Relay boards are computer boards with an array of relays and switches. They have input and output terminals and are designed to control the voltage supply. Relay boards provide independently programmable, real-time control for each of several onboard relay channels.
Product specifications include the number of channels, physical dimensions, input range, and output range. Relay boards with opto-isolators provide isolation between control signals and output controls. Software-based tools can be used to write batch files, and light emitting diodes (LEDs) provide are used as visual indicators. Most relay boards have 2, 4, 8 or 10 channels. Each channel has a relay switch with an output rated up to a limit such as 250 VAC / 5 amps. Some relay boards have an additional socket for a power pack connection. Other can be controlled remotely, or via radio frequency (RF). RF relay boards may use an auto-roll algorithm to prevent the unauthorized interception of transmissions. RF relay boards with transmitters and receivers use multiple channels.
As a rule, each channel has a reset connection for resetting the relay board when the device is used in toggle mode. Relay boards have a general purpose, high-current, or mercury-wetted switching matrix for routing signals and loads. They also provide a wide range of test signal switching options. Constant control relay modules or integrated relay control modules can be used as wide-open throttles in relays that are used in the normally closed (NC) condition. When operation is not required, the relay module is grounded and in a normally open (NO) condition. Constant control relay modules are also used with relay circuits in the cooling fans of engines and the operation of fuel pumps. The relay circuit n these relay boards causes the relay to toggle between the on and off conditions.
Relay boards are used in many different applications. Some products are used to control lights, motors, and other electronic devices in industrial and commercial applications. Others are also used to control heater temperatures, or are used in power switching applications Relay boards that are designed for specific types of industrial equipment are also available.