SMKB-SPHS Soil PH Sensor
SMKB-SPHS soil PH sensor is developed by using solid AgCl reference electrode and high pure metal PH sensitive electrode, which has the characteristics of high measurement accuracy and long-term stability of signal, and can replace glass electrode. In addition, the isolation circuit design is adopted, which is suitable to be buried in the soil for long time online measurement. The PH sensor has temperature compensation inside, which can realize the numerical stability of PH within a certain temperature range. W ith the multi-directional function of power line, ground line and signal line, can prevent the damage caused by reverse connection, wrong connection and so on. Application: It is suitable for scientific experiment, water-saving irrigation, greenhouse, flowers and vegetables, grassland and pasture, soil rapid measurement, plant culture, sewage treatment, grain storage and measurement of water content and temperature of various particles.
Technical Parameters
| Measuring Range |
3 ~ 10 |
| Output Signal |
RS 485 / RS 232 / UART , MODBUS - RTU - PROTOCOL |
| Accuracy |
<0.25 |
| Repetition Error |
<0.2 |
| Temperature compensation Range |
0 - 5 Deg C |
| Power Supply |
5 ~ 24V (Max 26.7V) |
| Quiescent Current |
Measuring Peak<50mA, Average<2mA |
| Response Time |
2 ~ 15S (Adaptation) |
| Stabilized Time |
30m ~ 24hrs |
| Ingress Protection |
IP68 |
| Working Temperature |
-10 C ~ 70 C |
| Cable Length |
3.5m (Standard);Other For Optional |
Modbus Protocols
The function code is the content of the second byte sent by the host, in which the 03 and 04 function codes are to read the register value ; 06 function code is to write a single register ; 16 function code is to write multiple registers ; The 17 function code reads the device ID . No response to other function codes.
Communication Specification Setting
The RS-485 interface is a physical interface. The communication lines are generally bus-type. All communication stations are connected to the 485 bus. The communication protocol uses MODBUSRTU protocol, which is a master-slave protocol. There is a master station and multiple slave stations on a bus, and the communication parameters between each station must be consistent, including baud rate, data number , check bit and stop bit. The station address of each slave station must be different, otherwise a slave station response conflict will happen.
[1.] The SET terminal of the sensor is connected to the high level. The sensor is in SET mode, allowing modification of the internal EEPROM. At this time, the communication parameters displayed by the sensor are fixed as follows: station address 255,9600, n, 8,1.Y ou can set the parameters to the sensor and modify the 0x200-0x204, 0X209, and 0X20A registers.
[2.] The SET terminal of the sensor is connected to the low level, and the sensor is in the acquisition mode. At this time, the communication parameters SET inside the sensor will come into effect, that is, the communication will run according to the parameter definition of 0x200-0x204.
NOTE: In acquisition mode, internal parameters cannot be modified, even if the sensor responds to the write command
Attention
[1]PH sensitive electrode metal is very fragile, low strength, to avoi d stress and Impact. After being buried in the soil for a long time (3 months to half a year), the electrode should be cleaned and polished with high-grade sandpaper , or cleaned and soaked with 5% hydrochloric acid for a few minutes to make the metal electrode in bright silver color as new , and then washed with pure water .
[2] The non-metallic probe of the reference electrode is relatively thin w ith low strength, and stress and impact should also be avoided.
[3] The reference electrode should be kept moist when not in use.
[4]Neither electrode should touch the oily substance to avoid the electrical circuit barrier caused by the oil film covering
[5] The protection level of the sensor is IP68, the sensor can be whol ly soaked in water .
