ManT1S network termination

What is termination, and why is it needed?

When waves crash against a wall, they bounce back to where they came from. When a guitar string is plucked, it keeps ringing because both ends are stuck and bounce the wave back into the string, producing a standing wave. This may be great for making music, but it is a problem if you're trying to send a single wave containing data through a medium, such as a wire. You don't want old data to keep ringing in your wire while you're trying to send new data!

To prevent this, you need to terminate your transmission line so the wave gets absorbed at each end. Doing this is called "termination". Regular Ethernet does this inside every device, and can get away with that because Ethernet connections are always point-to-point with one device on each end of the cable. So you don't need to think about it: it's always done for you.

A T1S mixing segment on the other hand can have multiple devices (up to 8 officially) in a chain, and only the nodes at the end should terminate the transmission line, not the ones in the middle. So, this is something you, the ManT1S user, need to take care of.

Termination on The ManT1S

There are two ways to enable termination on the ManT1S. The first one is closing the JP1 and JP2 solder jumpers on the top side of the board:

The second one is shorting both sides of the JP3 jumper on the bottom:

This second way is mostly intended for if you are surface mounting a ManT1S onto a carrier board and you want to export the termination selection to your own board. The KiCad footprints have pads to connect to the pads of JP3 for this purpose.

Termination on the ManT1S-Bridge

On the ManT1S-Bridge, you can enable termination by having jumpers JP1 and JP2 (the two that are together) closed:

Termination using a ManT1S-Gadget

When the ManT1S is integrated into a device, it may be inconvenient to have to open it to enable or disable termination. For this reason, the ManT1S-Gadget was created, to provide a simple way to terminate the T1S mixing using only external connections.

This little board can inject power with proper filtering (purple and white wires in the image), or you can enable termination for the T1S mixing segment with the JP1/JP2 jumpers bridged, or you can do both if this is an end node that also injects power. It's pretty much just a low cost electrical interface to the network, broken out on a tiny board by itself.