4  8-O-1 (8 data bits, odd parity, 1 stop bit)
n=5  8-O-2 (8 data bits, odd parity, 2 stop bits)
Preset on 2  8-E-1
CMWn &| Set receiving mode after RS485 transmission
n=0  Violate protocol and go in Rx mode right after Tx
n=1  Respect protocol and wait 3.5 characters after Tx
Preset on 1  Respect the protocol
7. You can check the parameters setting by sending the following serial commands:
Command Response Description
RMA Address Read RS485 address
RM Baud Rate
(0,1)
Read RS485 aud Rate
0  9600 1  19200 2  38400
3  57600 4  115200
RMP Tx Mode
(0,1,2,3,4,5)
Read RS485 transmission mode
0  8-N-1
1  8-N-2
2  8-E-1
3  8-E-2
4  8-O-1
5  8-O-2
RMW Rx Mode
(0,1)
Read receiving mode after RS485 transmission
0  Violate protocol and go in Rx mode right after Tx
1  Respect protocol and wait 3.5 characters after Tx
Note: it is not required to send the CAL USER ON command to read the settings.

LPPYRA10 - 18 - V2.6
6.2 READING THE MEASURES WITH THE MODBUS-RTU ROTOCOL
In MOD US mode, you can read the values measured by the pyranometer through
the function code 04h (Read Input Registers). The following table lists the quantities
available with the appropriate register address:
Number Address Quantity Format
1 0 Internal temperature in °C (x10) 16-bit Integer
2 1 Internal temperature in °F (x10) 16-bit Integer
3 2 Solar radiation in W/m2 16-bit Integer
4 3 Status register:
bit0=1  solar radiation measurement error
bit2=1  configuration data error
bit3=1  program memory error
16-bit Integer
5 4 Average values of the last 4 measurements 16-bit Integer
6 5 Signal generated by the sensor in µV/10
[e.g.: 816 means 8160 µV, the resolution is 10 µV]
16-bit Integer
Note: Register address = Register number - 1, as defined in the Modbus standard.
OERATING MODE: the pyranometer enters RS485 MOD US-RTU mode after 10 sec-
onds from power on. In the first 10 seconds from power on the pyranometer does not
reply to requests from the MOD US master unit. After 10 seconds, it is possible to
send MOD US requests to the pyranometer.

LPPYRA10 - 19 - V2.6
7SDI-12 OUT UT
The LPPYRA10S12 pyranometers are compatible with version 1.3 of SDI-12 protocol.
The protocol communication parameters are: aud rate = 1200. Data bits = 7, Parity
= Even, Stop bits = 1.
The communication with the instrument is performed by sending a command in the
following form:
<Address><Command>!
with <Address> = address of the instrument the command is sent to
<Command> = type of operation requested to the instrument
The instrument reply is as follows:
<Address><Data><CR><LF>
with <Address> = address of the instrument which replies
<Data> = information sent by the instrument
<CR> = ASCII character Carriage Return
<LF> = ASCII character Line Feed
The sensors come with a factory address preset to 0. The address can be modified by
using the proper SDI-12 command reported in the following table.
The following table reports the SDI-12 commands available. For consistency with SDI-
12 standard documentation, the instrument address is indicated in the table with the
letter a.
SDI-12 Commands
Command Instrument reply Description
a! a<CR><LF> Verifies the presence of the
instrument.
aI! allccccccccmmmmmmvvvssssssss<CR><LF>
with:
a = address of the instrument (1 character)
ll = SDI-12 compliant version (2 characters)
cccccccc = manufacturer (8 characters)
mmmmmm = instrument model (6 characters)
vvv = firmware version (3 characters)
ssssssss = serial number (8 characters)
 Example of response:
013DeltaOhmLP-PYRA0016051518
with:
0 = instrument address
13 = SDI-12 version 1.3 compliant
DeltaOhm = manufacturer’s name
LP-PYR = instrument model
A00 = firmware version A.0.0
16051518 = serial number
Requests for information
from the instrument.
aAb!
Where:
b = new
address
b<CR><LF>
Note: if the b character is not an acceptable ad-
dress, the instrument responds with a instead of b.
Modification of the instru-
ment address.

LPPYRA10 - 20 - V2.6
Command Instrument reply Description
?! a<CR><LF> Request of the address of
the instrument. If more than
one sensor is connected to
the bus, a conflict occurs.
TY E M (START MEASUREMENT) AND TY E C (START CONCURRENT MEASUREMENT) COMMANDS
Irradiance, signal internal level and internal temperature
aM!
aC!
atttn<CR><LF>
with: ttt = number of seconds necessary for the in-
strument to make the measure available
(3 characters)
n = number of detected variables (1 character
for aM!, 2 characters for aC!)
Note: ttt = 000 means datum immediately available.
Request to execute the
measurement.
aD0! a+n+w…w+v…v+t…t<CR><LF>
with:
n = content of the status register
w…w = irradiance in W/m2
v…v = signal internal level in mV
t…t = internal temperature in the set unit of
measurement (default °C)
 Example of response: 0+0+228.7+3.294+25.0
probe address = 0
content of the status register = 0
irradiance = 228.7 W/m2
signal internal level = 3.294 mV
internal temperature = 25.0 °C
Note: the status register normally contains zero; a
value different from zero indicates an error condi-
tion.
Reads the measurement.
Irradiance and internal temperature
aM1!
aC1!
atttn<CR><LF>
with: ttt = number of seconds necessary for the in-
strument to make the measure available
(3 characters)
n = number of detected variables (1 character
for aM1!, 2 characters for aC1!)
Note: ttt = 000 means datum immediately available.
Request to execute the
measurement.
aD0! a+w…w+t…t<CR><LF>
with:
w…w = irradiance in W/m2
t…t = internal temperature in the set unit of
measurement (default °C)
 Example of response: 0+228.7+25.0
probe address = 0
irradiance = 228.7 W/m2
internal temperature = 25.0 °C
Reads the measurement.