Selecting Rs-485 Termination Resistors - GE VME DLAN User Manual

Selecting RS-485 Termination Resistors

GFK-1044A
If the RS-485 network is selected, the drop at each end of the network cable should have the
termination resistors IN. This is true for all drop types, both DLAN modules and drives.
Adding additional termination resistors will improve the signal to noise ratio of RS-485
networks, but more than five sets of termination resistors will overload the drivers.
Accordingly, no more than five drops on a network should have the termination resistors IN.
Table 2–2 shows the jumper settings for termination resistors. At the factory, these jumpers are
set for termination resistors IN.
Table 2-3. Jumper Positions For RS-485 Network Termination Resistors
Jumper
JP5
JP6
If the optically isolated network is selected, the termination resistors are not used, and the JP5
and JP6 jumper settings are ignored.
Chapter 2 Installation and Initialization
Termination Resistors
IN
1 – 2
1 – 2
2
OUT
2 – 3
2 – 3
2-7