Technical data • Individual components
Chapter 2
Technical data
Automation PC 810 with GM45 CPU board user's manual V1.28
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RXD
RXD
TXD
TXD
9
6
4
1
DATA
DATA
Figure 74: Add-on RS232/422/485 interface - Operated in RS485 mode
The RTS line must be switched by the driver for each transmission or reception; there is no automatic switch-back
mechanism. This cannot be configured in Windows.
The voltage drop resulting from long cable lengths can lead to greater potential differences between bus stations,
which can hinder communication. This can be improved by running ground wire with the others.
The line ends of the RS485 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 a 120
Ω resistor.
3.10.3.9 RS485 - Bus length and cable type
The maximum transfer rate of 115 kbit/s depends on the type of cable being used.
Distance [m]
Transfer rate [kbit/s]
1200
Typ. 115
Table 129: RS485 - Bus length and transfer rate
The material used for the cable should preferably have all or most of the following properties in order to reach an
optimal transfer rate.
RS485 cables
Property
Signal lines
Cable cross section
Wire insulation
Conductor resistance
Stranding
Shield
4x 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
1x 0,34 mm² (22AWG/19), tinned Cu wire
PE
≤ 59 Ω / km
Outer sheathing
Material
Features
Cable shielding
PUR mixture
Halogen-free
From tinned copper wires
Table 130: RS422 - Cable requirements
3.10.3.10 Contents of delivery
The screws included in the mounting kit are to be used for installation.
2 x
1 x
Figure 75: 5AC600.485I-00 - Contents of the delivery / mounting material
