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The SLCs and the EDSs are RS232 only, but they internally jumper pins 4 and 5 to signal ground, so if the TX- and RX- pins on an RS423 device are connected to an SLC or an EDS the connection will "become" an RS232 connection.
This is how folks connected RS232 devices to ETSs, SCSx00s, etc. They just connected both of the return pins on the Lantronix RJ45 connector to signal ground on the RS232 device. See this article: RJ45 Serial Pinouts and cables for Lantronix console and device servers
If you have some old RS423 devices (e.g. old DEC VT terminals) you should be able to plug them into an SLC or EDS with a simple rolled cable:
VT Terminal SLC or EDS
MMJ RJ45
NC 8
DTR 1----------7 DSR
TX+ 2----------6 RX
TX- 3----------5 SGD-|
RX- 4----------4 SGD-| (internally jumpered)
RX+ 5----------3 TX
DSR 6----------2 DTR
NC 1
The connection will be limited to RS232 cable lengths because the SLC and EDS RJ45 serial connectors use RS232, not RS423.
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