Proface PS4800 - 19 Panel PC" - Manual (Page 105)

PS-4700/4800 Series (Atom N270 / Core 2 Duo P8400 Pre-installed Model) User Manual
105
RS-422 - Bus length and cable type
The RTS line must be switched on to activate the sender.
The maximum transfer rate of 115 kBit/s depends on the cable type being used.
The material used for the cable should preferably have all or most of the following properties
in order to reach an optimal transfer rate.
RS-485 interface operation
The pins of the RS-422 default interface (1, 4, 6 and 9) should be used for operation. The pins
should be connected as shown.
The RTS line must be switched each time the driver is sent and received; there is no automatic
switch back. This cannot be configured in Windows.
The voltage drop caused by long line lengths can lead to greater potential differences between
the bus stations, which can hinder communication. This can be improved by running ground
wire with the others.
The line ends of the RS-485 interface should (at least for longer line lengths or larger transfer
rates) be closed. Normally a passive terminator can be used on the bus ends by connecting
each of the signal lines with 120
Ω resistance.
Distance [m] Transfer rate [kBit/s]
1200 Typ. 115
RS-422 cable Property
Signal lines
Cable cross section
Wire insulation
Conductor resistance
Stranding
Shield 4 x 0.25 mm² (24AWG/19), tinned Cu wire
PE
≤ 82 Ω/km
Wires stranded in pairs
Paired shield with aluminum foil
Grounding line
Cable cross section
Wire insulation
Conductor resistance 1 x 0.34 mm² (22AWG/19), tinned Cu wire
PE
≤ 59 Ω/km
Outer sheathing
Material
Characteristics
Entire shielding PUR mixture
Halogen free
From tinned cu wires
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