Cable length

babber · Post by **babber** » Wed Jan 23, 2002 12:22 pm

What is the maximum distance between the serial port and a LK204-25? A "competitor" has said that 20 metres (60 feet) is too far for their LCD with a keypad. I thought serial was good for a hundred metres (300 feet)or so.

Cheers

Babber

Post by **Cheese** » Wed Jan 23, 2002 12:40 pm

I was always told null modem cables were good to 120feet and I see no reason (as long as you use a shielded cable) why you can't have one this long.

Cheers,

r.

Post by **Henry** » Wed Jan 23, 2002 12:42 pm

it all depends on the ground differential you may have... from the FAQ

The serial cable can be various lengths, mostly dependent on how well insulated the cable is, the thickness of the wires, what speed you will be communicating at, and how much background noise there is. At 19.2kBps the maximum safe distance is 50-200ft. At 9600Bps it is between 250-500ft.

More then anything, make sure to have LOTS of ground... since the serial cable has 9 pins, and you only need Rx, Tx, that leaves 7 for ground! Use them.

GomiBoy · Post by **GomiBoy** » Fri Nov 22, 2002 3:28 pm

If you're supplying +5V DC on pin 9 of the cable, you'll have significant voltage drop over that length & it probably won't work.

Post by **Henry** » Fri Nov 22, 2002 4:09 pm

that is true as well, you might even want to concider using +12V over the cable and a -V option LCD.