User`s manual

22 Introduction
Figure 1-16: Sourcing DO: Slider # of Switch 5 is ON
1.5.7 RS-485 Connection
PCIe-2602 supports RS-485 protocol
To avoid signal reflections, each bus segment must be blanked at
its physical beginning and end with the characteristic impedance.
A resistor, Rt, is installed for this purpose, with – 130 ± 2% the
API(DO Output)
DO Out# to
Connector
1 Low (0V)
0 High (+5V)
DO# (From
FPGA)
Darlington
Driver
Clamp
DO Out# (To
connector)
GND
+5V
User Device
Load
User DI
PCIe-2602
330
S5