XW inverter Xanbus wiring questions?

new2PV

HI, the manual says the Xanbus wires must be no shorter the 6 feet. Does this mean each cable to each device or the total length of the cables combined? Do you have to terminate the 2nd Xanbus port in the inverter if you only have one cable piggy backed to the devices?

BB.

In general, this type of specification for networking cables means that the device to device connection should be a minimum of 6 feet--Even if they are right next to each other (coil up excess wire--Technically, the "proper coiling" for excess cabling is a figure 8 for various reasons).

What happens is that a cable as a "characteristic impedance" based on its inductance and capacitance. When you plug in a device (receiver/driver chips) they have their own capacitance. If you put three or more devices next to each other, the capacitance of each transceiver "lowers" the characteristic impedance of the cable--And this means that if you have another device 100 feet away sending signals to the other three devices, the "miss-match" of impedance will cause some of the signal energy to be reflected back to the transmitter device and you will have lower signal amplitudes at the receiving cluster.

If you put >6 feet between each device, then the overall characteristic impedance of the cable is (on average) not "harmed".

It is not usually a "black/white" issue--Your system may work fine, or as you add more devices, the "bus" gets noisy and data transfers slow down. Depending on the software, you may or may not see data errors/bus usage flags/error messages.

-Bill

SkiDoo55

On second question yes you should put the terminator plug in any unused open ZanBus ports. One should have come with each device

new2PV

Ok thanks, everyone, I just thought 6 ft of cable is excessive, I was going to order shorter cables...