Table of Contents
Advertisement
Installation hints for best performance
This section offers several suggestions which will help you get the best performance from
your serial output.
1.
Use good quality low capacitance twisted-pair screened signal cable. CAT5
screened twisted-pair is ideal.
2.
The cable should be routed away from noisy wiring and devices such as power
feeds from inverters, discharge-lighting cables, welder cabling etc, and should
preferrably be routed in a dedicated low voltage signalling/instrumentation conduit
or cable tray.
3.
Screened cable should be earthed at the destination end only.
4.
All wires and screens coming out of the screened cable should be kept as short
as possible to minimise pickup of noise.
5.
If you are going to daisy chain several RS485 devices together on the same data
line, you should earth your screen as shown below, paying particular care that you
do not earth both ends of any run of of cable.
6.
Remember to fit a termination resistor to the instruments at each extreme end of
the cable run, but no termination resistor on intermediate units.
Receiver connection
With termination resistor
Remote
device
Connect screen
to earth ONLY
at this end.
Clean Earth
Receiver connection
With termination resistor
Remote
Length of screened cable
device
Connect screen
to earth ONLY
at this end.
Clean Earth
Length of screened cable
Link Screen but do
not earth at this point.
Display connections
Do not
connect
screen at
this end.
Display connections
Length of screened cable
Do not
connect
screen at
this end.
5
Advertisement
Table of Contents
