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Summary of Contents for senseca HD3910 Series
- Page 1 OPERATING MANUAL HD3910 series Soil volumetric water content (VWC) probes V1.0...
- Page 2 HD3910 series – Soil volumetric water content probes V1.0 Contents Introduction ..................... 3 Technical specifications ................4 Measuring principle .................. 5 Installation ....................6 4.1 Electrical connections ................7 Setting of RS485 Modbus-RTU parameters ..........9 Modbus-RTU protocol ................10 SDI-12 protocol ..................
- Page 3 HD3910 series – Soil volumetric water content probes V1.0 Introduction The probes HD3910.1 (two electrodes) and HD3910.2 (three electrodes) measure the soil volumetric water content (VWC) by using a capacitive measurement principle which allows fast measurements in the field and with minimal invasiveness.
- Page 4 HD3910 series – Soil volumetric water content probes V1.0 2 Technical specifications Volumetric water content Measuring principle Capacitive Measuring range 0…60% VWC Resolution 0.1% Accuracy (@ 23 °C) 3 % between 0 and 50% VWC (standard mineral soil, EC < 5 mS/cm) Measuring volume =100 mm x H=150 mm (HD3910.1…)
- Page 5 HD3910 series – Soil volumetric water content probes V1.0 3 Measuring principle The moist soil is composed of a solid part (minerals), a liquid part (generally water) and a gaseous part (air, water vapor). The Volumetric Water Content (VWC) is defined as the ratio between the volume occu-...
- Page 6 HD3910 series – Soil volumetric water content probes V1.0 4 Installation By means of an accessory, perform a hole into the soil deep enough to accommodate the probe. Never use the probe to make the hole in the soil, to avoid mechanical damage to the probe itself.
- Page 7 HD3910 series – Soil volumetric water content probes V1.0 4.1 Electrical connections Function Wire color RS485 output SDI-12 output Analog output (HD3910.x.x) (HD3910.xS.x) (HD3910.xAx.x) Black +Vdc +Vdc +Vdc White RS485 A/- DATA +Vout_W (%VWC) Green RS485 B/+ +Vout_T (Temperature) Connect the cable shield to the negative of power supply.
- Page 8 HD3910 series – Soil volumetric water content probes V1.0 Analog output connection (HD3910.xAx.x): Power supply Load resistance RL > 10 k. The Vout_W output corresponds to 0…60% VWC. The Vout_T output corresponds to -40…+60 °C. Page 8 of 16...
- Page 9 HD3910 series – Soil volumetric water content probes V1.0 5 Setting of RS485 Modbus-RTU parameters By default, the probe has Modbus address 1 and communication parameters 19200, 8E1. The address and the communication parameters can be changed as shown below.
- Page 10 HD3910 series – Soil volumetric water content probes V1.0 6 Modbus-RTU protocol The probe enters RS485 Modbus-RTU mode immediately after power on. Below is the list of registers. Input Registers: Address Description Format Status register 16-bit Integer Volumetric water content (VWC) in % [x10]...
- Page 11 HD3910 series – Soil volumetric water content probes V1.0 7 SDI-12 protocol The probes with SDI-12 output are compatible with 1.3 version of the protocol. The communication parameters of the protocol are “1200, 7E1”. By default, the SDI-12 address is 0 and can be changed by using the appropriate SDI- 12 command.
- Page 12 HD3910 series – Soil volumetric water content probes V1.0 Type M (start measurement) and type C (start concurrent measurement) com- mands Command Reply Description VWC and temperature atttn<CR><LF> Request to detect the measurements. where: a = probe address (1 character)
- Page 13 HD3910 series – Soil volumetric water content probes V1.0 Command Reply Description Signal level and temperature aM2! atttn<CR><LF> Request to detect the measurements. where: aC2! a = probe address (1 character) ttt = number of seconds needed by the probe to...
- Page 14 HD3910 series – Soil volumetric water content probes V1.0 Maintenance The probe does not require any special maintenance. We recommend a periodic cleaning with water and normal detergent of the electrodes in order to avoid the accumulation of substances that could alter the measurement.
- Page 15 WARRANTY The manufacturer is required to respond to the "factory warranty" only in those cases provided by Legislative Decree 6 September 2005 - n. 206. Each instrument is sold after rigorous inspections; if any manufacturing defect is found, it is necessary to contact the distributor where the instrument was purchased from.
- Page 16 Senseca Italy S.r.l. Via Marconi, 5 35030 Selvazzano Dentro (PD) ITALY info@senseca.com...
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