23 Sep
2013
23 Sep
'13
1:14 a.m.
On 22/09/2013 14:44, Roe Peterson wrote:
I think the answer to this is that you should check in every case. RS232
specifies two sorts of device, Data Terminal Equipment (DTE) and Data
Communications Equipment (DCE). It expects that you connect things as:-
DTE <=RS232=> DCE <=== comms link ====> DCE <=RS232=> DTE
So generally
a DTE is either a "computer" , a "Computer" configured as a terminal
concentrator or remote job entry (RJE) station or a terminal...
a DCE is a modem, or a modem eliminator, or some other communications
device such as a Gandolf PACX switch, e.g..
http://www.columbia.edu/cu/computinghistory/pacxbox.html
(note the Wiki page for Gandolf seems to be contaminated by political
infighting)
HOWEVER in many cases the boards in computers had links or switches and
could be configured as DTE or DCE...
Dave
G4UGM
If you're
using a terminal I would use a straight-through cable rather than the null modem. A
computer to terminal set up is DCE to DTE in the eyes of RS-232 and so no cross overs
should be needed.
Actually, both the computer serial port and the terminal are DTE devices. A null
modem cable is required.
DCE devices assert CD for carrier detect -- modems, for example. On DTE devices, CD is
an input. > Cheers,
>
> Andy.
>