【 Weak current College 】 water, electricity and gas meters remote circuit and interface technology---Power By 【 China power house network 】

Residential community of intelligence, networking has become a residential construction development direction, which as a subsystem of three tables barbed was referred to the more prominent, and first to get the development. In the course of the development, because people are too attached importance to the advancement of the computer system, ignoring the sensor and interface circuits for reliability, resulting in many systems are computer system is running properly, but lost the role of collecting data accurately. The author has carefully studied the many applications of three table system on site, including some of the scene in which failure of the various sensors and interface circuits, in this introduction to everyone, hope as a reference.

1. water, electricity and gas from remote sensing of three table type
Water, electricity, gas quantity conversion to electrical signals, is a crucial and complex process, practice has shown that in the three tables barbed throughout the system, it is not like computer system that only determines the system of grades and standards, but to determine the success or failure of the entire system, experienced system technicians on this. Therefore, it is necessary specifically to remote analysis and research on three tables, in order to achieve better results.
At present, remote third table is basically a base table in the original mechanical retrofitting sensing circuit formation. This idea appears in the "make do", but is actually a very scientific design ideas.
1. the three base tables in the course of the entire international application, has reached a very mature, precision, reliability, unmatched. 2. the ability to easily without prejudice based on performance with transmitter circuit.
3. after the installation of remote transmission circuit is equipped with mechanical and remote transmission of two shows, and show a consistency of conditions (this point is very important).
Following on the transmitter circuits are explained:
1. photoelectric conversion-this sensor form generally is in the base table of rotating parts on one side retro-reflector, and mirror face corresponding parts of the fixed installation a photoelectric sensor, when rotating part mirror go to sensor position sensor produces optical sensing, issued a pulse signal.
The sensor form has three weaknesses: the ⑴ sensor itself to power, is not conducive to back-up battery power consumption of micro. ⑵ reflection surface contamination after reflection malfunctioning. fade ⑶ on the edge of the reflecting surface produces error signals. quiver ⑷ at least 4 of the leader.
If there is no good way to solve the above at all four issues, which means hope resolutely not use.
2. Hall sensor type
In the base table rotation parts equipped with induction Alnico magnet, and induction of its location on the fixed installation in a Hall element.
3. do a Reed pipe sensor type
Is the application up to a form, its biggest advantage that you do not have to power consumption. However there are induction point fibrillation false signal and external magnetic interference issues, plus a steering alarm Reed pipe will not solve the problem without a signal, and often throw "is a false alarm system is unreliable, or magnetic interference stealing water" disputes. This sensor is in the current application up, but the from field use, is also the most problems.
4. from the maintain switched
With A, B two inductive head, A head induction switch opens, switch has been open. Until B head go to only closed after the switch, and then transferred to A head, as the cycle again opened.
This form successfully overcame the fibrillation, magnetic interference, power consumption, leader of all shortcomings, only two lines enables signal and signal off, break, short four-State inspection, is the most ideal remote sensing methods.

Second, water, electricity, gas remote third table of interface technology
At present, the meter reading system acquisition unit interface: analog acquisition, switch data acquisition, pulse volume collection.
1. analog acquisition circuits
This acquisition technology as shown in the figure, has the following advantages:
(1) only two leads away signal driving, signal off, break, short four-State detection, meets all of the features.
(2) only the base occupies only one acquisition channel.
(3) interface of electromagnetic compatibility is significantly improved.
(4) at the same time can determine the power supply and backup battery condition.
The disadvantage of this circuit is data processing and analysis to a slightly more complex, and is only suitable for itself has steering function remote water meter, gas table.
For without steering features of sensing circuit (shown in figure A and figure B), the need to increase the Steering Reed pipe produces magnetic interference warning, in this case, data processing and analysis more complicated, and figure B circuit cannot distinguish between short or magnetic interference.
2. switch off the circuit of the acquisition of a major acquisition interface circuit are the following:
3. Pulse volume acquisition circuits
　
Three, two, for reference by sense acquisition circuits
The above lists the current multiple sensing acquisition circuits, because the "self", the scene has been installed on the remote table and is equipped with three computer acquisition system difficult to match, causing many site already installed in the three tables are removed, the whole project brings a lot of trouble. In addition, there are so many types of circuit, not only taking system technicians to be able to match this flip-flop, also let the user be dazzled, unable to look OK.
The author concluded a number of circuits, raised two worth recommending, is currently used by most sensor acquisition circuits, want to be able to help.
The first is that we previously mentioned analog acquisition circuits, as mentioned earlier, the advantage of this circuit is obvious, the sensor circuit is also a broader application of circuit.
The second is the earlier switch signal acquisition circuits (A), if K is disconnected, the signal for the Vc close when the K, the signal is 0, the usual alarm signal is 0, when the lead cut to Vc, circuit R 100 Ω or so current limiting resistors, R1, R2 for 10K-100K of pull-up resistor.