Digi EtherLite

Building:

• Fetch srpm. Install with rpm -ivv

  cd /root/rpmbuild/SPECS
  rpmbuild -bb dgrp-1.9.spec
  rpm --install RPMS/x86_64/dgrp-1.9-30.x86_64.rpm
  

Cabling

XREF ftp://ftp1.digi.com/support/cabling/90000253_E.pdf

For a standard RJ-45 to D-shell converter, the RJ-45 side enumerates onto colors as

Blue(1) Orange(2) Black(3) Red(4) Green(5) Yellow(6) Brown(7) White(8)

On Digi devices, these are labeled as

RTS(1) DSR(2) DCD(3) RXD(4) TXD(5) GND(6) DTR(7) CTS(8)

To make a female DE-9 connector for mating with a standard PC, its pinout is

DCD(1) RXD TXD DTR GND
   DSR RTS CTS RI(9)

Notice that there is no analog for ring indicator in the EtherLite, so we can’t bring that across. In any case, the mating pins are

DCD TXD RXD DSR GND
  DTR CTS RTS RI

(The Digi manual has a bizarre thing going on with DCD and DTR; it suggests shorting pins 1 and 6 of the DE-9 and leaving DSR (pin 2 of the RJ45) unconnected.)

Our final wiring schematic, ignoring the Digi funniness above, is, staring FORWARD INTO THE DEVICE, that is, with the colored wires facing you,

Black(DCD) Green(TXD) Red(RXD) Orange(DSR) Yellow(GND)
  Brown(DTR) White(CTS) Blue(RTS) N/C

Alternatively, with the Digi funniness it’s the less useful

Brown(DTR) Green(TXD) Red(RXD) Black(DCD) Yellow(GND)
        Brown(DTR) White(CTS) Blue(RTS) N/C

For DB-25M connections (A-side; if that doesn’t mean anything to you, ignore it), the pinout to color guide is

DB-25 Pin	RJ-45 Pin and Color
2 (TXD)	5 (Green)
3 (RXD)	4 (Red)
4 (RTS)	1 (Blue)
5 (CTS)	8 (White)
6 (DSR)	2 (Orange)
7 (GND)	6 (Yellow)
8 (DCD)	3 (Black)
20 (DTR)	7 (Brown)

Unfortunately, it looks like some of our serial converters ended up wired thusly:

Yellow Green Red Orange Black
  Brown White Blue   N/C

To compensate, rather than using straight-thru ethernet cables, crimp ones which are straight-through, except swap pins 3 and 6. This is even sort of convenient since those pins are on one twisted pair in standard Ethernet pinouts. Or just fix the connectors so we don’t end up with a pile of miswired Ethernet cables.

Some random musings

RJ45 DIGI	SERIAL	RJ45 SERIAL
1 WO	RTS	8 Br
2 O	DSR	2 O
3 WG	DCD	4 Bl
4 Bl	RXD	3 WG
5 WBl	TXD	6 G
6 G	GND	5 WBl
7 WBr	DTR	7 WBr
8 Br	CTS	1 WO

Equivalently, that means the “serial” end is: Br O Bl WG G WBl WBr WO

APC MasterSwitch

APC MasterSwitch uses a custom pinout. When making an adapter for one of those for use with a straight-thru ethernet cable, the pinout is, FORWARD INTO THE DEVICE, that is, with the colored wires facing you,

NC NC NC NC Red(RXD) Green(TXD)
  Black NC NC NC