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Thanks kam1787 for the links. Yes, I understand that there's no such thing as Ethernet Splitter, only RJ485 Splitter. I have a different question. Can I use a RJ485 Splitter to connect its second splitted end to a logic analyzer, or to a listerning-only device, all for the purpose of seeing what's travelling in the cable?
You are confusing the names, RJ45 is the plug commonly used for ethernet connections, RS485 is an electrical specification for data transmission, I've never come across RJ485.
In both cases it is possible to attach a receiver across the lines to monitor the traffic but difficult, if possible at all, to transmit into the wires. With RS485 you just attach a receiver IC (I use ADM488 and 489 devices or their Maxim equivalents) to convert the differential data back to single ended serial. With ethernet it is a bit more difficult because the lines are typically floating and terminated, you might need to use a hub as a signal splitter or make a high impedance differential receiver so you don't load the original signal too much.
You are confusing the names, RJ45 is the plug commonly used for ethernet connections, RS485 is an electrical specification for data transmission, I've never come across RJ485.
In both cases it is possible to attach a receiver across the lines to monitor the traffic but difficult, if possible at all, to transmit into the wires. With RS485 you just attach a receiver IC (I use ADM488 and 489 devices or their Maxim equivalents) to convert the differential data back to single ended serial. With ethernet it is a bit more difficult because the lines are typically floating and terminated, you might need to use a hub as a signal splitter or make a high impedance differential receiver so you don't load the original signal too much.
Thanks Brian. Yes it was just a typo, I meant RJ45 Splitter, or maybe more exactly signal splitter.
And I think you answered my question. A hub is not readily available over here. Can you tell if the input of a logic analyzer has already a built-in high impedence differential receiver? One is also not available here, I just wonder.
I have never come across a logic analyzer with differential inputs but you probably wouldn't need them. Just connect two channels, one to each line and you should see both signals, one normal and the other inverted. Some models may have a facility to perform math on the signals so you could invert one and add it to the other to get a representation of what a real receiver would see. I have several logic analyzers, oftern using them all at once on the same equipment but the best I have found is this one: https://www.saleae.com/logic
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