DDM, RDO, ZS confirm that there is no problem.  PH, NHN, ORP plasma selective sensors will slowly exude the reference solution, so try not to do this.  If you must test, after laboratory analysis, there is no problem, the exudation of ions are trace, does not affect health.  

The difference between RTU and DTU is the same. DTU is a single and simple wireless transmission function, while RTU is a wireless acquisition and transmission equipment integrating multi-channel analog data acquisition and switching data control.  It can be understood that RTU has acquisition function and can send acquisition instructions to sensors.  DTU is only responsible for transmission, not active data collection.  

At present, there are two kinds: the first kind is through the computer, PLC, EXO-202 and so on in the way of wiring to send data query instructions to the sensor, sensor response data through cable transmission to the computer, PLC, EXO-202, the response data can be converted into the test data, the computer needs software is serial debugging assistant.  The second method is to realize wireless transmission through DTU and RTU. DTU generally requires the cooperation of front-end devices. For example, DT-200 is responsible for data collection and DTU is responsible for data transmission, while RTU can realize both collection and transmission functions.  If we want to find the data from the server, we need the corresponding computer software and mobile phone software, or we can send the data to the client server, and the client can write the software to realize the data query.  

The data can be uploaded to the client server for validation.  The DT-200 collects the data from the connected sensor and sends the data to the DTU. The DTU then sends the parsed data to the server.  The data is uploaded to the server in the following format:  

1devid:10000,ecm:1455.4,tmp:24,5,rdo:10.36,tmp:15.3,ecs:281.9,tmp:24.4,phg:3.4,tmp:28.7,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,nul:0,tmp:0,end

The integrated sensor normally does not have a problem with the RS-485 protocol somewhere. The address of a single sensor on the integrated device is fixed and not the same. Even if a communication exception is caused by a failure, the whole device will not be affected.  
 
If the customer integrates, the above problems may be caused by the same address of multiple sensors.  If the communication protocol is abnormal, power-on will not communicate.  The default data formats for RS-485 communication are 9600, N, 8, and 1 (baud rate 9600 BPS, 1 start bit, 8 data bits, no check, and 1 stop bit).