RS232 Physical Properties

These are the RS232 physical properties explained. See baud rates with distance as well. You can find the RS232 pinout on this website as well. These are the other characteristics of the RS232 interface which you might also find of interest. Below we will explain the communication methods capable of communicating in different environments. Note that voltage and distance is important with the RS232 standard. Also note the baud rates with distance as well as other specifications so look at the FT232R driver also on this website.

RS232 Physical Properties

Voltages differ and these do affect communication over the cables. As an example an RS232 with a -9.3 V, compared to -11.5 V has difficulty communicating with an industrial computer in a high noise environment. You will also note that there will be a difference in error levels over the two voltages.

RS232 max length

Cable length is also important and this does affect the communications as an example the maximum length is 50 feet, or the cable length equal to a capacitance of 2500 pF. That is very important as a  low capacitance cable will allow you to span longer distances and still be within the standard compared to a high capacitance cable. You should check the cable before you buy it. You will note the difference below as example cables according to the RS232 physical properties. See also the ft232rl driver setup. See also the rs232 to usb pinout on here. Likewise the USB to Serial Driver.

Likewise see also the Working principles of RS485 on here as well as the RS232 Cable Pinout.

Part Number : 2210 (Quabbin Cable)

Electrical Characteristics : (For 100m of Cable)
Capacitance, Mutual: 13.5 PF/FT. AT 1 MHz
Dielectric Withstanding, Min:  1500V RMS
Voltage Rating, Max: 300V

Part Number : 8508 (Quabbin Cable)

Electrical Characteristics : (For 100m of Cable)
Capacitance, Mutual: 13.0 PF/FT. AT 1 MHz
Capacitance, Mutual: 24.0 PF/FT. AT 1 MHz
Dielectric Withstanding, Min:  1500V RMS
Voltage Rating, Max: 300V

Part Number : 9508 (Quabbin Cable)

Electrical Characteristics : (For 100m of Cable)
Capacitance, Mutual: 15.5 PF/FT. AT 1 MHz
Capacitance, Mutual: 27.5 PF/FT. AT 1 MHz
Dielectric Withstanding, Min:  1500V RMS
Voltage Rating, Max: 300V

Part Number : 9720 (Quabbin Cable)

Electrical Characteristics : (For 100m of Cable)
Capacitance, Mutual: 15.0 PF/FT. AT 1 MHz
Dielectric Withstanding, Min:  1500V RMS
Voltage Rating, Max: 300V

Baud Rates with distance

There have been a number of options with regards to the baud rate an distance. The lower the baud rate usually the longer the cable can be. The example below was made by Texas Instruments in this regards. If speed is reduced as can be seen below by say a factor 2 or 4 then the maximum length increases as cab be seen from the table listed below. Se see the RS232 physical properties below. See also USB to RS232 Driver as well as the PL2303TA USB to RS232 DB9 Serial Driver.