Category: Choosing a USB Relay Controller

Let’s start with a inductive loads and how they interfere with USB connectivity:  Inductive loads are high voltage or high current loads that involve a magnetic field.  A motor, solenoid, valve, transformer, pump, or any other device that causes motion or generates a magnetic field is an inductive load.  Inductive loads are particularly difficult to control for ANY USB relay board, as the electromagnetic interference does not stay confined and isolated to the relay as one might assume (though solid-state relays are superior to mechanical relays in terms of isolation). With regard to mechanical relays, USB relay boards may have

There are many ways to talk to USB relay controllers, some manufacturers choose HID or Custom USB communications to gain a performance advantage.  HID USB protocols do not require a driver, they use a standard HID descriptor to communicate relay control data.  Most computers support HID protocols, so HID commands are relatively easy to handle, but the software can be a little complex, so an extensive library of samples should be provided for all HID based USB relay boards. Other relay control manufacturers support custom USB descriptors, which require a driver for each platform.  These devices are more limited by

One of the biggest tech support questions and problems we have seen with all relay controllers (not just USB) is the unusual expectation that relays make a 0 Ohm connection between the Common and Normally Open or Normally Closed contact.  This is a huge misconception, which accounts for about 10 to 15 of our returns per year.  The real measurement between Common and Normally Open connections has been measured as high as 150 Ohms on a high-quality mechanical relay! The reason for the unusually high resistance is the simple fact that high-quality power relays, when new, include a anti-corrosive coating

Imagine you want to use a USB relay controller to control a heater, or maybe you want to control a water pump for irrigation applications.  How about using a relay board to control a gas valve.  Don’t think of using standard on/off commands for these applications, this is how you get into some serious trouble.  Computers are not fool-proof, communications is not fool-proof, you should be able to rely on the relay board to handle dangerous applications automatically.  A quality relay controller must have a timer mechanism for controlling relays for a period of time.  This will force a relay

Being a relay controller manufacturer means we have to answer to customers when things go wrong.  When it comes to power, there are plenty of opportunities for things to go wrong.  Powering a USB relay controller has to be met more caution than you might realize. USB Powered Relay Boards High-power mechanical USB powered relay boards are absolutely prohibited as per USB specification.  We lose a tremendous amount of revenue each year because we refuse to compete in the USB powered relay board segment of the market.  We are frequently contacted to be a supplier in this area.  The USB

Mechanical relays are clearly better than solid state-relays…but not really.  The fact is, you need to consider your application and your budget carefully before you choose a solid-state or mechanical relay solution.  Each has pros and cons, so rather than pick a side, it would be better to explore common uses of each, and see where your application lands. Mechanical relays are ideal for most applications, as cost is frequently a factor in deciding any technology solution.  Mechanical relays are capable of switching any type of load from small signals to high current, high-induction, audio, and sometimes video provided the

Controlling High-Power loads with the USB port is best accomplished with a combination of a large mechanical relay called a contactor and a solid-state relay controller.  When paired together, the computer can safely control the solid-state relay, and the solid-state relay will block the induction of the contactor from the computer.  Since a contactor contains a coil, it is an inductive load, and it must be managed accordingly with induction suppression components.  Contactors can be rated at many load and coil voltages, but keep in mind, most solid-state relays are rated for AC switching only.  A select few DC solid

I could not even begin to guess how many relays we have sold over the years.  Relay failures are extremely rare for both mechanical and solid-state relays.  We always try to work with our customers to choose the correct size of relay for a given load, and to determine the cause of failure on those rare occasions.  The majority of relay failures we have seen are related to overcycling the relay (turning the relay on or off far more frequently than rated), lightning strikes, and of course your basic misuse (too much current or voltage flowing through a heavily cycled

The speed of a relay switching operation will help define the lifespan of the relay.  Mechanical relays often have a activation time of 5-10ms, with a deactivation time of 10-20ms.  As a general rule, high-speed switching of mechanical relays will cause physical contact wear.  Solid-state relays are better suited for high-speed switching applications, but they are not immune to the effects of high speed switching.  Users of solid-state relays for high-speed switching applications should monitor the temperature of the solid-state relay.  High-speed switching can cause the temperature of the SSR to rise, particularly when switching high-speed inductive loads.  Inductive loads

Manual and computer control is a basic function built into all USB relay controllers we have manufactured for many years.  Manual control allows you to control a relay from the USB port or manually through an external input.  Relays are controlled manually when a analog input is first mapped to a particular relay.  Once mapped, the analog input has control of the selected relay.  When the analog input is high, a relay can be set to activate.  When the analog input is pulled low, the relay will deactivate.  This allows sensors and limit switches as well as the USB port