DB9 Alternatives

Is size an issue as well as the secure locking of the connector to the device?

I have, in the past, used the Nuetrik XLR 6 pin for serial data-comms. These are very robust connectors and able to withstand quite a bit of maltreatment. If these are too large, then you may find some mini-din's (about the same size as the PS2 connectors) which are latchable. Not as robust but also a reasonable choice.

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What is commonly called a "DB9", isn't a DB9. It's actually a DE9. The DB form factor is the size that DB25 connectors have!

Regardless, there are DE9 connectors that lock. They are perhaps not as convenient as an RJ45, so if you are commonly changing these cords they definitely are not desireable.

You might want to consider using RJ45 with USB though...

20 years ago the AT&T 3B2 computers had serial port cards with 32 ports, all using RJ45 connectors. It was common then to use RJ45 to DB25 converters. Regardless, the point is that what you are considering is something which has been done, and worked well.

Note that you do *not* want to use twisted pair cable for RS-232 signals if the length and/or speed is at all significant. With short cables less than 10 feet, it would not be a problem; but if you have an odd one here or there that is 100 feet long, find some

8 conductor "flat satin" cable that is not twisted.

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For nearly full generality you need the 9 runs of copper. Send, Rcv, 2 supervision each way (rts, cts, dtr, cd), ring, common, and protective ground. Some of the mini-DINs should be useful, but do you really want to build your own cables? Also see what is in a TelCo supplies catalog.

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Generally, he won't need a Protective Ground on cables 5-10 feet long. Likewise the Ring line can often be left out, and depending on the application the CD and DTR lines can be combined. Not to mention that hardware flow control may or may not be needed.

A universal cable pretty much needs 9 pins; but most specific applications don't.

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Floyd L. Davidson           
Ukpeagvik (Barrow, Alaska)                         floyd@apaflo.com

And here I thought I might be the only person left who knew that . I've tried for years to persuade coworkers to simply refer to a "D9", as a less offensive alternative to the incorrect "DB9".

It might help to know what the OP means by not liking "the look" of the DE9. In the many years that small connectors have been designed, the D series remains one of the best all-around solutions, being reasonably robust, inexpensive, and relatively small for their pin count.

As good as they are for Ethernet use, for some reason, my experience with them in serial comms has not been all that good. For some reason, they have been less reliable.

Bill

Yes size is an issue, RJ45 is a pretty decent size. saw the Nuetrik XLR ones, boy they are expensive!

I don't want to spin my own cables for sure. it's quite amazing that there aren't too many alternatives to the DB9 (ahem.. DE9!!)

Interesting! So what do DA, DC, DD, etc look like?

Maybe a DIN connector. It would sure make the Mac customers happy. We used one on a product a while back because of similar space issues. It worked out well for us and wasn't too costly.

Good Luck

Scott

There are various methods of locking D type connectors from slide locks to screws and even retaining clips.

The PS2 connector *IS* a 6 pin Mini DIN, just like a SVHS connector *IS* a 4 pin Mini DIN. They are just normally non latching versions. The pins in Mini DIN connectors are a bit fragile and if making your own cables by using solder variants watch the iron temperature the nylon is easily meltable.

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In the "standard density" connectors, a DA shell holds 15 contacts, DB holds 25, DC is 37, and DD is 50. DE (perhaps an afterthought?) holds

9 contacts. The A, B, C and E shells are all the same width, but vary in length, and have two rows of contacts. The D shell is about the same length as the C, but is wider, with three rows of contacts.

There is a High Density E-size connector with 15 contacts, used on computer monitors.

Cannon (who I think originated this family) also make a Double Density series - the DA shell holds 31 contacts.

There are some variations that can have high current or coax contacts

- the A shell can have 3 of these contact.

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Well, actually it is a little confused. The DA/DB/DC/DD/DE indicates the length, while the number is how many pins there are.

Originally there was a DA-15, DB-25, and a DC-37, each being longer than the other, but the pins all have the same spacing. (Note that you'll see DA-15 connectors for joy sticks, but DC-37's are not so often seen.) There originally was also a DD-50, but that has three rows of pins, so it looks a little different.

The DE-9 seems to be an addon that came later.

There are others too (svga video connectors e.g.).

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Floyd L. Davidson           
Ukpeagvik (Barrow, Alaska)                         floyd@apaflo.com

I like Molex C-Grid connectors - small, inexpensive and with a really convincing click when they engage

Interesting. In the past, I've equipped several of my sites with RJ45 based terminal servers, used to connect DEC MMJ-based terminals, and making up my own leads. I never experienced any real problems, but I wonder now if I was lucky. What type of problems did you encounter ?

To the OP: The MMJ connector referenced above is a 6 pin RJ45 style (but a bit smaller) locking connector, but it's probably obsolete by now.

Simon.

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This may be of interest regarding RJ-45:

Richard

AFAIK the 6-pin RJ45 is a RJ12 connector. My experience is that where small size was an issue for EIA-232 comms, RJ12 connectors was used. The pin-outs are normally:

1 RX

1. CTS

3 GND 4 GND 5 RTS 6 TX

Hence by crimping the connector on the other side of the cable, One gets Rx connected to Tx etc.

Also by using an RJ12 in stead of RJ45, people wont plug your wire into an ethernet port. They might plug it into a telephone wall socket though.

Regards Anton Erasmus

Bit of history. :-) The Sinclair QL used a phone line like connector for its serial port, it worked rather well. The 68K Mac's (And some Amiga upgrades) used a Mini-Din like connector for the serial port. Both of these had cheap adapters to convert them back to the DE9 connector if needed.

But that is taken care of by having the GND on 3 and 4, where the telephone signals are :-)

Meindert

No kidding, I have been in the computer business as a techie for $25+ years and never knew that. I have learned something today. This is big news in my life because I come in contact with lots of connectors and always want to know the correct names.

examples:

DE15HD = vga RPTNC = linksys router antenna port