Serial Port Data Transmission

[sao123]

What is the maximum effective length of a serial date cable (DB9) for a 9600 baud transmission?

 

[Modelworks]

It really depends on if the you are talking about a true rs-232 port or are talking about a laptop port. The difference is a true port will have voltages that swing between -12V and +12V some even go -15V to +15V while laptops tend to be 5V to ground.The lower voltages used cannot send the signal as far because the resistance of the wire will cause the bits arriving at the end to look the same. With a true serial port you can get 25ft easily, perhaps more but I never tried. If you really want to go distance you should look at rs-485 it was designed for distance.

 

[sao123]

we do use laptops, but only in a powered docking station.

The application is a GL400 Storm Guard Download... (http://www.certifiedpower.com/downloads/sgl/SGL0105000101.pdf)
we already use 30ft cables... I need to know if I can go 60+ ft...

Certain places I cant get a mack size snowplow within 30 feet of a building.

 

[pitz]

Do the laptops not use some sort of chip like a MAX232 to re-create the bipolar power supply necessary for RS-232?

Or was that ommitted for some reason?

I agree with the other poster, RS-485 (ie: differential signalling) is a better idea for distance. Or even using something like wireless or Ethernet to some sort of terminal server device if possible.