regoli@silver.bacs.indiana.edu (michael regoli) (07/20/88)
]:[ my thanks to everyone who responded to my question regarding serial cable lengths! my mailbox exploded with very kind replies. just in case anyone else was wondering (i know there are a few), i'm excerpting portions of the responses. thanks again! == 30 feet -- no problem... the rs232 spec says 50 or 100 ft... == I have a connection between a sun and an IBM/PC, and use a baud rate of 19200 with the mskermit terminal emulator and file transfer functions with no problems. The distance is at least 100 feet. == Some people may tell you not to do it, but 30 feet is fine. We have gone up to apx. 200' with shielded cable, apx. 90-100 ft with telco wire. I think it mostly depends on your environment. Remember that the 'R' in RS232C is "Recommended". I've run a serial cable 50' or so in a modular office environment withouth any problem. I've had problems in a "computer room" running one 10'. If it's reasonably shielded, go for it. == Serial you say? If its RS232-C (the most common serial comm port), there should be no problem at 1000+ feet. The official IEEE standard says no more than 50 feet is recommended, but much greater lengths are commonly used. Use 22 or 24 AWG stranded cable with at least one common shield (its the cheapest) and you'll have no problem. A good indicator of RS232-C is 25 pin slots (or pins if you've got solder type (yuck)) plus a D shaped plug. The plug type is often referred to as dee-bee-twentyfive adapters, plugs or what have you. Baud rate will have no influence unless your cable is unshielded and its next to high voltage or radio emissions. Hope this helps! == The RS-232C spec calls for cables up to 50 feet at speeds up to 9600 bps, so your 30-foot cable is well within spec. == No problem. EIA (RS-232) should be able to go 50 ft at baud rates up to 19.2 if the equiptment is using standard drivers, and almost all the PCs that I know of do. If you're still unsure, try connecting it up while its all sitting on one desk with the cable coiled on the floor, you won't blow a driver or anything. Good Luck! == If it's shielded, you should have no problem at thirty feet. We have run LN03's at more than seventy feet and had no problems. == You should be able to do what you propose without problems. I think that's more than the standard calls for, but we have run up to 100 ft at 76.8k, so I expect your application to work fine. If you have trouble, there are driver chips on the serial board which do the actual driving of the +/-12v lines. There is a higher power driver chip available in many cases. If you have problems you should contact a hardware guru to find out if this can be done in your case. == Don't worry, you should be more than safe. We have a serial line used for the same purpose that is approximately 75 feet running at 9600 bps also. Good luck, laying cable is really enjoyable work. 8-} == 30 feet is WELL within the viable length of rs232 (the serial spec). I don't have my rs232 spec handy, but the maximum length of a cable is something like 200 ft. == In the past I have run "unshielded" 2 pair (22 awg) cable over 250 ft. without any problems. The cables were connected to dumb terminals running at 9600 bps. When I wired our new location I used Belden 8723. It is 22 awg. 4 conductor with a drain wire and foil shield. I connected our Apple laserwriter to our Vax....approx 125 ft. away...and never had dropout. ------------------------------------------------------------------------------- michael regoli | ihnp4!iuvax!silver!regoli | regoli@silver.bacs.indiana.edu -------------------------------------------------------------------------------