Serial RJ45 cable

How do you make a RS232 connection between two DTE devices that uses RJ45 jacks as serial ports ?

I have a Systech terminal server, it has

1 DCD
2 RTS
3 SG
4 TxD
5 RxD
6 SG
7 CTS
8 DTR

and I want to connect to a Quantum PLC which has

1 DTR
2 DSR
3 TxD
4 RxD
5 SG
6 RTS
7 CTS
8 -

I guess I can cut a Cat5 cable in half and make the connection at a terminal block. but the handshaking loopbacks still have to be done on each invidural device.

Any ideas ?

try these guys:

www.rj485.com

the RJ45E-U-SM-BRK seems to have break-out, but it looks like you'd have to cut one CAT 5 cable and wire it to the terminal block.

Dan

Dan, the site you referred to is the scadaman's site. I think his post is a cheap plug for his products.

http://forums.mrplc.com/index.php?showtopic=11279

Gents,

I just post a rhetorical question to see if there is any device like this out there. Sorry for the misunderstanding.

I would go to my local electronics store and pick up a couple of RJ45 connectors and make the lead myself.

Mickey - I don't think Scadaman's post is an advertisement. The only reference to his site is in his profile, which anyone is allowed to have. Now, if he's in collusion with Danw - that would be an advertisement in two posts.

Gents,

I am raising in increasingly common issue that is happening in the automation industry. Vendors start using RJ45 jacks as RS232/RS485 serial ports. This creates a problem for those making custom cables. For example, I used to make a DB9 universal serial cable by loop back all the hand-shaking signals by jumpering DCD/DTR/DSR together and RTS/CTS together on both end of the cable INSIDE a DB9 hood since there is some room there. That leave only the RxD, Txd, and SignalGround. This cable works with every PLCs that I have run across. Now PLCs vendors ( Prosoft, Systech, Digi, Telemecanique to name a few ) start using RJ45 jacks as serial ports, making a universal serial cable becomes challenging because the RJ45 plug is so tight it is impossible to do local jumpering between pins anymore. Not to mention the pinout varies from vendor to vendor when it come to RJ45 pinouts ( see the first posting of this thread ).

I have came up with an idea of making an universal RJ45 adapter to handle the two abovementioned problems, but I know there are smarter and better engineers out there that ran into the same problem that I ran into. So I create this thread to toss this new concept around for the sake of discussion.

That's all.

Kind regards

Our problem is not with the RJ45 jacks themselves. We can easily creeate the correct connections for them. It's just to less knowing people they look just like Ethernet jacks and WILL plug Ethernet cables into them. We have found (in a manner you can probably guess) that RS485 and Ethernet don't like each other if they connect. I take pains to mark the RS485 communication jacks with a big NOT ETHERNET sticker.

It's just to less knowing people they look just like Ethernet jacks and WILL plug Ethernet cables into them. We have found (in a manner you can probably guess) that RS485 and Ethernet don't like each other if they connect.

Thanks Bernie I have looked at them side ways and wondered or worried that one day what will I do.

I have seen them in 8 pin and 10 pin and a Google showed up a 9 pin in a basic set up maybe 3 or 4 may exist

What do you use for "No ethernet" symbol?

Just the words

Not Ethernet