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What is difference between single ended and differential inputs?
Single-ended inputs are lower in cost, and provide twice the number of inputs for the same size wiring connector, since they require only one analog HIGH (+) input per channel and one LLGND (-) shared by all inputs. Differential signals require signal HIGH and LOW inputs for each channel and one common shared LLGND.
What should voltage be between hot and ground?
You have to measure neutral-ground or hot-ground. If neutral-ground voltage is about 120 V and hot-ground is a few volts or less, then hot and neutral have been reversed. Under load conditions, there should be some neutral-ground voltage – 2 V or a little bit less is pretty typical.
Why do you need common ground in differential signals?
Even though it’s differential, you do need to constrain the common-mode range. That’s what the common ground is for; it keeps the references somewhat equal so that the common mode isn’t influenced by a floating Tx, Rx, or both.
When does a signal need a ground connection?
They require a ground connection to keep the signal at the receiver’s end of the bus within the common-mode range of the receiver chip. Often such systems stop working when the voltage offset is more than a few volts, and can be permanently damaged if the voltage offset ever reaches a few dozen volts.
How are differential signals detected in a receiver?
There are 3 main types of receivers used to detect “differential signals”: RS-485, RS-422, CANbus, LVDS, USB, SATA, PCI Express, etc. directly connect differential signals to the receiver chip — “DC-coupled”. They require a ground connection to keep the signal at the receiver’s end of the bus within the common-mode range of the receiver chip.
When do you need a ground wire for CANbus?
When sending RS-485, CANbus, etc. over a cable, typically at least 1 wire in the cable is reserved for the ground wire, which pulls the system ground at one end of the cable and the system ground at the other end of the cable closer — hopefully close enough to allow communication or at least to prevent permanent damage.