a question about connector from DB25F to DB25F (RS232 cable)

[samuel16]

I want to connect from DB25F(a cable end) to DB25F(a device interface). All are RS232 cables.

The pinouts of them are same. Could I use a straight cable adapter (DB25M--DB25M)to connect them or I must use a DB25M--DB25M null-modem cable adapter?

Could you please give any suggestions?

my email: [edit Rob - email deleted: posting on a forum is a great way to get spammed]

Thanks.

[PS1]

I doubt it ll be long before someone on here asks you why? and what you are trying to make

[SimpleSimon]

Just use a straight through cable 25M to 25M

[popper]

Originally Posted by samuel16

I want to connect from DB25F(a cable end) to DB25F(a device interface). All are RS232 cables.

The pinouts of them are same. Could I use a straight cable adapter (DB25M--DB25M)to connect them or I must use a DB25M--DB25M null-modem cable adapter?

Could you please give any suggestions?

my email: [edit Rob - email deleted: posting on a forum is a great way to get spammed]

Thanks.

the generic DB25M--DB25M for gender changing is what you use in this case.

a null-modem connector will swap the tx and rx over and not what you want to use for gender changing,nulls are for PC to PC communications.

[samuel16]

Originally Posted by PS1

I doubt it ll be long before someone on here asks you why? and what you are trying to make

What we have:
1. Kinemetric's Altus K2 data loggers

The data loggers are configured to output a Serial Data Stream (SDS) through their RS-232 port. The SDS is connected to an External Device Server.

2. External Device Server: Lantronix UDS1100
Firmware Version: V6.5.0.0


Problem:
The interface on K2 loggers are a rounding one. We have a cable connected to the K2 logger and the other end of this cable is DB25F. While, the interface of the UDS1100 is also DB25F.

My Solution:
So I bought a cable adapter with: DB25M---DB25M. One end to the UDS1100 and the end connected with the end of the cable(which connected to the K2 logger).

Not Work
Now I can found the UDS1100 server in my computer, but no data streaming from K2 logger.



And the following is the response from the LanTronix Technical Support:

Hi Samuel,

Instead of a straight-through DB25M-DB25M gender changer please try a DB25M-DB25M Null Modem adapter similar to the one shown at the site below:

http://www.cablestogo.com/product.as...=106&sku=02471

Background:
==========

There are two basic types of RS232 connectors, DTE and DCD. DTEs include the serial Com ports on a PC, and the serial ports on most dumb terminals and serial printers. DCEs include most serial modems and the UDS1100.

A rule of thumb is that DTEs are usually male and DCEs are usually female. The idea is that DTEs will always be connected to DCEs using a straight-through male-to-female cable. However, if you want to connect a DCE to another DCE or a DTE to another DTE you need to use a "null modem" cable to swap the signals around so they're connected correctly.

I suspect that's what the problem is here, the UDS1100 is a DCE and the cable from the loggers are pinned as DCEs.

For more information about serial cable wiring see the FAQ at the link below:

http://ltxfaq.custhelp.com/cgi-bin/l...php?p_faqid=25