Description

Digital counters are electronic devices that perform a variety of counting functions. They may count single actions, provide totalizing, or perform other calculations. In addition to the number and type of functions, these electronic devices differ in terms of count direction and reset functions. Inputs and outputs, user interface, physical specifications, and available features are also important to consider.

Types

The GlobalSpec SpecSearch Database contains information and searchable data on the various functional types of digital counters.

• Frequency counters are units for displaying frequency, the number of cycles per second of a waveform. The unit of frequency is Hertz (Hz).
• Position indicators can accept, process, and display data involving traveling or display.
• Arithmetic functions can be programmed to a counter or timer. Some of these include the sum, difference, multiple, square root, etc.
• Controllers have outputs to regulate or control equipment based on sensor inputs or preset limits.
• Batch counters count UP only and are usually pre-settable so that when the required number of batches or pieces has been completed, the process can stop automatically.
• Count totalizers can accumulate counts but most cannot control a machine. Some totalizers are pre-settable, but their primary function is to keep track of counts over a relatively long period of time.
• Preset counters can control an external circuit when its counted total matches user-entered preset limits. Electronic models are the most versatile and offer high performance at a relatively low price. Mechanical and electrical types offer simplicity of installation and operation.  Preset mode is a counting mode where counting is generally subtractive. The counter resets or auto-recycles to the preset count. When the counter counts to zero, the output associated with the preset number occurs.
• Pulse counters are used to count a momentary but sharp change in current and voltage. Count pulses include square waves and rectangular waves. Pulses are digital signals; the voltage or current is either "on" or "off”.
• Counter and timer combinations are counters that can perform both counting and timing functions.

Specifications

A number of other specifications for digital timers should be considered other than or in addition to the desired functional type. These include counting direction, signal input type, and specialized inputs.

Counting Direction

Digital counters can count either up, down, or both up and down in sequence. Up counters advanced forward, such as from 1 to 2. Down counters move backward, such as from 2 to 1.  Bi-directional counters can count forward or backward in sequence, depending on an application’s requirements.

Signal Input

Digital counters can have voltage, current, frequency, or charge signal type. Voltage inputs are usually simple functions of the measurement. Current inputs are transmitter inputs. Frequency inputs are accepted from any device outputting a frequency signal or pulse train. Piezoelectric devices input charge signals which require filtering and amplification.

Specialized Inputs

Specialized inputs are custom inputs for more specialized applications than the conventional signal inputs mentioned previous. These include signals for digital logic, encoders, flow sensors, level sensors, mechanical switches, solid-state switches, and temperature sensors.