Diff. Serial / null Modem Cable

1

Hi,
the wiki says, you need a serial cable. no null modem cable for the serial interface.
Is this so or is there an “intelligence” that turns a crossed null modem cable 1: 1?

2

Which page? Please add a reference link.

3

For that, a serial cable is required.

4

If you need a 1to1 or a Null Modem depends on your hardware. For a regular PC serial port on the IPFire (e.g. on PC Engines APU) you need a null modem but e.g. for a Traverse Geos you need a 1to1 cable. On many arm boards you need a special serial cable with TTL level or even lower 3.3V level. To determine this check the hardware manual.

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5

@ Chris: Please, take Arne’s warning very seriously!

The original RS-232 allows voltages between [ -15V … -3V || +3V … +15V]
which can easily destroy modern Systems-on-a-Chip.

Besides, you need neither sorcery nor witchcraft, only a Connection Table,
to solder such cables to your need by yourself.
Up to 19.200 and short-range, it might even be sufficient to use a 3-Line (TxD, RxD, Ground),
configuring software-handshake.

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