Technical data • Individual components
Chapter 2
Technical data
Power Panel 500 user's manual V1.40
125
RXD
RXD
TXD
TXD
9
6
4
1
DATA
DATA
Figure 52: RS232/RS422/RS485 interface - Operation 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.
3.5.1.3.7 RS485 - Bus length and cable type
The maximum transfer rate of 115 kbit/s depends on the type of cable being used.
Extension
Transfer rate
1200 m
Typ. 115 kbit/s
Table 94: RS485 - Bus length and transfer rate
The material used for the cable should have all or most of the following properties in order to achieve an optimal
transfer rate.
RS485 cables
Property
Signal lines
Cable cross section
Wire insulation
Conductor resistance
Stranding
Shield
4x 0.25 mm² (24 AWG / 19), tinned copper stranded wire
PE
≤82 Ω/km
Wires stranded in pairs
Paired shield with aluminum foil
Grounding line
Cable cross section
Wire insulation
Conductor cross section
1x 0.34 mm² (22 AWG / 19), tinned copper stranded wire
PE
≤59 Ω/km
Outer sheathing
Material
Features
Complete shielding
PUR mixture
Halogen-free
From tinned copper wires
Table 95: RS485 - Cable requirements
3.5.1.3.8 Terminating resistor
A terminating resistor for the serial interface is already integrated on the I/O board. It can be enabled or disabled
with a switch between the serial interface and the audio interface. An active terminating resistor is indicated by
a yellow LED.
