Rs 422 Cable Impedance

Rs422 differential was designed for greater distances and higher baud rates than rs232.

Rs 422 cable impedance.

2 1 selected rs 422electrical specifications. The tolerance on the cable impedance is nominally 20 144 to 96 ohms. Figure 4 shows the cross section of a four pair utp cable typically used for two full duplex networks. Category 5 cable is available as shielded twisted pair stp as well as unshielded twisted pair utp and generally exceeds the recommendations for rs 422 making it an excellent choice for rs 422 and rs.

Rs 422 to illustrate their basic differences a condensed description of each standard is presented in the following subsections. The texas instruments sn65hvd37 ic used in this example includes a 3 state enable input to force the two driver outputs into a high impedance state. In general higher impedance cable will yield better results. The characteristic impedance of the cable zo and is used only once at the end of the cable.

It doesn t matter what serial comms method you employ or what the nominal cable impedance is. Can be accommodated with rs422. Rs422 to uart interfacing. The cable has a maximum capacitance of 17 pf ft 14 5 pf typical and characteristic impedance of 100 ohms.

While the rs 485 specification does not specify cabling these recommendations should be used for rs 485 systems as well. The receiver also includes an enable signal equipment manufacturers could use to turn off the receiver. It was intended to replace the older rs 232c standard with a standard that offered much higher speed better immunity from noise and longer cable lengths. Similar cables in two pair and single pair versions are available to.

Interfacing an rs422 driver and receiver. Category 5 cable is available as shielded twisted pair stp as well as unshielded twisted pair utp and generally exceeds the recommendations for rs 422 making it an excellent choice for rs 422 and rs 485 systems. Industrial rs 485 cables are of the sheathed unshielded twisted pair type utp with a characteristic impedance of 120 w and 22 24 awg. Figure 5 an example of a pull up and a pull down resistor on an rs 485 bus to ensure the proper voltages on an inactive bus.

While the rs485 specification does not technically specify cable impedance the rs485 driver ics do have their limitations and lower impedance cable can cause loading problems and or reduce noise margins. Take a look at thispicture for a 50 ohm system. Of specialty rs 422 485 cabling. Rs232 and rs422 isolated and esd protected 1.

The cable has a maximum capacitance of 17 pf ft 14 5 pf typical and characteristic impedance of 100 ohms. Rs 422 systems can transmit data at rates as high as 10.