View Full Version : RS232 Cable extending

23-01-2017, 02:24 PM
Hi all

Been a member for a while now, and have finally acquired a Tekcel V-Series 8x4 router. I'm looking after the computer end of the set-up at our workshop and have hit on a possible snag.

There is a 50ft RS232 cable that came with the machine but I am about 6ft short to connect the PC to the router with the space we have available. I know that 50ft is the standard max length of these cables, so my question is really I can extend it with another 2m cable screwed into this one, or whether I am likely to experience problems of any sort?

Also, with that sort of connection, any tips on what kind of cable would be best to buy? I have heard the terms 'handshaking' and 'non-handshaking' but I don't know if it makes any odds to this situation.

Thanks in advance for your any help!

23-01-2017, 02:54 PM
Try it an see - 50 meters is not a hard limit. You could test with a multi-meter how the existing cable is wired, but to extend it all you need is a cable that connects pin 1 to pin 1 ... pin n to pin n.

23-01-2017, 04:28 PM
Thanks for the reply. I know it's not a hard limit, and I guessed there would probably be some headroom, just not sure how much as I know the signal quality does get degraded over distance with these cables. I'll pick up a normal cable later and see what happens...

Robin Hewitt
23-01-2017, 09:31 PM
There are two kinds of handshaking with IBM RS232, hard wire and Xon Xoff.

Xon Xoff are ASCII characters, basically sending an Xoff is the equivalent of, "Shut up" and Xon means "Resume transmission".

Wire involves 2 wires, One end could raise RTS, Request To Send, then wait until the other raises CTS, Clear to send, before sending the data. Data Terminal Ready, Data Set Ready are similar. Ring Indicator is to say someone is trying to dial your Modem.

Wired handshaking is uncommon, but very often people wire CTS back in to RTS and DTR back in to everyone else for instant gratification.

Back in the day the notion was that a fancy screened RS232 cable was good for 10 feet while twisted pair was good for 100 yards.

23-01-2017, 09:38 PM
If it does prove to be a problem, you could look into either RS422/485 converters, or having just done a quick google, you can get RS232 repeaters/range extenders.

The same google search threw up this supplier, with various options - http://www.tronicore.com/en/rs232-rs485-rs422-converters

26-01-2017, 11:57 AM
Thanks a lot for that info m_c - the machine will be online tomorrow and if I do have any issues I will look to one of those solutions.

27-01-2017, 05:32 PM
Well, to confirm, and for anyone else in a similar situation in future, my cable has worked out no problem. I have extended a 50ft serial cable with an additional 6ft and also it runs parallel with some power lines in places (unavoidable) and there are no data transmission issues with the machine.