Datasheet

LTC2872
16
2872f
FuncTion Tables
Table 5. RS485 Driver Mode for a Given Port (485/232 = 1, TE485 = 0)
DXEN DY CONDITIONS Y Z
0 X No Fault 125kΩ 125kΩ
1 0 No Fault 0 1
1 1 No Fault 1 0
X X Thermal Fault 125kΩ 125kΩ
Table 6. RS485 Receiver Mode for a Given Port (485/232 = 1, LB = 0)
RXEN A–B (NOTE 5) CONDITIONS RA
1 X No Fault Hi-Z
0 < –200mV No Fault 0
0 > 200mV No Fault 1
0 Inputs Open or Shorted Together (DC) No Fault 1
X X Thermal Fault Hi-Z
Table 7. RS485 Termination for a Given Port (485/232 = 1)
TE485 DZ H/F, LB CONDITIONS R(A TO B) R(Y TO Z)
0 X X No Fault Hi-Z Hi-Z
1 0 X No Fault 120Ω Hi-Z
1 1 X No Fault 120Ω 120Ω
X X X Thermal Fault Hi-Z Hi-Z
Table 8. RS485 Duplex Control for Given Port (485/232 = 1)
H/F RS485 DRIVER OUTPUTS RS485 RECEIVER INPUTS
0 Y, Z A, B
1 Y, Z Y, Z
Table 9. Loopback Functions for a Given Port
LB RXEN TRANSCEIVER MODE
0 X Not Loopback
1 1 Not Loopback
1 0 Loopback (RA = DY, RB = DZ)