Hardware manual

PCI VELOCITY / OPTO ISO RS422/485 RS422/485 Information
Chapter 4 Page 47
remain in the receive only mode when they are not being addressed,
they do not transmit any data at all. Figure 4-5 gives the jumper
settings for the serial card in the RS485 Full Duplex mode.
Figure 4-5. RS485 Jumpers, Full Duplex.
• Both jumpers left unconnected (not shorted).
Figure 4-6. RS485 Full Duplex.
Note: The receiver end of MAIN line terminated in characteristic
impedance, stubs off the main not terminated.
Optional Grounding Arrangements.
Proper operation of the cable circuit, according to TIA EIA:
485 A (1995) requires that the cable ground shield is not connected
directly to the equipment ground shield. A current limiting resistor
should be used in series with the shield to avoid possible large