If you specify hardware handshaking then you do need pin 20.  I've never done this.  I've only used transmit, receive, and ground; pins 2,3, & 7 and never had a problem.
Somewhere in my collection of manuals I should have this schematic.  If I find it I will see if it gives further details.

Larry Barnes

Tom Hula wrote:

> Maybe I am missing something here.  I am looking at the DTC Cabling and
> Racking Guide ... on page 2-27 (RS232 RJ45 connection to HP terminals
> and HP printers), it indicates this scheme:
>         RJ45                    25-pin male connector
> Pin       1     ------------         2 - TD OUTPUT
>           3     ------------         3 - RD INPUT
>           6     ------------         7 - SGND
>
> And then, if you are using hardware handshaking, use the same pins and
> add:
>           4     ------------        20 - DTR OUTPUT
>
> So, if I am using serial printing from a DTC and using printer type
> 22, does it matter whether I add the fourth pin?  I suppose it depends
> on whether I specify hardware handshaking or not.  Right?  So, is the
> book right or not?
>
> "L. A. Barnes" wrote:
> >
> > Wesley,
> >
> > I pulled out my handy dandy HP Data Terminal Cabling Manual (its been out of print for some time now) and pin to is the transmit and pin 3 is receive.
> >
> > If you have a standard DB-25 to RJ-45 connector (you can get them from your local Radio Shack, or other electronics outlet) you can configure this connector any way you want.  Simply coordinate the RJ-45 cable to
> > match the pins in the DB-25.  I used the Red for pin 2 and Green for pin 3 on the DB-25 side of the connector.
> > You may need to switch pins 2 & 3 on one end of your cable depending on the way your printer is configured.  If so simply use a pair of needle nose pliers to push the pins out on the DB-25 and switch them.
> >
> > Hope this helps
> >
> > Larry Barnes
> >
> > Wesley Setree wrote:
> >
> > > I have a DTC  16mx and I need to attach an HP2566 printer to one of the ports. I have RJ45 connectors on both ends of my comm line. If I am looking at the RJ45 with the metal prongs sticking up my color scheme is:
> > >
> > >    1           2          3         4        5        6         7        8
> > >  white   orange  black   red    green  yellow  blue   brown
> > >
> > > How do I pin out to the printer side? On my 25-pin converter, I am using:
> > >
> > > pin 2 - 3rd prong   pin 7 - 4th prong   pin 3 - 5th prong
> > >
> > > I guess my question is....what lines coming from the DTC16mx are for transmit, receive and ground? On my 25-pin connector, is 2 transmit or is it receive?
> > >
> > > Wes