Question: I am trying to hook up my sign to a PC that is some 80 feet away. In my office downstairs I have the 25-foot RS232 cable supplied by AMS going from my Serial Port to a CAT5 jack in the wall. From there I have about 75 feet of CAT5 cable going to another CAT5 jack near the sign upstairs. Then I have a 6-foot, 6-wire modular cable going to the sign. It doesn't work. I have tested all of the cables and they're good. I tried lowering the baud rate to 4800, as someone suggested, with no luck. I'm not getting anything on the sign - the old message that I last transmitted with the shorter cable is still on the sign untouched. It looks like there's no communication with the sign. Do you have any suggestions?

Answer:

1. Your overall cable length shouldn't be a problem if you shorten the cable in your office between your computer and the wall jack in your office. You wrote that you're using the AMS 25' Modular Serial Cable. 25'+75'+6' is pushing the envelope on cable length. So cut off what you don't need in your office. Be sure to put the new six-conductor RJ11 plug on the end correctly. When holding both ends of the cable side by side, the blue wire should be on the same side on both ends. Check out the end you cut off, and put the new plug back on the same way. Or order a short, straight-through cable from Alpha-American Programmable Signs or from somebody who can make you one.
2. Check the 6' cable connecting the sign to its wall jack. Where did you get the cable? Is it a 6-conductor RJ11 cable? It has to be. Is it straight-through (blue wire on the same side on both ends)? It has to be. You said it's short. That's good. Can it be shorter?
3. Now let's review the 75' CAT5 cable. Did you pull the 75' CAT5 cable from the sign jack to the computer jack, or was it already in place? If it was already in place, do you know if it branches off in any other directions to any other jacks? It can't. It has to be exclusive to these two jacks. Does it have a lot of excess cable coiled up somewhere inside the wall or above the ceiling? Most cable contractors leave lots of excess cable coiled up, so you can move the jack if you have to. If so, eliminate the excess. What is important is actual cable length, not the distance from point to point. Try to keep the total as much under 100' as possible.
4. Now let's address the wall jacks in your office and behind the sign. You said that you are using CAT5 jacks. Do you mean Ethernet RJ45 jacks? AMS serial sign cables use 6-conductor RJ11 modular plugs. They are not a good fit in an RJ45 jack. There is an adapter that you can buy to go from RJ45 to RJ11, if you are compelled to keep using your RJ45 jacks. Did you install the CAT5 jacks? If not, were they going to be used for 10BaseT or 100BaseT? 10BaseT uses 2 pairs (not enough); 100BaseT connects 4 pairs (8 conductors is 2 more than we need).

In conclusion, if you want to get this job done quickly and easily:

1. Verify that only 75 feet of CAT5 cable runs between the two jacks.
2. Remove the two RJ45 wall jacks. Go to your local hardware store and purchase two six-conductor RJ11 telephone phone wall jacks.
3. Pick six wires out of the CAT5 bundle (white-blue, blue-white, etc.) and connect one wire to each of the six screw terminals on the two new wall jacks. Write down which color wire you connected to each terminal in the wall jack and wire both jacks identically. NOTE: CAT5 wire is very fragile. A couple of bends, and it breaks very easily. If this happens where you can see it, no problem. If it happens in the cable or behind the jack, then you'll be pulling your hair out trying to figure out why your perfect cabling job isn't working. That's one good reason why AMS recommends 22AWG shielded wire for sign applications. It doesn't break, and it isn't usually affected by other devices nearby.
4. Re-connect the two modular cables and transmit your message.