Near Intersection of I-35 & I-90 Southern Mn. | My experience with CAN and the terminators is that it is desirable to have a terminator on the extreme "ends" of the CAN connector chain of devices. Generally this means one near the display (often built into the wiring) and the other at the last branch to the most distant module.
I have also found that "not" following these rules does not automatically guarantee a problem. In other words, you may be able to "get by" without following the suggestions for terminators.
The purpose of the terminator is to prevent "reflections" and thus noise/interference in the communication between the various modules. I suspect the noise/interference can vary from situation to situation depending on what is being used etc. Most systems have some type of error checking which uses a clever scheme to insure that the data received is complete and if not so, the receiver calls for a repeat. We as operators are not aware of this if it happens only occasionally.
The terminators are generally just 120 ohm resistors placed across the CAN HIGH and CAN LOW wires. Since there are two of them wired in parallel, the net effect is 60 ohms. This tends to "deaden" minor interference since the CAN HIGH and CAN LOW signals are symmetric opposites. |
Dust Cover for Ag Leader CAN A Tractor/Power Cable
