Counter

A counter is a device for detecting ( and mostly ads ) of numbers and quantities. There are two basic types of pulse and Mengenzählwerke. A Pulse counter counts individual events such as mechanical shock movements ( Hand Tally ) or electrical impulses. A Mengenzählwerk one continuous variables such as the distance traveled on a vehicle ( shown as mileage).

Counting capacity

The count capacity, ie the total number c of possible indicator values ​​at all by the number of Zählwerkstypen cascaded counter stages and the number of digits in each counter stage as

Given.

Continue counting after reaching the peak level meter leads in the simplest case to the fact that the display again start at zero (so-called overflow). However, the meter can eg also be set up so that the display then stops at the highest level.

Designs

Counters are mechanical, electromechanical or electronic.

Mechanical counters

The oldest Zählwerktypen work mechanically. A Roller formerly called totalizer consists of multiple roles on one axis. The first role is a mechanism by a defined angle, usually 1/10 rotation, turned further and locks into the next position. Each role has in this case a single tooth on the end of a full revolution of the next roll of 1/ 10 of a turn is rotated. On the reels the numbers from 0 to 9 are plotted; the transfer takes place in this case, between the 9 and 0. The position of all roles will thus be directly read as a decimal number.

Mengenzählwerken at the counter is a defined angle, but not driven by each continuously via a transmission. As more digits are displayed, as are necessary for business transactions ( for example, required only for calibration purposes digits), they can be displayed instead of a digit role at a scale. In aufsummierender acquisition ( for example, volume measurement of a flow ) to the least significant digit frequently rotates continuously.

Electromechanical counters

Electromechanical counters are mechanical counters with an electric drive. Upon detection of individual events, an electrical pulse activates a solenoid or electric motor, which continues to rotate, the least significant digit roller. In aufsummierender acquisition ( for example, energy measurement of active power ) is continuously detected.

Electronic counters

Electronic decimal previously realized with Zählröhren. Today, they are built with integrated circuits (ICs ) in many varieties. You are always pulse counter, as they work digitally (see digital technology ). We distinguish synchronous or asynchronous counter circuits there. Among the features of these circuits is one of their storage capacity. The output signal is determined by the clock and the cached states of the counter.

The elementary building blocks of an electronic meter are edge-triggered flip-flops. State -controlled flip-flops ( latches ) are unsuitable. The individual digits are displayed in the binary system by the initial state of the flip-flops. The pulses are applied as a voltage signal to the clock input of the counter, whereby the state changes conversely from logic "0" to "1" or not. The transition from "1" to "0", a carry is triggered, the flip-flops changes the state of the next-higher.

The count capacity c of a binary counter is at n stages. Are skipped by additional measures k states so remain m counter states.

These four groups can be cascaded, depending on the design to a multi-digit binary or multi-digit decimal number. The latter is useful for immediate reading and processing by humans; a conversion of the binary number for the display can be dispensed with. We also speak of Dezimalzählern.

Softwarezählwerke

With the continuing shift of functions from special components in microprocessor-based systems counter works are more and more simulated by programs. Although computers also contain true digital counters, software counters can be simulated by a program, as it is listed here in pseudocode:

: = 0 start of loop    Wait Event    : = end of loop The variable is set at the beginning of the program to 0. The following instructions are repeated endlessly: The computer waits for the occurrence of the event to be counted. When the event occurs, the variable is incremented by one.

Applications

Counters are found in many everyday industrial applications. Classic examples of flow meters are odometer in vehicles. They were by the end of the 1980s, almost without exception, mechanically, but are now implemented electronically in almost all vehicle types. Also, water meter, heat meter, electric meter and gas meter are meter.

Pulse counter, for example, the charging unit counters to phones. Until the 1990s, the most separate electromechanical counters were. Today it is a software counters realized in the telecommunications equipment built-in function.