【 Weak current College 】 how to select prepayment meter

I. currently, prepayment meter in the residential area of use is also increasing, mainly in the IC card meter, TM card meter, RF card meter and meter code. The four different water meters respectively.
1, IC card meter belongs to the first generation of prepayment meter, mainly using IC card as the main media, IC card is divided into logical cryptographic cards and store cards, logical cryptographic cards with Siemens 44 ¡á ¡á series card, ATMEL's 16 ¡á ¡á series cards; and storage cards mostly ATMEL's 24 ¡á ¡á series cards or 93C46 card, etc. Their difference is no memory card encryption performance, this requires that the amount of money, first by cryptographic algorithms into ciphertext, and then read into a meter by meter in SCM software and then decrypt the encryption using dynamic encryption, use once is updated, even if someone had a struggling to decode, or the password is used, so confidential performance is extremely high.　　But logic encryption card storage for all data must be password check, only when the password is correct, the party can read the data, the password is fixed, once deciphered or diarrhea, often larger losses, so the less dynamic encryption of storage card. The advantages of IC card meter is cheap, but people in the use process, found that the following issues: first, because the card, so the meter must be reserved for a read-write, which allows the body's internal electronic part is not completely closed, the meter must be combined with a protective cover, not the card when the lid is good, since most of the meter is placed in the damp kitchen and other places, such as improper mold design so that the lid is not strict, moisture easily immersed, causing corrosion metered internal lines, damaged water and moisture will enable the internal lithium battery discharge speed that most marked the life of more than 6 years of IC card meter in one to two years cannot be used. Worse is that some of the technical level of the manufacturers, the introduction of only 200 million of IC card table, completely without regard to electromagnetic compatibility and anti-interference measures of protection, as long as a circuit board into the IC card read-write, with a gas lighter, alignment of the plate of discharge, water meter immediately paralysis, a user can never enter amount and valve according to the white water. For these reasons, many have used IC card meter of pipe or water company are devoured, IC card meter has a large number of poor sales, the market maintains rate cannot be equated with remote meter reading.
2. code meter as the IC card meter like defects, code on the meter will produce, it does not have a IC card read-write, and instead is a keyboard, prepaid amount calculated by a computer algorithm for encryption, with a password to gain access to the password purchase water, followed by the keyboard to enter the password, a meter inside a single chip for decryption, resulting amount, it overcomes the IC card meter cannot be closed defects, from this point of view is an improvement, but at the same time it again higher than IC card meter back a step, IC card meter storage features, you can use the meter, if the total amount of water, whether electromagnetic interference, battery charge, has written to the card, such as an add-in, in the acquisition of water when the IC card information incoming Center computer so administrators can instantly understand and unlock the failure, but code meter without this feature, if the consumer when the batteries will do cause unexpected cuts off the ignorant, and the interim notice maintenance personnel door, this will cause great inconvenience to the user of water management center was stolen. So take a step further and decided to code the meter was destined to the fate of a large number of promotion.
3, TM card meter that is a new generation of prepayment meter, TM card uses United States DALLAS IBUTTON devices of the company, its appearance by stainless steel packaging, like a small battery, it is only a 2-wire transfer, a ground wire, one is the power and signal line, the comparison of IC card of 4-6 root line simple a lot, it can be completely closed, only water meters in the water, there is a similar pack battery box is used to read and write to the card, so the above shortcomings can be overcome on, it's another advantage is that multiple encryption TM card and a card number, data protection over logical cryptographic cards, also due to the stainless steel packaging, high and low temperature resistance extremely harsh conditions. TM card water form from its structure and electrical schematic, it inherently superior than IC card, water meter. But the disadvantage is the price a little high meters IC card, usually in the $ 400 or so, especially in the card itself, an IC card costs only dollars but TM card is 20 to 30 yuan.
4. RF card meter TM card is 2 generation of prepayment meter, and RF card meter belongs to the 3rd generation prepayment meter, TM card meter only physically settled water meter closed, but still can't complete electrical solutions, RF card meter, it is precisely this point, the so-called RF card, is a non-contact IC card, read-write card are transmitted by radio-frequency electromagnetic waves, which are completely blocked criminals take advantage of high-tech means to attack the vulnerability of water meters. RF card meter currently has only a few technology development strength strong companies to develop, the disadvantage is that the RF module and RF card costs are relatively high, and low power consumption, lithium battery life, you must replace the external battery, frequently, generally in more than $ 500, which temporarily affect its popularity.
II. Overview of pre-paid water meters in the status and development trend, the current cost-effective water meter for TM card, IC card meter as affordable, currently available at most, but not to confuse you, the consumer never cheap, be sure to select the technical strength of the manufacturers product. But the prepayment meter of read-write only on the card of choice is a connection, and error correction and anti-theft feature even more important. Pre-paid water meters in use recurring issues include the following scenarios, you can test that the pros and cons of prepaid water meters:
1, exception turn-off: in the Shui fee has not been exhausted, the water valve turn-off, causing user inconvenience.　　Such as high-rise towers, if water mains booster, high frequency, very easy to resonance lead valve turn-off, which mainly reflected in certain valves for solenoid valve and poor quality water meter. 2. electromagnetic interference: will a magnet near the water, which makes the water meter signal cannot output, resulting inNo billing or fewer billing, if water meter valve turn-off, indicate anti-electromagnetic interference, but how to deal with EMI after the valve to re-open issue and a water meter performance standards of good and bad. 3, battery life: many manufacturers nominal built-in lithium battery life is greater than six years, the actual use is less than two years, some manufacturers several months that drain the battery, a large section of meter using the ball valve, tube impurities affect ball valve on or off, and software design does not have smart judgment function, results in a constant process of driven valve battery drain.　　There must be recognition meter electricity detection alarm function, and how to deal with, if the low battery without any processing, the amount of exhaustion and the battery does not have enough power to close the valve, will allow users to freely use of water, water company and property management Department of the losses, if early closing valve and let users very inconvenient, which also is the evaluation standards. 4, Deb turn-off: consumer home water will do is unaware, or had not instant recharge, causing a sudden shut off during use, how to deal with is the evaluation standards.
The only listed above is currently prepayment meter use encounter some problems, in considering how to block a user illegally stolen water situations but lets the user create inconvenience, this is precisely the hamper prepayment meter extension. Just imagine, if a person is in the bath water, suddenly appear broken, desperation must call to service personnel on-site treatment before they open the water valve, its not convenience. At present, many manufacturers, on how to block a user illegally stolen water consider very much, once off the water, the user is unable to resolve by itself, you must unlock the door by service personnel, design of this product, without considering the humane. While the company launched the IC card meter and TM card meter, collective apartments with RF card meter, no more disadvantages. As you scan, exception occurs, the landlord can the card in a water meter, water meter user-friendly software designed to enable users to handle failures, and all fault information record card, unless the user information has been read; otherwise, the central computer limited three times and you can set arbitrary arrangement of overdraft amount will completely block valve, which completely blocked illegally stolen water vulnerability, and convenient to the users.